The Schmidt reaction with benzocycloalkenones

Abstract

Eighteen 1-indanones, fifteen 1-tetralones, two 1-benzosuberanones, and two benzocyclobutenones, as well as four acetophenones, have been submitted to the Schmidt reaction in sulphuric acid, polyphosphoric acid, or molten trichloroacetic acid, and the ratios of the respective isomeric rearrangement products have been determined. The direction of the rearrangement in the Schmidt reaction with benzocyclobutenones and 1-indanones is strongly affected by the substituents in the aromatic ring in positions para or ortho to the carbonyl group, and by the acid medium used in the reaction. The same influence was observed to a lesser extent, but still markedly, with 1-tetralones. In ketones having a flexible structure, such as 1-benzosuberanones and acetophenones, no appreciable influence of substituents and acid mediums was noted on the direction of migration, giving in all cases predominantly N-aryl amide.