1
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Liang H, Morken JP. Direct Observation of Alkyl Group Transmetalation from Boron to Copper: Impact of Structure Modification and the Critical Role of Copper-Oxygen Preassociation in Stereospecificity. J Am Chem Soc 2025; 147:13126-13130. [PMID: 40202428 DOI: 10.1021/jacs.5c03197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2025]
Abstract
Mechanistic investigations of prospective intermediates in copper-catalyzed cross-coupling reactions with alkyllithium-activated alkylboronic esters are described. Complexes between (NHC)copper and the borate salts were characterized by X-ray crystallography and NMR, and the rate of intramolecular transmetalation of an alkyl group from boron to copper was measured. Derived activation parameters were correlated with those determined by DFT analysis and give insight into the mechanism of stereospecific transmetalation.
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Affiliation(s)
- Hao Liang
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - James P Morken
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
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2
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Zheng W, Cao Y, Tan BB, Wang Y, Ge S, Lu Y. Ligand-Controlled Enantioselective Copper-Catalyzed Hydroboration and Ring-Opening Dihydroboration of Arylidenecyclobutanes. J Am Chem Soc 2025; 147:12273-12284. [PMID: 40131741 DOI: 10.1021/jacs.5c01729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2025]
Abstract
Arylidenecyclobutanes are readily accessible and versatile reagents in synthetic chemistry due to the multifaceted reactivity exhibited by their alkene and strained cyclobutane moieties. However, metal-catalyzed enantioselective functionalization of arylidenecyclobutanes, particularly the controllable ring-retaining and ring-opening reactions, is rarely explored. Considering the versatile synthetic utility of enantioenriched organoboronate compounds, herein we report ligand-controlled enantioselective copper-catalyzed ring-retaining hydroboration and ring-opening dihydroboration reactions of arylidenecyclobutanes that afford chiral α-cyclobutyl benzylboronate and 1,5-diboronate compounds with high enantioselectivity when (S)-DTBM-Segphos and (S,S)-Ph-BPE are employed, respectively. Mechanistic studies reveal that the ring-opening process of arylidenecyclobutanes via β-C elimination is significantly slower than that of arylidenecyclopropanes in the presence of CuOAc and (S,S)-Ph-BPE. The synthetic utility of these two enantioselective protocols is further demonstrated through conducting various stereospecific and site-selective transformations of the enantioenriched organoboron products, including concise synthesis of bioactive molecules.
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Affiliation(s)
- Wenrui Zheng
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Department of Chemistry, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), and Tianjin Collaborative Innovation Centre of Chemical Science & Engineering, Tianjin University, Tianjin 300072, China
| | - Yuhan Cao
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Boon Beng Tan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Yifan Wang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Shaozhong Ge
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Yixin Lu
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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3
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Shen HC, Aggarwal VK. Iridium-Catalyzed Stereocontrolled C(sp 3)-C(sp 3) Cross-Coupling of Boronic Esters and Allylic Carbonates Enabled by Boron-to-Zinc Transmetalation. J Am Chem Soc 2025; 147:5583-5589. [PMID: 39912599 PMCID: PMC11848825 DOI: 10.1021/jacs.4c17931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2024] [Revised: 01/28/2025] [Accepted: 01/31/2025] [Indexed: 02/07/2025]
Abstract
The stereocontrolled C(sp3)-C(sp3) cross-coupling represents a considerable challenge of great contemporary interest. While this has been achieved through the reactions of boronate complexes with π-allyl iridium complexes, such reactions suffered from a limited substrate scope. We now report that following transmetalation from boronate complexes to organozinc reagents enables previously unreactive substrates to engage in stereocontrolled C(sp3)-C(sp3) cross-coupling. The broader substrate scope has enabled their application to the synthesis of biologically active molecules. The organozinc reagents react through a stereoinvertive coupling pathway with π-allyl iridium complexes, in contrast to reactions with other electrophiles that occur with retention of stereochemistry. The reaction uniquely combines the enantiospecific reactivity of an enantioenriched organometallic nucleophile with the enantioselective engagement of a racemic electrophile, enabling access to all stereoisomers.
