Acid-catalyzed synthesis of 2,3-dihydronaphtho[2,3-b]furan and 3,4-dihydro-2H-benzo[g]chromene derivatives

Abstract

An efficient and facile method for producing 2,3-dihydronaphtho[2,3-b]furan and 3,4-dihydro-2H-benzo[g]chromene has been developed. This methodology utilizes an inexpensive and simple PTSA catalyst for the cyclization reaction of ortho-oxalate-, ortho-keto-, and ortho-formyl arylacetylenols to produce the corresponding products in high yield. This procedure was also successfully applied to the large-scale synthesis of the naphthofuran skeleton, which can be found in various natural products and pharmaceuticals.