Asymmetric Suzuki cross-couplings of activated secondary alkyl electrophiles: arylations of racemic alpha-chloroamides.
A nickel-catalyzed stereoconvergent method for the enantioselective Suzuki arylation of racemic alpha-chloroamides has been developed. This process provides a unique example of an asymmetric arylation of an alpha-haloamide, an enantioselective arylation of an alpha-chlorocarbonyl compound, and an asymmetric Suzuki reaction with an activated alkyl electrophile or an arylboron reagent. The method is also applicable to the corresponding enantioselective cross-coupling of alpha-bromoamides. The coupling products can be transformed without racemization into enantioenriched alpha-arylcarboxylic acids and primary alcohols. A modest kinetic resolution of the alpha-chloroamide was observed; a mechanistic study indicated that the selectivity may reflect discrimination by the chiral catalyst of the two enantiomeric alpha-chloroamides in an irreversible oxidative-addition process.
Lundin
Pamela M
PM
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Fu
Gregory C
GC
D000473:Alkanes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
D000473:Alkanes; D000577:Amides