o-N-tosylcarbamoyl-substituted α-diazoacetophenones: their preparation and decomposition

Abstract

A diazo group transfer reaction of tosyl azide with 2-methyl-2a and 2-phenyl-indane-1,3-dione 2b in the presence of triethylamine leads to the isolation of the corresponding o-N-tosylcarbamoylsubstituted α-diazoacetophenones 3a, b as their triethylamine salts 6a, b in fairly good yield. Upon decomposition in boiling benzene or, at room temperature, in water, acetic acid or methylene dichloride in the presence of BF₃·OEt₂, and benzene in the presence of rhodium(II) acetate the diazocarbonyl compounds 6a, b can lead to isoquinoline-1,3-diones, isoquinoline-1,4-diones and 3-hydroxyisoindolones in varying yields. The relative ratio of these resulting products is (highly) dependent upon reaction conditions and their diazo precursor 6a or 6b. The possible reaction pathways involved in the diazoacetophenone 6a, b decompositions are discussed. An X-ray crystal structure analysis of the (S,R; R,S)-diastereoisomer of the isoindolone 7 has been performed.