1
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Wootton JM, Tam JKF, Unsworth WP. Cascade ring expansion reactions for the synthesis of medium-sized rings and macrocycles. Chem Commun (Camb) 2024; 60:4999-5009. [PMID: 38655659 DOI: 10.1039/d4cc01303d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
This Feature Article discusses recent advances in the development of cascade ring expansion reactions for the synthesis of medium-sized rings and macrocycles. Cascade ring expansion reactions have much potential for use in the synthesis of biologically important medium-sized rings and macrocycles, most notably as they don't require high dilution conditions, which are commonly used in established end-to-end macrocyclisation methods. Operation by cascade ring expansion method can allow large ring products to be accessed via rearrangements that proceed exclusively by normal-sized ring cyclisation steps. Ensuring that there is adequate thermodynamic driving force for ring expansion is a key challenge when designing such methods, especially for the expansion of normal-sized rings into medium-sized rings. This Article is predominantly focused on methods developed in our own laboratory, with selected works by other groups also discussed. Thermodynamic considerations, mechanism, reaction design, route planning and future perspective for this field are all covered.
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Affiliation(s)
- Jack M Wootton
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Jerry K F Tam
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
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2
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Barber V, Mielke T, Cartwright J, Díaz-Rodríguez A, Unsworth WP, Grogan G. Unspecific Peroxygenase (UPO) can be Tuned for Oxygenation or Halogenation Activity by Controlling the Reaction pH. Chemistry 2024:e202401706. [PMID: 38700372 DOI: 10.1002/chem.202401706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
Unspecific Peroxygenases (UPOs) are increasingly significant enzymes for selective oxygenations as they are stable, highly active and catalyze their reactions at the expense of only hydrogen peroxide as the oxidant. Their structural similarity to chloroperoxidase (CPO) means that UPOs can also catalyze halogenation reactions based upon the generation of hypohalous acids from halide and H2O2. Here we show that the halogenation and oxygenation modes of a UPO can be stimulated at different pH values. Using simple aromatic compounds such as thymol, we show that, at a pH of 3.0 and 6.0, either brominated or oxygenated products respectively are produced. Preparative 100 mg scale transformations of substrates were performed with 60-72 % isolated yields of brominated products obtained. A one-pot bromination-oxygenation cascade reaction on 4-ethylanisole, in which the pH was adjusted from 3.0 to 6.0 at the halfway stage, yielded sequentially brominated and oxygenated products 1-(3-bromo-4-methoxyphenyl)ethyl alcohol and 3-bromo-4-methoxy acetophenone with 82 % combined conversion. These results identify UPOs as an unusual example of a biocatalyst that is tunable for entirely different chemical reactions, dependent upon the reaction conditions.
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Affiliation(s)
- Verity Barber
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Tamara Mielke
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Jared Cartwright
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK
| | - Alba Díaz-Rodríguez
- GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Gideon Grogan
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
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3
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Yang Z, Arnoux M, Hazelard D, Hughes OR, Nabarro J, Whitwood AC, Fascione MA, Spicer CD, Compain P, Unsworth WP. Expanding the scope of the successive ring expansion strategy for macrocycle and medium-sized ring synthesis: unreactive and reactive lactams. Org Biomol Chem 2024; 22:2985-2991. [PMID: 38526035 DOI: 10.1039/d4ob00285g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
New methods are described that expand the scope of the Successive Ring Expansion (SuRE) with respect to synthetically challenging lactams. A protocol has been developed for use with 'unreactive' lactams, enabling SuRE reactions to be performed on subsrates that fail under previously established conditions. Ring expansion is also demonstarted on 'reactive' lactams derived from iminosugars for the first time. The new SuRE methods were used to prepare a diverse array of medium-sized and macrocyclic lactams and lactones, which were evaluted in an anti-bacterial assay against E. coli BW25113WT.
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Affiliation(s)
- Zhongzhen Yang
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Marion Arnoux
- Laboratoire d'Innovation Moléculaire et Applications (LIMA), Univ. de Strasbourg, Univ. de Haute-Alsace, CNRS (UMR 7042), Equipe de Synthèse Organique et Molécules Bioactives (SYBIO), ECPM, 25 Rue Becquerel, 67000 Strasbourg, France.
| | - Damien Hazelard
- Laboratoire d'Innovation Moléculaire et Applications (LIMA), Univ. de Strasbourg, Univ. de Haute-Alsace, CNRS (UMR 7042), Equipe de Synthèse Organique et Molécules Bioactives (SYBIO), ECPM, 25 Rue Becquerel, 67000 Strasbourg, France.
| | - Owen R Hughes
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
- York Biomedical Research Institute, University of York, Heslington, YO10 5DD, UK
| | - Joe Nabarro
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
- York Biomedical Research Institute, University of York, Heslington, YO10 5DD, UK
| | - Adrian C Whitwood
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Martin A Fascione
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
- York Biomedical Research Institute, University of York, Heslington, YO10 5DD, UK
| | - Christopher D Spicer
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
- York Biomedical Research Institute, University of York, Heslington, YO10 5DD, UK
| | - Philippe Compain
- Laboratoire d'Innovation Moléculaire et Applications (LIMA), Univ. de Strasbourg, Univ. de Haute-Alsace, CNRS (UMR 7042), Equipe de Synthèse Organique et Molécules Bioactives (SYBIO), ECPM, 25 Rue Becquerel, 67000 Strasbourg, France.
