RETENTION STEREOCHEMISTRY IN LIGAND COUPLING REACTION OF OPTICALLY-ACTIVE (1R)-PHENYLETHYL 2-QUINOLYL (R)-SULFOXIDE AND (S)-SULFOXIDE WITH METHYLMAGNESIUM BROMIDE

Reactions of (+)-(1R)-phenylethyl 2-quinolyl (R)-sulfoxide 7a and (-)- (1R)-phenylethyl 2-quinolyl (S)-sulfoxide 7b with methylmagnesium brom ide were examined. The reaction gave (R)-2-(1-phenylethyl)quinoline 9 as a ligand-coupling product, and a mixture of methyl(1R)-phenylethyl (R)- and (S)-sulfoxide 11a and 11b as ligand exchange products. The ot her (S) stereoisomer at the 1-phenylethyl carbon center was not detect ed in the reaction products. That is, both the ligand coupling and lig and exchange reactions proceeded with retention of configuration at th e asymmetric carbon center.