Stille Coupling of Stereochemically Defined α-Sulfonamidoorganostannanes

Addition of tributylstannylmetallics to (R)-tert-butanesulfonimine derivatives of arylaldehydes provides α-sulfinamidostannanes with high (>98% de) diastereoselectivities. Oxidation of these compounds with m-CPBA gives α-sulfonamidostannanes which undergo Pd/Cu-catalyzed Stille-type couplings with benzoyl chloride. Best yields are achieved using the electron-rich tris(2,4,6-trimethoxyphenyl)phosphine as the ligand. Inversion of configuration at the benzylic carbon is observed.