Nickel-catalyzed asymmetric ?-arylation and heteroarylation of ketones with chloroarenes: effect of halide on selectivity, oxidation state, and room-temperature reactions.

ABSTRACT: We report the ?-arylation of ketones with a range of aryl chlorides with enantioselectivities from 90 to 99% ee catalyzed by the combination of Ni(COD)(2) and (R)-BINAP and the coupling of ketones with a range of heteroaryl chlorides with enantioselectivities up to 99% ee catalyzed by Ni(COD)(2) and (R)-DIFLUORPHOS. The analogous reactions of bromoarenes occur with much lower enantioselectivities. Mechanistic studies showed that the difference in the rates of decomposition of the arylnickel(II) halide intermediates to {[(R)-BINAP]NiX}(2) likely accounts for the difference in the enantioselectivities of the reactions of bromoarenes and chloroarenes. This catalyst decomposition can be overcome by conducting the reactions with [(R)-BINAP]Ni(?(2)-NC-Ph) (4), which undergoes oxidative addition to haloarenes at room temperature.

SUBMITTER: Ge S 

PROVIDER: S-EPMC3214653 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature