Chemoselective epoxidation of electron-deficient olefins with molecular oxygen via conjugated olefins epoxidation and BHT hydroxylation

The chemoselective epoxidation of electron-deficient olefins in the presence of electron-rich alkene moieties is reported. This chemoselective epoxidation strategy undergoes a conjugated olefin epoxidation and BHT hydroxylation process to give various useful oxiranes in high yields, especially for the 2-substituted 2-trifluoromethyloxiranes. Importantly, this protocol features mild conditions, is transition-metal free, operationally simple, and gram-scalable, and tolerates diverse functional groups. Drug candidate HSD-16 is synthesized smoothly by this protocol. Mechanism studies indicate molecular oxygen is the terminal oxidant and the O-source of the oxiranes.