Total Synthesis of (−)-Bafilomycin A1: Application of Diastereoselective Crotylboration and Methyl Ketone Aldol Reactions

A careful orchestration of protecting groups is an essential requirement for the total synthesis of the macrolide antibiotic bafilomycin A₁ (1). Key steps were the Suzuki cross-coupling reaction of two advanced, suitably protected intermediates prior to closure of the macrocycle, as well as a highly stereoselective methyl ketone aldol reaction.