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Wong JYF, Thomson CG, Vilela F, Barker G. Flash chemistry enables high productivity metalation-substitution of 5-alkyltetrazoles. Chem Sci 2021; 12:13413-13424. [PMID: 34777760 PMCID: PMC8528014 DOI: 10.1039/d1sc04176b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022] Open
Abstract
Tetrazoles play a prominent role in medicinal chemistry due to their role as carboxylate bioisosteres but have largely been overlooked as C-H functionalisation substrates. We herein report the development of a high-yielding and general procedure for the heterobenzylic C-H functionalisation of 5-alkyltetrazoles in up to 97% yield under batch conditions using a metalation/electrophilic trapping strategy. Through the use of thermal imaging to identify potentially unsafe exotherms, a continuous flow procedure using a flash chemistry strategy has also been developed, allowing products to be accessed in up to 95% yield. This enabled an extremely high productivity rate of 141 g h-1 to be achieved on an entry-level flow system.
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Affiliation(s)
- Jeff Y F Wong
- Institute of Chemical Sciences, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
| | - Christopher G Thomson
- Institute of Chemical Sciences, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
| | - Filipe Vilela
- Institute of Chemical Sciences, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
- Continuum Flow Lab, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
| | - Graeme Barker
- Institute of Chemical Sciences, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
- Continuum Flow Lab, Heriot-Watt University Riccarton Edinburgh EH14 4AS UK
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2
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Inoue K, Feng Y, Mori A, Okano K. "Snapshot" Trapping of Multiple Transient Azolyllithiums in Batch. Chemistry 2021; 27:10267-10273. [PMID: 33960030 DOI: 10.1002/chem.202101256] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Indexed: 12/23/2022]
Abstract
Recent developments in flow microreactor technology have allowed the use of transient organolithium compounds that cannot be realized in a batch reactor. However, trapping the transient aryllithiums in a "halogen dance" is still challenging. Herein is reported the trapping of such short-lived azolyllithiums in a batch reactor by developing a finely tuned in situ zincation using zinc halide diamine complexes. The reaction rate is controlled by the appropriate choice of diamine ligand. The reaction is operationally simple and can be performed at 0 °C with high reproducibility on a multigram scale. This method was applicable to a wide range of brominated azoles allowing deprotonative functionalization, which was used for the concise divergent syntheses of both constitutional isomers of biologically active azoles.
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Affiliation(s)
- Kengo Inoue
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Yuxuan Feng
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Atsunori Mori
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan.,Research Center for Membrane and Film Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Kentaro Okano
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
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3
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Jiao J, Nie W, Yu T, Yang F, Zhang Q, Aihemaiti F, Yang T, Liu X, Wang J, Li P. Multi-Step Continuous-Flow Organic Synthesis: Opportunities and Challenges. Chemistry 2021; 27:4817-4838. [PMID: 33034923 DOI: 10.1002/chem.202004477] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Indexed: 12/11/2022]
Abstract
Continuous-flow multi-step synthesis takes the advantages of microchannel flow chemistry and may transform the conventional multi-step organic synthesis by using integrated synthetic systems. To realize the goal, however, innovative chemical methods and techniques are urgently required to meet the significant remaining challenges. In the past few years, by using green reactions, telescoped chemical design, and/or novel in-line separation techniques, major and rapid advancement has been made in this direction. This minireview summarizes the most recent reports (2017-2020) on continuous-flow synthesis of functional molecules. Notably, several complex active pharmaceutical ingredients (APIs) have been prepared by the continuous-flow approach. Key technologies to the successes and remaining challenges are discussed. These results exemplified the feasibility of using modern continuous-flow chemistry for complex synthetic targets, and bode well for the future development of integrated, automated artificial synthetic systems.
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Affiliation(s)
- Jiao Jiao
- School of Chemistry, Xi'an Jiaotong University, Xi'an, 710061, P. R. China.,Xian Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Wenzheng Nie
- School of Chemistry, Xi'an Jiaotong University, Xi'an, 710061, P. R. China.,Xian Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Tao Yu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Fan Yang
- Department of Applied Chemistry, Xi'an University of Technology, Xi'an, 710048, P. R. China
| | - Qian Zhang
- Department of Applied Chemistry, Xi'an University of Technology, Xi'an, 710048, P. R. China
| | - Feierdaiweisi Aihemaiti
- School of Chemistry, Xi'an Jiaotong University, Xi'an, 710061, P. R. China.,Xian Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Tingjun Yang
- School of Chemistry, Xi'an Jiaotong University, Xi'an, 710061, P. R. China.,Xian Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Xuanyu Liu
- School of Medicine, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Jiachen Wang
- School of Medicine, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Pengfei Li
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.,Xian Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
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4
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5
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Dallinger D, Gutmann B, Kappe CO. The Concept of Chemical Generators: On-Site On-Demand Production of Hazardous Reagents in Continuous Flow. Acc Chem Res 2020; 53:1330-1341. [PMID: 32543830 PMCID: PMC7467564 DOI: 10.1021/acs.accounts.0c00199] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
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In recent years, a steadily growing number of chemists, from both
academia and industry, have dedicated their research to the development
of continuous flow processes performed in milli- or microreactors.
