Abnormal products in the Bischler–Napieralski isoquinoline synthesis

Abstract

Reaction of N-[2-(4-methoxyphenyl)ethyl]benzamides with phosphorus pentoxide (and phosphoryl chloride) gives 7-methoxy-1-phenyl-3,4-dihydroisoquinolines (a normal Bischler–Napieralski reaction product) and 6-methoxy-1-phenyl-3,4-dihydroisoquinolines (an abnormal reaction product). The reaction mechanism is discussed.