Regioselective Total Synthesis of Furoventalene, a Marine Natural Benzofuran, via the β-Vinylbutenolide Annulation

Article abstract of DOI:10.1021/jo00334a032

The framework of furoventalene (1) was regioselectively constructed from methyl 2-formyl-6-methyl-5-heptenoate (12) and 2,5-dihydro-3-methyl-4-vinyl-2-furanone (10) by consecutive 1,6 conjugate addition and aldol-type cyclization to lead to a diastereomeric mixture of bicyclic butenolides 13a and 13b.Both of the annulation products were transformed into 1 by a sequence of reactions: reduction, hydrolysis, dehydrative decarboxylation, and dehydrogenation via intermediates 14-16.The stereochemistry of the annulation products 13a and 13b is also discussed.