The common availability of continuous flow equipment at virtually
all scales and affordable cost has additionally impacted this trend.
Furthermore, regulatory agencies such as the United States Food and
Drug Administration actively encourage continuous manufacturing of
active pharmaceutical ingredients (APIs) with the vision of quality
and productivity improvements. That is why the pharmaceutical industry
is progressively implementing continuous flow technologies. As a result
of the exceptional characteristics of continuous flow reactors such
as small reactor volumes and remarkably fast heat and mass transfer,
process conditions which need to be avoided in conventional batch
syntheses can be safely employed. Thus, continuous operation is particularly
advantageous for reactions at high temperatures/pressures (novel process
windows) and for ultrafast, exothermic reactions (flash chemistry). In addition to conditions that are outside of the operation range
of conventional stirred tank reactors, reagents possessing a high
hazard potential and therefore not amenable to batch processing can
be safely utilized (forbidden chemistry). Because of the small reactor
volumes, risks in case of a failure are minimized. Such hazardous
reagents often are low molecular weight compounds, leading generally
to the most atom-, time-, and cost-efficient route toward the desired
product. Ideally, they are generated from benign, readily available
and cheap precursors within the closed environment of the flow reactor
on-site on-demand. By doing so, the transport, storage, and handling
of those compounds, which impose a certain safety risk especially
on a large scale, are circumvented. This strategy also positively
impacts the global supply chain dependency, which can be a severe
issue, particularly in times of stricter safety regulations or an
epidemic. The concept of the in situ production of a hazardous material
is generally referred to as the “generator” of the material.
Importantly, in an integrated flow process, multiple modules can be
assembled consecutively, allowing not only an in-line purification/separation
and quenching of the reagent, but also its downstream conversion to
a nonhazardous product. For the past decade, research in our
group has focused on the continuous
generation of hazardous reagents using a range of reactor designs
and experimental techniques, particularly toward the synthesis of
APIs. In this Account, we therefore introduce chemical generator concepts
that have been developed in our laboratories for the production of
toxic, explosive, and short-lived reagents. We have defined three
different classes of generators depending on the reactivity/stability
of the reagents, featuring reagents such as Br2, HCN, peracids,
diazomethane (CH2N2), or hydrazoic acid (HN3). The various reactor designs, including in-line membrane
separation techniques and real-time process analytical technologies
for the generation, purification, and monitoring of those hazardous
reagents, and also their downstream transformations are presented.
This Account should serve as food for thought to extend the scope
of chemical generators for accomplishing more efficient and more economic
processes.
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Affiliation(s)
- Doris Dallinger
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
| | - Bernhard Gutmann
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
| | - C. Oliver Kappe
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
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7
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Armstrong RJ, Akhtar WM, Frost JR, Christensen KE, Stevenson NG, Donohoe TJ. Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach. Tetrahedron 2019. [DOI: 10.1016/j.tet.2019.130680] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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8
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Wong JYF, Tobin JM, Vilela F, Barker G. Batch Versus Flow Lithiation–Substitution of 1,3,4‐Oxadiazoles: Exploitation of Unstable Intermediates Using Flow Chemistry. Chemistry 2019; 25:12439-12445. [DOI: 10.1002/chem.201902917] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/26/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Jeff Y. F. Wong
- Institute of Chemical SciencesHeriot-Watt University Riccarton Edinburgh UK
| | - John M. Tobin
- Institute of Chemical SciencesHeriot-Watt University Riccarton Edinburgh UK
| | - Filipe Vilela
- Institute of Chemical SciencesHeriot-Watt University Riccarton Edinburgh UK
| | - Graeme Barker
- Institute of Chemical SciencesHeriot-Watt University Riccarton Edinburgh UK
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9
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Haas CP, Tallarek U. Kinetics Studies on a Multicomponent Knoevenagel-Michael Domino Reaction by an Automated Flow Reactor. ChemistryOpen 2019; 8:606-614. [PMID: 31110932 PMCID: PMC6511915 DOI: 10.1002/open.201900124] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Indexed: 12/13/2022] Open
Abstract
The optimization of complex chemical reaction systems is often a troublesome and time‐consuming process. The application of modern technologies, including automated reactors and analytics, opens the avenue for generating large data sets on chemical reaction processes in a short period of time. In this work, an automated flow reactor is used to present detailed kinetics and mechanistic studies about an amine‐catalyzed Knoevenagel−Michael domino reaction to yield tetrahydrochromene derivatives. High‐performance monoliths as catalyst supports and online coupled HPLC analysis allow for time‐efficient data generation. We show that the two‐step multicomponent domino reaction does not follow the kinetics of consecutive reaction steps proceeding independently from each other. Instead, the starting materials of both individual reactions compete for the active sites on the heterogeneous catalyst, which lowers the rate constants of both steps. This knowledge was used to implement a more efficient experimental setup which increased the turnover numbers of the catalyst, without adjusting common reaction parameters like temperature, reaction time, and concentrations.
