Abstract:
A [4+3] annulation of o-phenylenediamines with primary nitroallylic acetates affords
nitrobenzodiazepines (NBDZs) in good to excellent yield. The reaction which proceeds in
MeOH at room temperature in the absence of any base or catalyst involves a cascade SN2 Nnitroallylation-
intramolecular aza-Michael addition sequence. In the case of mono-N-arylated ophenylenediamines
and o-aminobenzamides, the reaction stops at the SN2 stage affording
nitroallylic amines. On the other hand, reaction of o-aminobenzamides with secondary
nitroallylic acetates delivers SN2’ products. Formation of stable SN2 and SN2’ products provides
insights into the reactivity of primary and secondary nitroallylic acetates and also the mechanism
of formation of nitrobenzodiazepines.