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
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4
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Smit SJ, Ayten S, Radzikowska BA, Hamilton JP, Langer S, Unsworth WP, Larson TR, Buell CR, Lichman BR. The genomic and enzymatic basis for iridoid biosynthesis in cat thyme (Teucrium marum). Plant J 2024. [PMID: 38489316 DOI: 10.1111/tpj.16698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/30/2024] [Accepted: 02/14/2024] [Indexed: 03/17/2024]
Abstract
Iridoids are non-canonical monoterpenoids produced by both insects and plants. An example is the cat-attracting and insect-repelling volatile iridoid nepetalactone, produced by Nepeta sp. (catmint) and aphids. Recently, both nepetalactone biosynthetic pathways were elucidated, showing a remarkable convergent evolution. The iridoid, dolichodial, produced by Teucrium marum (cat thyme) and multiple insect species, has highly similar properties to nepetalactone but its biosynthetic origin remains unknown. We set out to determine the genomic, enzymatic, and evolutionary basis of iridoid biosynthesis in T. marum. First, we generated a de novo chromosome-scale genome assembly for T. marum using Oxford Nanopore Technologies long reads and proximity-by-ligation Hi-C reads. The 610.3 Mb assembly spans 15 pseudomolecules with a 32.9 Mb N50 scaffold size. This enabled identification of iridoid biosynthetic genes, whose roles were verified via activity assays. Phylogenomic analysis revealed that the evolutionary history of T. marum iridoid synthase, the iridoid scaffold-forming enzyme, is not orthologous to typical iridoid synthases but is derived from its conserved paralog. We discovered an enzymatic route from nepetalactol to diverse iridoids through the coupled activity of an iridoid oxidase cytochrome P450 and acetyltransferases, via an inferred acylated intermediate. This work provides a genomic resource for specialized metabolite research in mints and demonstration of the role of acetylation in T. marum iridoid diversity. This work will enable future biocatalytic or biosynthetic production of potent insect repellents, as well as comparative studies into iridoid biosynthesis in insects.
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Affiliation(s)
- Samuel J Smit
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Sefa Ayten
- Institute of Plant Breeding, Genetics, & Genomics, University of Georgia, Athens, Georgia, 30602, USA
| | - Barbara A Radzikowska
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - John P Hamilton
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, 30602, USA
- Department of Crop & Soil Sciences, University of Georgia, Athens, Georgia, 30602, USA
| | - Swen Langer
- Bioscience Technology Facility, Department of Biology, University of York, York, YO10 5DD, UK
| | | | - Tony R Larson
- Bioscience Technology Facility, Department of Biology, University of York, York, YO10 5DD, UK
| | - C Robin Buell
- Institute of Plant Breeding, Genetics, & Genomics, University of Georgia, Athens, Georgia, 30602, USA
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, 30602, USA
- Department of Crop & Soil Sciences, University of Georgia, Athens, Georgia, 30602, USA
| | - Benjamin R Lichman
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
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5
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Orukotan WE, Palate KY, Pogrányi B, Bobinski P, Epton RG, Duff L, Whitwood AC, Grogan G, Lynam JM, Unsworth WP. Divergent Cascade Ring-Expansion Reactions of Acryloyl Imides. Chemistry 2024; 30:e202303270. [PMID: 37987097 DOI: 10.1002/chem.202303270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 11/22/2023]
Abstract
Macrocyclic and medium-sized ring ketones, lactones and lactams can all be made from common acryloyl imide starting materials through divergent, one-pot cascade ring-expansion reactions. Following either conjugate addition with an amine or nitromethane, or osmium(VIII)-catalysed dihydoxylation, rearrangement through a four-atom ring expansion takes place spontaneously to form the ring expanded products. A second ring expansion can also be performed following a second iteration of imide formation and alkene functionalisation/ring expansion. In the dihydroxylation series, three- or four-atom ring expansion can be performed selectively, depending on whether the reaction is under kinetic or thermodynamic control.
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Affiliation(s)
- Will E Orukotan
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | | | - Balázs Pogrányi
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Philipp Bobinski
- Organisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Ryan G Epton
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Lee Duff
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | | | - Gideon Grogan
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Jason M Lynam
- Department of Chemistry, University of York, York, YO10 5DD, UK
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6
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Yang Z, Tam JKF, Wootton JM, Lynam JM, Unsworth WP. Ring expansion reactions of PO-containing molecules. Chem Commun (Camb) 2023. [PMID: 37278604 DOI: 10.1039/d3cc02087h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A series of ring expansion reactions of PO-containing molecules have been developed for the synthesis of medium-sized ring cyclic phosphonate esters and phosphonamidates. The reactivity trends initially appear to be counter-intuitive, compared with more well established ring expansion reactions of lactam derivatives, but are explained by considering the differences in heteroatom bonding to P and C respectively.
