Synthesis and reactions of benzo[b]furo[2,3-c]pyrylium salts

✍ Scribed by V. I. Dulenko; S. V. Tolkunov

• Publisher: Springer US
• Year: 1987
• Tongue: English
• Weight: 306 KB
• Volume: 23
• Category: Article
• ISSN: 0009-3122
• DOI: 10.1007/bf00475635

✦ Synopsis

A method has been developed for the synthesis of 3-acetonyl-and 3-phenacylbenzo[b]furans by cyclization of l-arloxy-2,4-pentanedlones and l-phenyl-4-aryloxy-1,3-butanediones in polyphosphoric acid. Acylation of 3-acetonyl(phenyl-benzo-[b]furans with aliphatic acid anhydrides in the presence ofperchloric acid gives the benzo[b]furo[2,3-c]pyrylium perchlorates. The recyclization of the pyrylium salts with ammonia, aqueous alkali, and morpholine has been examined.

The synthesis of biologically active compounds from pyrylium salts holds promise. In this connection, the acid-catalyzed cyclization reaction is of interest [i], this having previously provided a number of condensed pyrylium and pyridine salts [2,7].

We here describe the synthesis of some benzo[b]furo[2,3-c]pyrylium salts (Ill-V) by acid catalyzed cyclization