Palladium-Catalyzed C−C Bond Formation: Synthesis of 1,1-Dialkylbuta-1,3-dienes and β-Phenylstyrenes via Organoboron Intermediates

α,β-Unsaturated and α-phenyl acetals show different reactivity when treated with LIC-KOR superbase and trialkylboranes, in the presence of the reagent system PdL4-ArX (Suzuki−Miyaura cross-coupling conditions). In particular, unsaturated acetals yield gem-dialkylbutadienes via the formation of an intermediate π-allyl complex that facilitates an anionotropic alkyl migration; in the case of α-phenyl derivatives, the corresponding cross-coupling products are recovered. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)