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Affiliation(s)
- Hong-Cheng Shen
- School of Chemistry, University
of Bristol, Cantock’s
Close, Bristol BS8 1TS, U.K.
| | - Varinder K. Aggarwal
- School of Chemistry, University
of Bristol, Cantock’s
Close, Bristol BS8 1TS, U.K.
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4
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Adak S, Hazra PS, Fox CB, Brown MK. Boron Enabled Directed [2+2]- and Dearomative [4+2]-Cycloadditions Initiated by Energy Transfer. Angew Chem Int Ed Engl 2025; 64:e202416215. [PMID: 39508634 PMCID: PMC11753935 DOI: 10.1002/anie.202416215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Indexed: 11/15/2024]
Abstract
A strategy for the photosensitized [2+2]-cycloaddition between styrenyl dihaloboranes and unactivated allylamines to access cyclobutylboronates with control of stereochemistry and regiochemistry is presented. The success of the reaction relies on the temporary coordination between in situ generated dihaloboranes and amines under mild reaction conditions. In addition, cyclobutanes with varying substitution patterns have been prepared using N-heterocycles as directing group. Manipulation of the C-B bond allows for the synthesis of a diverse class of cyclobutanes from simple precursors. Moreover, these reactions lead to the synthesis of complex amines and heteroaromatic compounds, which have significant utility in medicinal chemistry. Finally, a dearomative [4+2]-cycloaddition of naphthalenes using a boron-enabled temporary tethering strategy has also been uncovered to synthesize complex 3-dimensional borylated building blocks.
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Affiliation(s)
- Souvik Adak
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave. Bloomington, IN 47401, US
| | - Partha Sarathi Hazra
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave. Bloomington, IN 47401, US
| | - Carter B. Fox
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave. Bloomington, IN 47401, US
| | - M. Kevin Brown
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave. Bloomington, IN 47401, US
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5
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Ng S, Howshall C, Ho TN, Mai BK, Zhou Y, Qin C, Tee KZ, Liu P, Romiti F, Hoveyda AH. Catalytic prenyl conjugate additions for synthesis of enantiomerically enriched PPAPs. Science 2024; 386:167-175. [PMID: 39388539 PMCID: PMC11825173 DOI: 10.1126/science.adr8612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Accepted: 09/09/2024] [Indexed: 10/12/2024]
Abstract
Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of >400 natural products with a broad spectrum of bioactivity, ranging from antidepressant and antimicrobial to anti-obesity and anticancer activity. Here, we present a scalable, regio-, site-, and enantioselective catalytic method for synthesis of cyclic β-prenyl ketones, compounds that can be used for efficient syntheses of many PPAPs in high enantiomeric purity. The transformation is prenyl conjugate addition to cyclic β-ketoesters promoted by a readily accessible chiral copper catalyst and involving an easy-to-prepare and isolable organoborate reagent. Reactions reach completion in just a few minutes at room temperature. The importance of this advance is highlighted by the enantioselective preparation of intermediates previously used to generate racemic PPAPs. We also present the enantioselective synthesis of nemorosonol (14 steps, 20% yield) and its one-step conversion to another PPAP, garcibracteatone (52% yield).