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Affiliation(s)
- Zhongzhen Yang
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Jerry K F Tam
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Jack M Wootton
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Jason M Lynam
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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7
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Yang Z, Zalessky I, Epton RG, Whitwood AC, Lynam JM, Unsworth WP. Ring Expansion Strategies for the Synthesis of Medium Sized Ring and Macrocyclic Sulfonamides. Angew Chem Int Ed Engl 2023; 62:e202217178. [PMID: 36716014 DOI: 10.1002/anie.202217178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/16/2023] [Accepted: 01/30/2023] [Indexed: 01/31/2023]
Abstract
Two new ring expansion strategies are reported for the synthesis of medium sized ring and macrocyclic sulfonamides. Both methods can be performed without using classical protecting groups, with the key ring expansion step initiated by nitro reduction and amine conjugate addition respectively. Each method can be used to make diversely functionalised cyclic sulfonamides in good to excellent yields, in a range of ring sizes. The ring size dependency of the synthetic reactions is in good agreement with the outcomes modelled by Density Functional Theory calculations.
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Affiliation(s)
- Zhongzhen Yang
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Illya Zalessky
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Ryan G Epton
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | | | - Jason M Lynam
- Department of Chemistry, University of York, York, YO10 5DD, UK
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8
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Pogrányi B, Mielke T, Díaz-Rodríguez A, Cartwright J, Unsworth WP, Grogan G. Preparative-Scale Biocatalytic Oxygenation of N-Heterocycles with a Lyophilized Peroxygenase Catalyst. Angew Chem Int Ed Engl 2023; 62:e202214759. [PMID: 36453718 PMCID: PMC10107140 DOI: 10.1002/anie.202214759] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/17/2022] [Accepted: 11/30/2022] [Indexed: 12/02/2022]
Abstract
A lyophilized preparation of an unspecific peroxygenase variant from Agrocybe aegerita (rAaeUPO-PaDa-I-H) is a highly effective catalyst for the oxygenation of a diverse range of N-heterocyclic compounds. Scalable biocatalytic oxygenations (27 preparative examples, ca. 100 mg scale) have been developed across a wide range of substrates, including alkyl pyridines, bicyclic N-heterocycles and indoles. H2 O2 is the only stoichiometric oxidant needed, without auxiliary electron transport proteins, which is key to the practicality of the method. Reaction outcomes can be altered depending on whether hydrogen peroxide was delivered by syringe pump or through in situ generation using an alcohol oxidase from Pichia pastoris (PpAOX) and methanol as a co-substrate. Good synthetic yields (up to 84 %), regioselectivity and enantioselectivity (up to 99 % ee) were observed in some cases, highlighting the promise of UPOs as practical, versatile and scalable oxygenation biocatalysts.
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Affiliation(s)
- Balázs Pogrányi
- Department of Chemistry, University of York, Heslington York, YO10 5DD, UK
| | - Tamara Mielke
- Department of Chemistry, University of York, Heslington York, YO10 5DD, UK
| | - Alba Díaz-Rodríguez
- GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK
| | - Jared Cartwright
- Department of Biology, University of York, Heslington York, YO10 5DD, UK
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington York, YO10 5DD, UK
| | - Gideon Grogan
- Department of Chemistry, University of York, Heslington York, YO10 5DD, UK
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9
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Robinson WXQ, Mielke T, Melling B, Cuetos A, Parkin A, Unsworth WP, Cartwright J, Grogan G. Comparing the Catalytic and Structural Characteristics of a 'Short' Unspecific Peroxygenase (UPO) Expressed in Pichia pastoris and Escherichia coli. Chembiochem 2023; 24:e202200558. [PMID: 36374006 PMCID: PMC10098773 DOI: 10.1002/cbic.202200558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/14/2022] [Indexed: 11/16/2022]
Abstract
Unspecific peroxygenases (UPOs) have emerged as valuable tools for the oxygenation of non-activated carbon atoms, as they exhibit high turnovers, good stability and depend only on hydrogen peroxide as the external oxidant for activity. However, the isolation of UPOs from their natural fungal sources remains a barrier to wider application. We have cloned the gene encoding an 'artificial' peroxygenase (artUPO), close in sequence to the 'short' UPO from Marasmius rotula (MroUPO), and expressed it in both the yeast Pichia pastoris and E. coli to compare the catalytic and structural characteristics of the enzymes produced in each system. Catalytic efficiency for the UPO substrate 5-nitro-1,3-benzodioxole (NBD) was largely the same for both enzymes, and the structures also revealed few differences apart from the expected glycosylation of the yeast enzyme. However, the glycosylated enzyme displayed greater stability, as determined by nano differential scanning fluorimetry (nano-DSF) measurements. Interestingly, while artUPO hydroxylated ethylbenzene derivatives to give the (R)-alcohols, also given by a variant of the 'long' UPO from Agrocybe aegerita (AaeUPO), it gave the opposite (S)-series of sulfoxide products from a range of sulfide substrates, broadening the scope for application of the enzymes. The structures of artUPO reveal substantial differences to that of AaeUPO, and provide a platform for investigating the distinctive activity of this and related'short' UPOs.
