Cyclisation of α-(o-alkenylaryl)diazoalkanes: a route to 2,3-benzodiazepines via a novel 1,7-electrocyclic ring closure
Abstract
α-(o-Alkenylaryl)diazoalkanes, generated from tosylhydrazone salts, cyclise to 1H-2,3-benzodiazepines in high yield. These products isomerise to the 5H-isomers under basic conditions. The energy barriers to ring inversion for both isomers have been estimated from n.m.r. spectroscopic data.