Copper-Catalyzed Defluorinative Borylation and Silylation of <i>gem</i>-Difluoroallyl Groups
作者:Trevor W. Butcher、Jonathan L. Yang、John F. Hartwig
DOI:10.1021/acs.orglett.0c02321
日期:2020.9.4
Stereodefined (Z)-fluoroalkenes are bioisosteres of amides and synthetic precursors to value-added fluorinated compounds, but their stereoselective synthesis remains challenging. Herein, we report a copper-catalyzed formal SN2′ defluorinative borylation of 3-substituted 3,3-difluoropropenes to form 3-fluoroallylboronic esters in high yields with excellent Z/E ratios. The primary 3-fluoroallylboronic
Nickel-catalyzed reductive cross-coupling of allylic difluorides with aryl iodides was achieved via allylic C−F bond activation. Based on this protocol, a series of γ-arylated monofluoroalkenes were synthesized in moderate to high yields. Mechanistic studies suggest that the C−I bonds of the aryl iodides and the C−F bonds of the allylic difluorides were cleaved via oxidative addition and β-fluorine
A new type of bench-stable yet highly reactive fluoroalkylating reagents, 3,3-difluoroallyl sulfonium salts (DFASs), has been developed. The reaction of DFASs with aromatic and aliphatic zincreagents via copper catalysis provides general and practical access to a wide range of versatile gem-difluoroallylated compounds with high regioselectivity.
Herein, a palladium-catalyzed regioselective alkynylation, esterification, and amination of allylic gem-difluorides via C–F bond activation/transmetallation/β-C elimination or nucleophilic attack has been achieved. This innovative protocol showcases an extensive substrate range and operates efficiently under mild reaction conditions, resulting in high product yields and Z-selectivity. Particularly
A first example of Pd-catalyzed gem-difluoroallylation of organoborons using 3-bromo-3,3-difluoropropene (BDFP) in high efficiency with high alpha/gamma-substitution regioselectivity has been developed. The reaction can also be extended to substituted BDFPs and has advantages of low catalyst loading (0.8 to 0.01 mol %), broad substrate scope, and excellent functional group compatibility, thus providing a facile route for practical application in drug discovery and development.