Base-promoted one-pot sequential phosphite addition and 5- exo -dig cyclization of enynals: A facile route to trisubstituted furans

Abstract

An easy route for the synthesis of trisubstituted furans has been demonstrated. One-pot sequential phosphite (H-phosphonate) addition to alkynylaldehydes (enynals) promoted by tripotassium phosphate leads to trisubstituted furans (phosphono-furans) via 5-exo-dig cyclization of the phosphono-alkynol intermediates. In contrast, in the presence of silver(I) tetrafluoroborate, the reaction using the same substrates leads to a diene product. © Georg Thieme Verlag Stuttgart, New York.