An unusual base-mediated ring contraction reaction of benzopyrans to benzofurans

✍ Scribed by Derek R. Buckle; Andrew Faller; Ivan L. Pinto; David G. Smith

• Publisher: Elsevier Science
• Year: 1992
• Tongue: French
• Weight: 233 KB
• Volume: 33
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)91873-2

✦ Synopsis

The reaction of electron &jicient pyrroles and pyrazoles with tram 3-bromo-&cyano-3,4-dihydro-2,2-dimethyl-ZH-I-benzopyrun-4-al under basic conditions results in the formation of 2-isopropylbenzofurans by a mechanism which appears to be dependent on the rate of the competitive dehydration reaction ieading to rhe corresponding benzopyrans.