Ligand Effects on the Pd-Catalyzed Cross-Coupling Reaction of 3-Iodoalk-2-enoates with Propargyl/1,2-Allenylic Metallic Species: An Efficient Regiodivergent Synthesis of 2,4,5-Trienoates

摘要

Transition-metal-catalyzed cross-coupling reactions between organic halides or pseudohalides with main-group metal species has become a powerful tool for the efficient construction of CC bonds both in academia and industry.[1]In most cases, these cross-coupling reactions do not have regioselectivity problems. For cross-coupling reactions involving propargyl/1,2-allenyl metal species, however, the issue of regioselectivity arises.[2, 3] Over the past few years, we have studied the Negishi coupling reaction[4] involving propargyl/ 1,2-allenyl metal species to afford allenes or alkynes in a highly selective manner (Scheme 1). We found a dramatic dependence of regioselectivity on the steric factors of both Scheme 1. The two complementary modes of Negishi cross-coupling involving propargyl/1,2-allenyl metallic species.