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Affiliation(s)
- Shawn Ng
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Casey Howshall
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Thanh Nhat Ho
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Yuebiao Zhou
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Can Qin
- Supramolecular Science and Engineering Institute, University of Strasbourg, 67000 Strasbourg, France
| | - Kai Ze Tee
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Filippo Romiti
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
- Supramolecular Science and Engineering Institute, University of Strasbourg, 67000 Strasbourg, France
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Amir H. Hoveyda
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
- Supramolecular Science and Engineering Institute, University of Strasbourg, 67000 Strasbourg, France
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6
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Xu N, Holmgren JL, Morken JP. Site-Selective Activation and Stereospecific Functionalization of Bis(boronic Esters) Derived from 2-Alkenes: Construction of Propionates and Other 1,2-Difunctional Motifs. Angew Chem Int Ed Engl 2024; 63:e202408436. [PMID: 38924653 PMCID: PMC11881804 DOI: 10.1002/anie.202408436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/21/2024] [Accepted: 06/25/2024] [Indexed: 06/28/2024]
Abstract
Non-directed regioselective activation of bis(boronic esters), followed by functionalization, is reported. A bulky activator is shown to selectively activate the less hindered boronic ester enabling it to undergo stereospecific cross-coupling to a variety of electrophiles. This steric-based regioselectivity provides a simple and efficient method to prepare highly functionalized, enantiomerically enriched products starting from simple alkenes.
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Affiliation(s)
- Ningxin Xu
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA
| | - John L. Holmgren
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA
| | - James P. Morken
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA
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7
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Zhang M, Chapman M, Sarode BR, Xiong B, Liang H, Chen JK, Weerapana E, Morken JP. Catalytic asymmetric synthesis of meta benzene isosteres. Nature 2024; 633:90-95. [PMID: 39169193 PMCID: PMC11878547 DOI: 10.1038/s41586-024-07865-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 07/22/2024] [Indexed: 08/23/2024]
Abstract
Although aromatic rings are common elements in pharmaceutically active compounds, the presence of these motifs brings several liabilities with respect to the developability of a drug1. Nonoptimal potency, metabolic stability, solubility and lipophilicity in pharmaceutical compounds can be improved by replacing aromatic rings with non-aromatic isosteric motifs2. Moreover, whereas aromatic rings are planar and lack three-dimensionality, the binding pockets of most pharmaceutical targets are chiral. Thus, the stereochemical configuration of the isosteric replacements may offer an added opportunity to improve the affinity of derived ligands for target receptors. A notable impediment to this approach is the lack of simple and scalable catalytic enantioselective syntheses of candidate isosteres from readily available precursors. Here we present a previously unknown palladium-catalysed reaction that converts hydrocarbon-derived precursors to chiral boron-containing nortricyclanes and we show that the shape of these nortricyclanes makes them plausible isosteres for meta disubstituted aromatic rings. With chiral catalysts, the Pd-catalysed reaction can be accomplished in an enantioselective fashion and subsequent transformation of the boron group provides access to a broad array of structures. We also show that the incorporation of nortricyclanes into pharmaceutical motifs can result in improved biophysical properties along with stereochemistry-dependent activity. We anticipate that these features, coupled with the simple, inexpensive synthesis of the functionalized nortricyclane scaffold, will render this platform a useful foundation for the assembly of new biologically active agents.
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Affiliation(s)
- Mingkai Zhang
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
| | - Matthew Chapman
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
| | - Bhagyesh R Sarode
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Bingcong Xiong
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
| | - Hao Liang
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
| | - James K Chen
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA.
- Department of Developmental Biology, Stanford University, Stanford, CA, USA.
- Department of Chemistry, Stanford University, Stanford, CA, USA.
| | | | - James P Morken
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA.
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8
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Liang H, Berwanger MR, Morken JP. Stereospecific Phosphination and Thioetherification of Organoboronic Esters. J Am Chem Soc 2024; 146:18873-18878. [PMID: 38954635 PMCID: PMC11877655 DOI: 10.1021/jacs.4c06526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Alkyllithium-activated organoboronic esters are found to undergo stereospecific phosphination with copper chloride and chlorophosphines. They also react with thiolsulfonate electrophiles under copper catalysis. These reactions enable stereospecific phosphination and thiolation of organoboronic esters, which are further applied in preparation of chiral ligands and biologically active molecules.
