Efficient synthesis of 2,3,4-trisubstituted furans from the reaction of activated acetylenes with ethyl bromopyruvate in the presence of enaminones

摘要

The reaction of dialkyl acetylenedicarboxylates or diaroylacetylenes with ethyl bromopyruvate in the presence of enaminones led to 2-ethyl 3,4-dialkyl 4-bromo-4,5-dihydro-2,3,4-furantricarboxylates or ethyl 3,4-diaroyl-4-bromo-4,5-dihydro-2-furancarboxylate in excellent yields. These compounds are quantitatively converted to the corresponding 2,3,4-trisubstituted furans by 4-dimethylaminopyridine.