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Affiliation(s)
- Wendy X Q Robinson
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Tamara Mielke
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Benjamin Melling
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Anibal Cuetos
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Alison Parkin
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - William P Unsworth
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Jared Cartwright
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK
| | - Gideon Grogan
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
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10
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Pogrányi B, Mielke TF, Díaz-Rodriguez A, Cartwright J, Unsworth WP, Grogan G. Preparative‐Scale Biocatalytic Oxygenation of N‐Heterocycles with a Lyophilized Peroxygenase Catalyst. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202214759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- Balázs Pogrányi
- University of York Chemistry University of YorkHeslington YO10 5DD York UNITED KINGDOM
| | - Tamara F Mielke
- University of York Chemistry University of YorkHeslington YO10 5DD York UNITED KINGDOM
| | - Alba Díaz-Rodriguez
- GSK: GlaxoSmithKline Plc GSK Medicines Research Centre Gunnel's WoodStevenageHertfordshire SG1 2NY UNITED KINGDOM
| | - Jared Cartwright
- University of York Biology University of YorkHeslington YO10 5DD York UNITED KINGDOM
| | - William P Unsworth
- University of York Chemistry University of YorkHeslington YO10 5DD York UNITED KINGDOM
| | - Gideon Grogan
- University of York Department of Chemistry Chemistry Heslington YO10 5DD York UNITED KINGDOM
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11
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Oddy MJ, Kusza DA, Epton RG, Lynam JM, Unsworth WP, Petersen WF. Visible‐Light Mediated Energy Transfer Enables the Synthesis of β‐Lactams via Intramolecular Hydrogen Atom Transfer. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202213086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Meghan J Oddy
- University of Cape Town Department of Chemistry 7700 Cape Town SOUTH AFRICA
| | - Daniel A Kusza
- University of Cape Town Department of Chemistry Rondebosch 7700 Cape Town SOUTH AFRICA
| | - Ryan G Epton
- University of York Department of Chemistry Heslington YO10 5DD York UNITED KINGDOM
| | - Jason M Lynam
- University of York Department of Chemistry Heslington YO10 5DD York UNITED KINGDOM
| | - William P Unsworth
- University of York Department of Chemistry Heslington YO10 5DD York UNITED KINGDOM
| | - Wade F Petersen
- University of Cape Town Chemistry Upper CampusUniversity of Cape TownRondebosch 7700 Cape Town SOUTH AFRICA
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12
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Inprung N, Ho HE, Rossi-Ashton JA, Epton RG, Whitwood AC, Lynam JM, Taylor RJK, James MJ, Unsworth WP. Indole-ynones as Privileged Substrates for Radical Dearomatizing Spirocyclization Cascades. Org Lett 2022; 24:668-674. [PMID: 34985297 DOI: 10.1021/acs.orglett.1c04098] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Indole-ynones have been established as general substrates for radical dearomatizing spirocyclization cascade reactions. Five distinct and varied synthetic protocols have been developed─cyanomethylation, sulfonylation, trifluoromethylation, stannylation and borylation─using a variety of radical generation modes, ranging from photoredox catalysis to traditional AIBN methods. The simple and easily prepared indole-ynones can be used to rapidly generate diverse, densely functionalized spirocycles and have the potential to become routinely used to explore radical reactivity. Experimental and computational investigations support the proposed radical cascade mechanism and suggest that other new methods are now primed for development.
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Affiliation(s)
- Nantachai Inprung
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Hon Eong Ho
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | | | - Ryan G Epton
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Adrian C Whitwood
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Jason M Lynam
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Richard J K Taylor
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Michael J James
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
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13
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Palate KY, Yang Z, Whitwood AC, Unsworth WP. Synthesis of medium-ring lactams and macrocyclic peptide mimetics via conjugate addition/ring expansion cascade reactions. RSC Chem Biol 2022; 3:334-340. [PMID: 35359493 PMCID: PMC8905531 DOI: 10.1039/d1cb00245g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 02/08/2022] [Indexed: 11/30/2022] Open
Abstract
A novel conjugate addition/ring expansion (CARE) cascade reaction sequence is reported that enables medium-sized ring and macrocyclic bis-lactams to be prepared from primary amines and cyclic imides. The reactions are simple to perform, generally high yielding, and very broad in scope, especially with respect to the primary amine component. CARE reactions can also be performed iteratively, enabling β-peptoid-based macrocyclic peptide mimetics to be ‘grown’ via well controlled, sequential 4-atom ring expansion reactions, with the incorporation of varied functionalised amines during each iteration. A conjugate addition/ring expansion (CARE) cascade reaction sequence is reported that enables medium-sized ring and macrocyclic bis-lactams to be prepared from primary amines and cyclic imides.![]()
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Affiliation(s)
- Kleopas Y Palate
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
| | - Zhongzhen Yang
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
| | - Adrian C Whitwood
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
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14
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Palate KY, Epton RG, Whitwood AC, Lynam JM, Unsworth WP. Synthesis of macrocyclic and medium-sized ring thiolactones via the ring expansion of lactams. Org Biomol Chem 2021; 19:1404-1411. [PMID: 33491715 DOI: 10.1039/d0ob02502j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A side chain insertion method for the ring expansion of lactams into macrocyclic thiolactones is reported, that can also be incorporated into Successive Ring Expansion (SuRE) sequences. The reactions are less thermodynamically favourable than the analogous lactam- and lactone-forming ring expansion processes (with this notion supported by DFT data), but nonetheless, three complementary protecting group strategies have been developed to enable this challenging transformation to be achieved.