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Affiliation(s)
- Hao Liang
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Michael R Berwanger
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - James P Morken
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
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9
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Zhang YY, Zhang Y, Xue XS, Qing FL. Reversal of the Regioselectivity of Iron-Promoted Hydrogenation and Hydrohalogenation of gem-Difluoroalkenes. Angew Chem Int Ed Engl 2024; 63:e202406324. [PMID: 38637292 DOI: 10.1002/anie.202406324] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 04/17/2024] [Indexed: 04/20/2024]
Abstract
The reaction regioselectivity of gem-difluoroalkenes is dependent on the intrinsic polarity. Thus, the reversal of the regioselectivity of the addition reaction of gem-difluoroalkenes remains a formidable challenge. Herein, we described an unprecedented reversal of regioselectivity of hydrogen atom transfer (HAT) to gem-difluoroalkenes triggered by Fe-H species for the formation of difluoroalkyl radicals. Hydrogenation of the in situ generated radicals gave difluoromethylated products. Mechanism experiments and theoretical studies revealed that the kinetic effect of the irreversible HAT process resulted in the reversal of the regioselectivity of this scenario, leading to the formation of a less stable α-difluoroalkyl radical regioisomer. On basis of this new reaction of gem-difluoroalkene, the iron-promoted hydrohalogenation of gem-difluoroalkenes for the efficient synthesis of aliphatic chlorodifluoromethyl-, bromodifluoromethyl- and iododifluoromethyl-containing compounds was developed. Particularly, this novel hydrohalogenation of gem-difluoroalkenes provided an effect and large-scale access to various iododifluoromethylated compounds of high value for synthetic application.
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Affiliation(s)
- Yu-Yang Zhang
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
| | - Yuchen Zhang
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
| | - Xiao-Song Xue
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
| | - Feng-Ling Qing
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
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10
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Shen HC, Wang ZS, Noble A, Aggarwal VK. Simultaneous Stereoinvertive and Stereoselective C(sp 3)-C(sp 3) Cross-Coupling of Boronic Esters and Allylic Carbonates. J Am Chem Soc 2024; 146:13719-13726. [PMID: 38721780 PMCID: PMC11117407 DOI: 10.1021/jacs.4c03686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 05/03/2024] [Accepted: 05/03/2024] [Indexed: 05/23/2024]
Abstract
With increasing interest in constructing more three-dimensional entities, there has been growing interest in cross-coupling reactions that forge C(sp3)-C(sp3) bonds, which leads to additional challenges as it is not just a more difficult bond to construct but issues of stereocontrol also arise. Herein, we report the stereocontrolled cross-coupling of enantioenriched boronic esters with racemic allylic carbonates enabled by iridium catalysis, leading to the formation of C(sp3)-C(sp3) bonds with single or vicinal stereogenic centers. The method shows broad substrate scope, enabling primary, secondary, and even tertiary boronic esters to be employed, and can be used to prepare any of the four possible stereoisomers of a coupled product with vicinal chiral centers. The new method, which combines the simultaneous enantiospecific reaction of a chiral nucleophile with the enantioselective reaction of a chiral electrophile in a single process, offers a solution for stereodivergent cross-coupling of two C(sp3) fragments.
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Affiliation(s)
| | | | - Adam Noble
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Varinder K. Aggarwal
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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11
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Posz JM, Sharma N, Royalty PA, Liu Y, Salome C, Fessard TC, Brown MK. Synthesis of Borylated Carbocycles by [2 + 2]-Cycloadditions and Photo-Ene Reactions. J Am Chem Soc 2024; 146:10142-10149. [PMID: 38536870 PMCID: PMC11041674 DOI: 10.1021/jacs.4c01557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Saturated bicyclic compounds make up a valuable class of building blocks in the development of agrochemicals and pharmaceuticals. Here, we present the synthesis of borylated bicyclo[2.1.1]hexanes via crossed [2 + 2]-cycloaddition. Due to the presence of the C-B bond, a variety of structures can be easily prepared that are not accessible by other methods. Moreover, a rare photo-ene reaction is also disclosed, allowing for the diastereoselective synthesis of trisubstituted borylated cyclopentanes.
