Studies of Palladium-Catalyzed Cross-Coupling Reactions for Preparation of Highly Hindered Biaryls Relevant to the Korupensamine/Michellamine Problem

摘要

Pd~0-mediated cross-coupling reactions to construct the highly hindered biaryl bond present in various model systems relevant to korupensamine and michellamine synthesis were studied. Several different arylmetal systems were compared. No coupled product was observed under the Stille (Sn) conditions. Suzuki (B) coupling worked well for the desired system and has been used in the natural product syntheses. Comparable yields have now been obtained with the Negishi (Zn) coupling, where isolation of the intermediate zinc reagents is unnecessary.