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Affiliation(s)
- Kleopas Y Palate
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Ryan G Epton
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Adrian C Whitwood
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Jason M Lynam
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
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15
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Abstract
Medium-sized rings have much promise in medicinal chemistry, but are difficult to make using direct cyclisation methods. In this minireview, we highlight the value of ring expansion strategies to address this long-standing synthetic challenge. We have drawn on recent progress (post 2013) to highlight the key reaction design features that enable successful ‘normal-to-medium’ ring expansion for the synthesis of these medicinally important molecular frameworks, that are currently under-represented in compound screening collections and marketed drugs in view of their challenging syntheses. Ring expansion strategies are ideally suited to make synthetically challenging, medium-sized rings with much potential in medicinal chemistry.![]()
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Affiliation(s)
- Aimee K Clarke
- Department of Chemistry, University of York York YO10 5DD UK
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16
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Abstract
![]()
The polycyclic core of the akuammiline
alkaloids can be synthesized
from simple tryptamine and tryptophol derivatives via a Ag(I)-catalyzed
enantioselective dearomative cyclization cascade sequence. The complex
tetracyclic scaffolds are prepared via a rapid, versatile, three-step
modular synthesis from simple commercially available indole derivatives
in high yields and enantiomeric excess (up to 99% yield and >99% ee).
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Affiliation(s)
| | - Aimee K Clarke
- Department of Chemistry , University of York , York , YO10 5DD , U.K
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17
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Ho HE, Pagano A, Rossi-Ashton JA, Donald JR, Epton RG, Churchill JC, James MJ, O'Brien P, Taylor RJK, Unsworth WP. Visible-light-induced intramolecular charge transfer in the radical spirocyclisation of indole-tethered ynones. Chem Sci 2019; 11:1353-1360. [PMID: 34123259 PMCID: PMC8148050 DOI: 10.1039/c9sc05311e] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Indole-tethered ynones form an intramolecular electron donor–acceptor complex that can undergo visible-light-induced charge transfer to promote thiyl radical generation from thiols. This initiates a novel radical chain sequence, based on dearomatising spirocyclisation with concomitant C–S bond formation. Sulfur-containing spirocycles are formed in high yields using this simple and mild synthetic protocol, in which neither transition metal catalysts nor photocatalysts are required. The proposed mechanism is supported by various mechanistic studies, and the unusual radical initiation mode represents only the second report of the use of an intramolecular electron donor–acceptor complex in synthesis. Indole-tethered ynones form an intramolecular electron donor–acceptor complex that can undergo visible-light-induced charge transfer to promote thiyl radical generation from thiols.![]()
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Affiliation(s)
- Hon Eong Ho
- Department of Chemistry, University of York York YO10 5DD UK
| | - Angela Pagano
- Department of Chemistry and Industrial Chemistry, University of Genova via Dodecaneso, 31 16146 Genova Italy
| | | | - James R Donald
- Department of Chemistry, University of York York YO10 5DD UK
| | - Ryan G Epton
- Department of Chemistry, University of York York YO10 5DD UK
| | | | - Michael J James
- Department of Chemistry, University of York York YO10 5DD UK
| | - Peter O'Brien
- Department of Chemistry, University of York York YO10 5DD UK
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18
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Gkotsi DS, Ludewig H, Sharma SV, Connolly JA, Dhaliwal J, Wang Y, Unsworth WP, Taylor RJK, McLachlan MMW, Shanahan S, Naismith JH, Goss RJM. A marine viral halogenase that iodinates diverse substrates. Nat Chem 2019; 11:1091-1097. [PMID: 31611633 PMCID: PMC6875430 DOI: 10.1038/s41557-019-0349-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 09/09/2019] [Indexed: 11/23/2022]
Abstract
Oceanic cyanobacteria are the most abundant oxygen-generating phototrophs on our planet, and therefore, important to life. These organisms are infected by viruses called cyanophages, recently shown to encode metabolic genes that modulate host photosynthesis, phosphorus cycling and nucleotide metabolism. Herein, we report the characterisation of a wild type flavin-dependent viral halogenase (VirX1) from a cyanophage. Notably, halogenases have been previously associated with secondary metabolism, tailoring natural products. Exploration of this viral halogenase reveals it capable of regioselective halogenation of a diverse range of substrates, with a preference for forming aryl iodide species; this has potential implications for the metabolism of the infected host. Until recently, a flavin-dependent halogenase (FDH) capable of iodination in vitro had not been reported. VirX1 is interesting from a biocatalytic perspective showing strikingly broad substrate flexibility, and a clear preference for iodination, as illustrated by kinetic analysis. These factors together render it an attractive tool for synthesis.
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Affiliation(s)
- Danai S Gkotsi
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Hannes Ludewig
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Sunil V Sharma
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Jack A Connolly
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Jagwinder Dhaliwal
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | - Yunpeng Wang
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK
| | | | | | - Matthew M W McLachlan
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, UK.,QEDDI, The University of Queensland, Brisbane, Queensland, Australia
| | - Stephen Shanahan
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, UK
| | - James H Naismith
- Division of Structural Biology, Wellcome Trust Centre of Human Genomics, Oxford, UK.,Research Complex at Harwell, Rutherford Laboratory, Didcot, UK.,The Rosalind Franklin Institute, Didcot, UK
| | - Rebecca J M Goss
- School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK. .,Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, UK.
