Liu M, Le N, Uyeda C. Nucleophilic Carbenes Derived from Dichloromethane.
Angew Chem Int Ed Engl 2023;
62:e202308913. [PMID:
37661190 PMCID:
PMC10591934 DOI:
10.1002/anie.202308913]
[Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/20/2023] [Accepted: 09/01/2023] [Indexed: 09/05/2023]
Abstract
Nickel PyBox catalysts promote nucleophilic cyclopropanation reactions using CH2 Cl2 as a methylene source and Mn as a stoichiometric reductant. The substrate scope includes a broad range of alkenes bearing electron-withdrawing substituents, including esters, amides, ketones, nitriles, sulfones, phosphonate esters, trifluoromethyl groups, and electron-deficient arenes. Enantioselective cyclopropanations of α,β-unsaturated esters have been developed using chiral PyBox ligands. Mechanistic studies suggest the intermediacy of a (PyBox)Ni=CH2 species, which adds to the alkene by a stepwise [2+2]-cycloaddition/C-C reductive elimination mechanism. DFT models provide a rationale for the nucleophilic character of the nickel carbene and the sense of enantioinduction.
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