Cycloadditions of diphenylnitrilimine with tropone and with tricarbonyltroponeiron. Thermal [1,5] sigmatropic rearrangements of the [π6s+π4s] cycloadducts of 1,3-dipoles with tropone

Abstract

The reaction of diphenylnitrilimine (benzonitrile N-phenylimide) with tropone has been reinvestigated and eight products have been detected. In addition to the [_π6_s+_π4_s] cycloadduct formed by reaction at positions 2 and 7 of tropone, both the regioisomeric [_π2_s+_π4_s] adducts involving positions 2 and 3 and positions 4 and 5 were obtained. The reaction of tricarbonyltroponeiron, which was more reactive than tropone itself, gave a mixture of two regioisomers. The specific [1,5] sigmatropic rearrangement of the [6 + 4] cycloadducts of diphenylnitrilimine and benzonitrile oxide with tropone, which involves selectively the sp² carbon atom instead of either the oxygen or the nitrogen atom of the 1,3-dipole have been also studied.