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19
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Liddon JTR, Rossi-Ashton JA, Taylor RJK, Unsworth WP. Dearomatizing Spiroannulation Reagents: Direct Access to Spirocycles from Indoles and Dihalides. Org Lett 2018; 20:3349-3353. [PMID: 29745671 DOI: 10.1021/acs.orglett.8b01248] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Unfunctionalized indoles can be directly converted into 3,3'-spirocyclic indolenines and indolines upon reaction with electrophilic dihalides in the presence of t-BuOK/BEt3. This double C-C bond forming reaction, which simultaneously generates a quaternary spirocyclic center, typically proceeds in high yield and has good functional group tolerance. In contrast to existing dearomatizing spirocyclization approaches, there is no need to prepare a prefunctionalized aromatic precursor, enabling faster access to valuable spirocyclic products from simple, commercially available aromatics in one step.
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Affiliation(s)
- John T R Liddon
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
| | | | - Richard J K Taylor
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
| | - William P Unsworth
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
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20
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Stephens TC, Lodi M, Steer AM, Lin Y, Gill MT, Unsworth WP. Synthesis of Cyclic Peptide Mimetics by the Successive Ring Expansion of Lactams. Chemistry 2017; 23:13314-13318. [PMID: 28722215 DOI: 10.1002/chem.201703316] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Indexed: 12/12/2022]
Abstract
A successive ring-expansion protocol is reported that enables the controlled insertion of natural and non-natural amino acid fragments into lactams. Amino acids can be installed into macrocycles via an operationally simple and scalable iterative procedure, without the need for high dilution. This method is expected to be of broad utility, especially for the synthesis of medicinally important cyclic peptide mimetics.
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Affiliation(s)
| | - Mahendar Lodi
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Andrew M Steer
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Yun Lin
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Matthew T Gill
- Department of Chemistry, University of York, York, YO10 5DD, UK
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21
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Baud LG, Manning MA, Arkless HL, Stephens TC, Unsworth WP. Ring-Expansion Approach to Medium-Sized Lactams and Analysis of Their Medicinal Lead-Like Properties. Chemistry 2017; 23:2225-2230. [PMID: 27935197 DOI: 10.1002/chem.201605615] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 12/20/2022]
Abstract
Medium-sized rings are widely considered to be under-represented in biological screening libraries for lead identification in medicinal chemistry. To help address this, a library of medium-sized lactams has been generated by using a simple, scalable and versatile ring-expansion protocol. Analysis of the library by using open-access computational tool LLAMA suggested that these lactams and their derivatives have highly promising physicochemical and 3D spatial properties and thus have much potential in drug discovery.
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22
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Lloyd MG, D'Acunto M, Taylor RJK, Unsworth WP. A selective C-H insertion/olefination protocol for the synthesis of α-methylene-γ-butyrolactone natural products. Org Biomol Chem 2016; 14:1641-5. [PMID: 26695888 DOI: 10.1039/c5ob02579f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A regio- and stereoselective one-pot C-H insertion/olefination protocol has been developed for the late stage installation of α-methylene-γ-butyrolactones into conformationally restricted cyclohexanol-derivatives. The method has been successfully applied in the total synthesis of eudesmanolide natural product frameworks, including α-cyclocostunolide.
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Affiliation(s)
- Matthew G Lloyd
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Mariantonietta D'Acunto
- University of Salerno, Department of Chemistry and Biology, Via Giovanni Paolo II, 132, Salerno, 84084 Fisciano, Italy
| | - Richard J K Taylor
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
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23
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Liddon JTR, James MJ, Clarke AK, O'Brien P, Taylor RJK, Unsworth WP. Catalyst-Driven Scaffold Diversity: Selective Synthesis of Spirocycles, Carbazoles and Quinolines from Indolyl Ynones. Chemistry 2016; 22:8777-80. [PMID: 27124236 PMCID: PMC5084754 DOI: 10.1002/chem.201601836] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 12/13/2022]
Abstract
Medicinally relevant spirocyclic indolenines, carbazoles and quinolines can each be directly synthesised selectively from common indolyl ynone starting materials by catalyst variation. The high yielding, divergent reactions all proceed by an initial dearomatising spirocyclisation reaction to generate an intermediate vinyl-metal species, which then rearranges selectively by careful choice of catalyst and reaction conditions.
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24
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Chambers SJ, Coulthard G, Unsworth WP, O'Brien P, Taylor RJK. From Heteroaromatic Acids and Imines to Azaspirocycles: Stereoselective Synthesis and 3D Shape Analysis. Chemistry 2016; 22:6496-500. [PMID: 26918778 PMCID: PMC5071705 DOI: 10.1002/chem.201600823] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Indexed: 12/19/2022]
Abstract
Heteroaromatic carboxylic acids have been directly coupled with imines using propylphosphonic anhydride (T3P) and NEt(iPr)2 to form azaspirocycles via intermediate N-acyliminium ions. Spirocyclic indolenines (3H-indoles), azaindolenines, 2H-pyrroles and 3H-pyrroles were all accessed using this metal-free approach. The reactions typically proceed with high diastereoselectivity and 3D shape analysis confirms that the products formed occupy areas of chemical space that are under-represented in existing drugs and high throughput screening libraries.