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Affiliation(s)
- Jarett M Posz
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Neetu Sharma
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Paige A Royalty
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Yanyao Liu
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Christophe Salome
- SpiroChem AG, Rosental Area, WRO-1047-3, Mattenstrasse 22, Basel 4058, Switzerland
| | - Thomas C Fessard
- SpiroChem AG, Rosental Area, WRO-1047-3, Mattenstrasse 22, Basel 4058, Switzerland
| | - M Kevin Brown
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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12
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Zheng W, Tan BB, Ge S, Lu Y. Enantioselective Copper-Catalyzed Ring-Opening Diboration of Arylidenecyclopropanes to Access Chiral Skipped 1,4- and 1,3-Diboronates. J Am Chem Soc 2024; 146:5366-5374. [PMID: 38354313 DOI: 10.1021/jacs.3c12675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
Two enantioselective approaches to synthesize chiral skipped diboronate compounds have been developed, relying on copper-catalyzed one-pot asymmetric ring-opening diboration of arylidenecyclopropanes. A wide range of arylidenecyclopropanes react smoothly with HBpin in the presence of CuOAc and (R)-DTBM-Segphos, affording chiral 1,4-diboronates with high enantioselectivity (up to 99% ee). Meanwhile, a variety of arylidenecyclopropanes react selectively with HBpin and B2pin2 in the presence of CuOAc and (S,S)-Ph-BPE with the sequential addition of MeOH, providing chiral 1,3-diboronates with high enantioselectivity (up to 98% ee). These enantioenriched 1,3- and 1,4-diboronates can undergo various enantiospecific transformations with minimal loss of their enantiopurity. Mechanistic studies reveal that these two diboration processes start with CuH-catalyzed ring-opening hydroboration of arylidenecyclopropanes to form a mixture of Z/E-homoallyl boronate intermediates, which subsequently undergo enantioselective CuH-catalyzed second hydroboration or Cu-Bpin-catalyzed protoboration to produce chiral 1,4-diboronates or 1,3-diboronates, respectively.
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Affiliation(s)
- Wenrui Zheng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Boon Beng Tan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Shaozhong Ge
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Yixin Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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13
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Yuan WJ, Tong CL, Xu XH, Qing FL. Copper-Mediated Oxidative Chloro- and Bromodifluoromethylation of Phenols. J Am Chem Soc 2023; 145:23899-23904. [PMID: 37877952 DOI: 10.1021/jacs.3c08858] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
The first oxidative chloro- and bromodifluoromethylation of phenols with (CH3)3SiCF2X and CuX (X = Cl or Br) in the presence of Selectfluor under mild reaction conditions was developed. This protocol provided a practical and efficient method for the synthesis of a diverse range of biologically valuable and synthetically challenging chloro- and bromodifluoromethyl aryl ethers. Preliminary mechanistic studies suggest that this reaction proceeded through a difluorocarbene-involved oxidative coupling process.
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Affiliation(s)
- Wen-Juan Yuan
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China
| | - Chao-Lai Tong
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China
| | - Xiu-Hua Xu
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China
| | - Feng-Ling Qing
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China
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14
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Liang H, Morken JP. Substrate Plasticity Enables Group-Selective Transmetalation: Catalytic Stereospecific Cross-Couplings of Tertiary Boronic Esters. J Am Chem Soc 2023; 145:20755-20760. [PMID: 37651751 PMCID: PMC10924285 DOI: 10.1021/jacs.3c07129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Activation of enantiomerically enriched tertiary alkylboronic esters with adamantyllithium generated in situ enables stereoretentive boron-to-copper transmetalation. The resulting alkylcopper species can undergo cross-coupling reactions with an array of electrophiles to furnish synthetically useful compounds bearing quaternary stereocenters. DFT calculations of the transmetalation process provide insights for reactivity and selectivity.
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Affiliation(s)
- Hao Liang
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - James P Morken
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States
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