HIGHLY STEREOSELECTIVE PALLADIUM-CATALYZED COUPLING REACTIONS OF CAPTODATIVE OLEFINS ACETYLVINYL ARENECARBOXYLATES

The palladium-catalyzed reaction of the captodative olefin 3-(p-nitrob enzoyloxy)-3-buten-2-one (1a) with aryl and vinyl halides gave coupled products 4-aryl- and 4-vinyl-3-(p-nitrobenzoyloxy)-3-buten-2-ones, 4 and 6 respectively, with high Z stereoselection. (Ph(3)P)(2)PdCl2 also catalyzed cross-coupling alkylation, phenylation and vinylation with trialkylorganostannanes and bromo olefin (Z)-4-bromo-3-(p-nitrobenzoyl oxy)-3-buten-2-one (2), providing the corresponding trisubstituted alk enes. For the preparation of n-butyl substituted derivative (2)-3-(p-n itrobenzoyloxy)-3-octen-2-one (8b), the transmetallation with n-BuZnCl was a more efficient method. Retention of the Z configuration of 2 wa s in all cases maintained.