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Affiliation(s)
| | | | | | - Peter O'Brien
- Department of Chemistry, University of York, York, UK
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25
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Kitsiou C, Hindes JJ, I'Anson P, Jackson P, Wilson TC, Daly EK, Felstead HR, Hearnshaw P, Unsworth WP. The Synthesis of Structurally Diverse Macrocycles By Successive Ring Expansion. Angew Chem Int Ed Engl 2015; 54:15794-8. [PMID: 26768697 DOI: 10.1002/anie.201509153] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 10/28/2015] [Indexed: 11/10/2022]
Abstract
Structurally diverse macrocycles and medium-sized rings (9-24 membered scaffolds, 22 examples) can be generated through a telescoped acylation/ring-expansion sequence, leading to the insertion of linear fragments into cyclic β-ketoesters without performing a discrete macrocyclization step. The key β-ketoester motif is regenerated in the ring-expanded product, meaning that the same sequence of steps can then be repeated (in theory indefinitely) with other linear fragments, allowing macrocycles with precise substitution patterns to be "grown" from smaller rings using the successive ring-expansion (SuRE) method.
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26
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James MJ, Clubley RE, Palate KY, Procter TJ, Wyton AC, O’Brien P, Taylor RJK, Unsworth WP. Silver(I)-Catalyzed Dearomatization of Alkyne-Tethered Indoles: Divergent Synthesis of Spirocyclic Indolenines and Carbazoles. Org Lett 2015; 17:4372-5. [DOI: 10.1021/acs.orglett.5b02216] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael J. James
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Rosa E. Clubley
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Kleopas Y. Palate
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Thomas J. Procter
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Anthony C. Wyton
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Peter O’Brien
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
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27
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Unsworth WP, Coulthard G, Kitsiou C, Taylor RJK. Direct imine acylation for molecular diversity in heterocyclic synthesis. J Org Chem 2014; 79:1368-76. [PMID: 24437593 DOI: 10.1021/jo402768r] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Imines and carboxylic acids have been directly coupled using propylphosphonic acid anhydride and NEt(i-Pr)2 to give N-acyliminium ions, which were intramolecularly trapped with oxygen, nitrogen, sulfur, and carbon nucleophiles to provide a wide range of structurally diverse heterocycles.
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28
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Abstract
A one-pot C-H insertion/olefination sequence for the conversion of α-diazo-α-(dialkoxyphosphoryl)acetates into α-alkylidene-γ-butyrolactones is reported. The key C-H insertion process is achieved using a catalytic amount of a dirhodium carboxylate catalyst, using operationally simple conditions. The size and electronic properties of the attached substituents were found to influence the regio- and diastereoselectivity of the process. The utility of the process is demonstrated by the synthesis of a known Staphylococcus aureus (MRSA) virulence inhibitor.
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Affiliation(s)
- Matthew G Lloyd
- Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K
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29
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Unsworth WP, Gallagher KA, Jean M, Schmidt JP, Diorazio LJ, Taylor RJK. Direct imine acylation: synthesis of the proposed structures of 'upenamide. Org Lett 2012; 15:262-5. [PMID: 23265326 DOI: 10.1021/ol3030764] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of the two proposed structures of macrocyclic marine natural product 'upenamide is reported. The key step utilizes direct imine acylation (DIA) with a protected β-hydroxy acid to construct the key tricyclic ABC ring system. The macrocyclization was completed in the final step using a Stille cross-coupling reaction.
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Affiliation(s)
- William P Unsworth
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
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30
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Sanger GJ, Westaway SM, Barnes AA, Macpherson DT, Muir AI, Jarvie EM, Bolton VN, Cellek S, Näslund E, Hellström PM, Borman RA, Unsworth WP, Matthews KL, Lee K. GSK962040: a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility. Neurogastroenterol Motil 2009; 21:657-64, e30-1. [PMID: 19374732 DOI: 10.1111/j.1365-2982.2008.01270.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
There is an urgent clinical need for a safe, efficacious stimulant of gastric emptying; current therapies include erythromycin (an antibiotic with additional properties which preclude chronic use) and metoclopramide (a 5-hydroxytryptamine type 4 receptor agonist and an antagonist at brain D2 receptors, associated with movement disorders). To move away from the complex motilide structure of erythromycin, a small molecule motilin receptor agonist, GSK962040, was identified and characterized. The compound was evaluated using recombinant human receptors, rabbit and human isolated stomach preparations known to respond to motilin and in vivo, by measuring its ability to increase defecation in conscious rabbits. At the human motilin receptor, the pEC50 (the negative logarithm to base 10 of the EC50 value, the concentration of agonist that produces 50% of the maximal response) values for GSK962040 and erythromycin as agonists were, respectively, 7.9 and 7.3; GSK962040 had no significant activity at a range of other receptors (including ghrelin), ion channels and enzymes. In rabbit gastric antrum, GSK962040 300 nmol L(-1)-10 micromol L(-1) caused a prolonged facilitation of the amplitude of cholinergically mediated contractions, to a maximum of 248 +/- 47% at 3 micromol L(-1). In human-isolated stomach, GSK962040 10 micromol L(-1), erythromycin 10 micromol L(-1) and [Nle13]-motilin 100 nmol L(-1), each caused muscle contraction of similar amplitude. In conscious rabbits, intravenous doses of 5 mg kg(-1) GSK962040 or 10 mg kg(-1) erythromycin significantly increased faecal output over a 2-h period. Together, these data show that GSK962040, a non-motilide structure, selectively activates the motilin receptor. Simplification of the structural requirements to activate this receptor greatly facilitates the design of potentially new medicines for gastroparesis.
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Affiliation(s)
- G J Sanger
- Immuno-Inflammation CEDD, GlaxoSmithKline, Stevenage, UK.