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Affiliation(s)
- Christian P Haas
- Department of Chemistry Philipps-Universität Marburg Hans-Meerwein-Strasse 4 D-35032 Marburg Germany
| | - Ulrich Tallarek
- Department of Chemistry Philipps-Universität Marburg Hans-Meerwein-Strasse 4 D-35032 Marburg Germany
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10
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Sagmeister P, Williams JD, Hone CA, Kappe CO. Laboratory of the future: a modular flow platform with multiple integrated PAT tools for multistep reactions. REACT CHEM ENG 2019. [DOI: 10.1039/c9re00087a] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The coupling of a modular microreactor platform, real-time inline analysis by IR and NMR, and online UPLC, leads to efficient optimization of a multistep organolithium transformation to a given product without the need for human intervention.
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Affiliation(s)
- Peter Sagmeister
- Center for Continuous Synthesis and Processing (CCFLOW)
- Research Center Pharmaceutical Engineering (RCPE)
- 8010 Graz
- Austria
- Institute of Chemistry
| | - Jason D. Williams
- Center for Continuous Synthesis and Processing (CCFLOW)
- Research Center Pharmaceutical Engineering (RCPE)
- 8010 Graz
- Austria
- Institute of Chemistry
| | - Christopher A. Hone
- Center for Continuous Synthesis and Processing (CCFLOW)
- Research Center Pharmaceutical Engineering (RCPE)
- 8010 Graz
- Austria
- Institute of Chemistry
| | - C. Oliver Kappe
- Center for Continuous Synthesis and Processing (CCFLOW)
- Research Center Pharmaceutical Engineering (RCPE)
- 8010 Graz
- Austria
- Institute of Chemistry
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11
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Ganiek MA, Ivanova MV, Martin B, Knochel P. Mild Homologation of Esters through Continuous Flow Chloroacetate Claisen Reactions. Angew Chem Int Ed Engl 2018; 57:17249-17253. [PMID: 30290045 DOI: 10.1002/anie.201810158] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/25/2018] [Indexed: 12/11/2022]
Abstract
The selective chloromethylenation of functionalized esters using chloroacetic acid (CA) and LiHMDS (HMDS=hexamethyldisilazide) in a continuous-flow setup is reported. This Claisen homologation is for the first time extended to bis-chloromethylenation using dichloroacetic acid (DCA), thus giving access to under-explored α,α'-bis-chloroketones. The use of flow conditions enables efficient generation and reaction of the unstable chloroacetate dianion intermediates, leading to unprecedented mild and scalable reaction conditions at an economical reagent stoichiometry (-10 °C, <1 min, 1.0-2.4 equiv dianion). The clean reaction profiles allow subsequent use of the unpurified crude products, which is demonstrated in the synthesis of various heterocycles of broad interest. Furthermore, we report a novel, catalyst-free substitution of the obtained monochloro ketone products with (hetero)aryl zinc enolates to give valuable 1,4-diketones.
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Affiliation(s)
- Maximilian A Ganiek
- Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Maria V Ivanova
- Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Benjamin Martin
- Novartis Pharma AG, Chemical Development, Fabrikstrasse, 4002, Basel, Switzerland
| | - Paul Knochel
- Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
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12
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Ganiek MA, Ivanova MV, Martin B, Knochel P. Milde Chlorhomologisierung von Estern durch Chloracetat‐Claisen‐Reaktion unter kontinuierlichen Durchflussbedingungen. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201810158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Maximilian A. Ganiek
- Ludwig-Maximilians-Universität München Department Chemie Butenandtstraße 5–13, Haus F 81377 München Deutschland
| | - Maria V. Ivanova
- Ludwig-Maximilians-Universität München Department Chemie Butenandtstraße 5–13, Haus F 81377 München Deutschland
| | - Benjamin Martin
- Novartis Pharma AG Chemical Development Fabrikstraße 4002 Basel Schweiz
| | - Paul Knochel
- Ludwig-Maximilians-Universität München Department Chemie Butenandtstraße 5–13, Haus F 81377 München Deutschland
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