A concise stereoselective synthesis of the C-aromatic taxane skeleton: an application of novel sequential transacetalation oxonium ene cyclization

Abstract

A three-step sequence for the construction of the C-aromatic taxane nucleus from easily available A-ring unit 2 and C-aromatic unit 3 is reported; SnCl₄ promoted reaction of 4, presumably via the diastereoselective oxonium ene cyclisation reaction of 6a formed in situ, delivers cyclic ether 5a which on treatment with BuⁿLi provides C-aromatic taxane skeleton 8.