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31
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Unsworth WP, Taylor JA, Robinson JE. Prenatal programming of reproductive neuroendocrine function: the effect of prenatal androgens on the development of estrogen positive feedback and ovarian cycles in the ewe. Biol Reprod 2004; 72:619-27. [PMID: 15509728 DOI: 10.1095/biolreprod.104.035691] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Exposure of the female ovine fetus to male hormones during a sensitive window of in utero life causes disruption to reproductive function. In some animals, androgen exposure completely abolishes reproductive cycles, but in others, cycles are progressively lost with age. The present study tested two predictions: that noncycling, androgenized animals are unable to respond to estrogen with a preovulatory-like surge of LH (estrogen positive feedback), and that the androgenized animals that exhibit a progressive loss of cycles also show a progressive loss of estrogen positive feedback. Androgenized ewes were generated by injection of their mothers with testosterone propionate twice per week from Day 30 to Day 90 of pregnancy (term, 147 days). Control ewes received no injections. Whether ewes could exhibit estrogen positive feedback was tested on five occasions before puberty (30 wk) and once during the anestrous period. All control animals had repeated reproductive cycles in both the first and second breeding season, and all showed robust LH surges during test periods. Despite the fact that 64% of androgenized animals showed reproductive cycles, estrogen positive feedback could be demonstrated in only 6.1% of trials. Subsequent experiments revealed that the lack of response to estrogen in androgenized animals was not because of pituitary insensitivity to GnRH, a requirement for higher concentrations of estrogen, or a surge that was delayed relative to the time of estrogen administration. The mechanisms by which some androgenized ewes can produce normal reproductive cycles in the apparent absence of estrogen positive feedback are currently unknown.
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Affiliation(s)
- William P Unsworth
- Laboratory of Neuroendocrinology, Department of Neurobiology, The Babraham Institute, Cambridge CB2 4AT, United Kingdom
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32
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Birch RA, Padmanabhan V, Foster DL, Unsworth WP, Robinson JE. Prenatal programming of reproductive neuroendocrine function: fetal androgen exposure produces progressive disruption of reproductive cycles in sheep. Endocrinology 2003; 144:1426-34. [PMID: 12639926 DOI: 10.1210/en.2002-220965] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In the agonadal, androgenized ewe testosterone before birth produces a precocious pubertal rise in circulating LH and abolishes the LH surge mechanism. The present study tested two predictions from this model in the ovary-intact female: 1) prenatal androgen exposure produces early ovarian stimulation; and 2) despite early ovarian stimulation, progestogenic cycles would not occur because of the abolition or disruption of the LH surge. Pregnant ewes were injected with testosterone propionate twice per week from either d 30-90 (T60 group; 100 mg/injection) or d 60-90 (T30 group; 80 mg/injection) of gestation (term, 147 d). Control ewes received no injections. At birth, the androgenized and control lambs were divided into two groups: ovary-intact to determine the effects of prenatal androgen on the timing of puberty and subsequent ovarian function, and ovariectomized to assess the timing of the pubertal decrease in sensitivity to estrogen negative feedback and the subsequent increase in LH. Neonatally orchidectomized, estrogen-treated males were included for comparison of the timing of this pubertal rise in LH secretion. Neuroendocrine puberty (determined on the basis of LH increase) was advanced in the androgenized females to a similar age as in males. Repeated progesterone cycles of the same duration and number occurred in the ovary-intact ewes, and they began at the same time as for control females, thus negating both predictions. Differences appeared during the second breeding season, when reproductive cycles were either absent (T60) or disrupted (T30 group). Our findings reveal that exposure to androgens in utero causes a progressive loss of cyclic function in adulthood.
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Affiliation(s)
- Rachel A Birch
- Laboratory of Neuroendocrinology, Department of Neurobiology, The Babraham Institute, Cambridge CB2 4AT, United Kingdom
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33
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Robinson JE, Birch RA, Grindrod JAE, Taylor JA, Unsworth WP. Sexually differentiated regulation of gnRH release by gonadal steroid hormones in sheep. Reprod Suppl 2003; 61:299-310. [PMID: 14635943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Exposure of the sheep fetus to testosterone from day 30 to day 90 of a 147 day gestation causes the neurones that control GnRH secretion, the GnRH neuronal network, to become organized in a sex-specific manner. After androgen exposure in utero, GnRH neurones are activated in a sexually differentiated pattern by gonadal steroid hormones. Specifically, follicular phase concentrations of oestrogen trigger a GnRH 'surge' in ewes, but not in rams or females treated with androgen during fetal life. Furthermore, progesterone is a less potent inhibitor of GnRH release in rams or females treated with androgen during fetal life. The reasons for the sexual differentiation of these steroid feedback mechanisms probably reside in a dimorphism in steroid-sensitive neural inputs to GnRH neurones. The density of neurones containing oestrogen receptor alpha is sexually differentiated in areas of the ovine brain that are known to be involved in the steroidal regulation of GnRH. Furthermore, neurones in these regions are activated in a gender-specific pattern. A determination of the neural phenotype of these steroid-sensitive cells will form a basis for understanding the mechanisms by which the GnRH neuronal network is organized and activated in a sexually differentiated manner.
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Affiliation(s)
- J E Robinson
- Laboratory of Neuroendocrinology, The Babraham Institute, Babraham, Cambridge CB2 4A7, UK.
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