Catalytic Asymmetric Cyclopropanation of Enones with Dimethyioxosulfonium Methylide Promoted by a La-Li_3-(Biphenyldiolate)_3 + Nal Complex

摘要

The cyclopropane unit is a common structural motif in biologically active natural and unnatural compounds. Its unique reactivity and structural properties have led chemists to develop a new methodology for cyclopropanation. Among the methods available, cyclopropanation using ylides proceeds chemoselectively with electron deficient olefins. Therefore, the method is complementary to other variants, such as the Simmons—Smith type reaction and the carbenoid-mediated reaction. Catalytic highly enantioselective Simmons—Smith-type and carbenoid-mediated cyclopropanations have been established; however, catalytic asymmetric cyclopropanation of electron deficient olefins with ylides is rare. Aggarwal and Gaunt reported pioneering studies on enantioselective cyclopropanations via the catalytic generation of chiral sulfonium and ammonium ylides.