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

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.

Automated summary

An efficient and facile method utilizing PTSA catalyst has been developed for the synthesis of 2,3-dihydronaphtho[2,3-b]furan and 3,4-dihydro-2H-benzo[g]chromene. This methodology shows high yield cyclization reaction of ortho-oxalate-, ortho-keto-, and ortho-formyl arylacetylenols. It is also successfully applied to the large-scale synthesis of the naphthofuran skeleton.