Heterocyclic nitrogen compounds. Part VI. Preparation of 2,3-dihydro-3-oxospiro{isoindole-1-3′-benzo[b]thiophen}-2′-carboxylic acid SS-dioxide by the Schmidt reaction on benzo[b]naphtho[1,2-d]thiophen-5,6-quinone SS-dioxide

Abstract

The Schmidt reaction on benzo[b]naphtho[1,2-d] thiophen-5,6-quinoneSS-dioxide (I) yields as a main product 2,3-dihydro-3-oxospiro{isoindole-1,3′-benzo[b]thiophen}-2′-carboxylic acid SS-dioxide (II). The product (IVa) of decarboxylatin of (II), has been converted by Raney nickel desulphurisation into 2,3-dihydro-3-methyl-3-phenylisoindol-1-one (Va). The N-methyl derivative of (IVa) has similarly been desulphurised to give 2,3-dihydro-2,3-dimethyl-3-phenylisoindol-1-one (Vc).