A synthesis of herboxidiene

The natural herbicide herboxidiene was constructed from two key fragments using a modified Julia olefination based on the benzothiazolyl sulfone activator. Key steps in the synthesis of the C1-C10 oxane fragment were (a) a modified Julia olefination using a 1-phenyl-1H-tetrazolyl sulfone as-activator and (b) an intramolecular addition of an alkoxide to an alpha,beta-unsaturated eater. Key steps in the synthesis of the C11-C19 polyketide fragment were (a) a directed aldol reaction using a camphor-10,2-sultam as auxiliary; (b) an Ireland-Claisen rearrangement and (c) a hydroxy-directed epoxidation.