CYCLOADDITION REACTION OF BENZOCYCLOPROPENE WITH AROMATIC NITRILE OXIDES: A SYNTHETIC ENTRY INTO A BRIDGED OXAZONINE

9-Aryl-7-oxa-8-azatricyclo[4.3.1.0]deca-2,4,8-trienes (Ia and Ib) were synthesized by the cycloaddition reaction of benzocyclopropene with benzonitrile oxide and mesitonitrile oxide, respectively. The closed norcaradiene structures were preferable to the opened bridged oxazonine isomers in the range of 25–120°C.