Regioselective Reaction between 3-Ethoxalyl-5-methylcyclopentane-1,2,4-trione and Vinyltriphenylphosphonium Salts: Convenient Synthetic Route to Functionalized Cyclopenta[b]furans†

Abstract

3-Ethoxalyl-5-methylcyclopentane-1,2,4-trione exists, in solution, almost exclusively as the dienol tautomer, which undergoes regioselective intramolecular Wittig reaction with vinyltriphenylphosphonium salts to produce the enol form of dialkyl 4-ethoxalyl-6-methyl-5-oxo-4,5-dihydro-3aH-cyclopenta[ b]furan-2,3-dicarboxylates in moderate yields.