On 4-Keto-3:4-Dihydroisocoumarin

Experiments to synthesise Perkin's 5:6-dimethoxy-4-keto-3 :4- dihydroisocoumarin have been described. 4-Keto-3:4-dihydroisocoumarin has been synthesised by an adaptation of Cutiaus, reaction and also by chromic acid oxidation of 3:4 dihydroisocoumarin. A number of condensation products of 4-Keto-3:4- dihydroisocoumarin with aromatic aldehydes including Zincke's aldehyde have also been described. The m-methoxybenzylidene derivative was converted into 6'-rnetbaxyindeno (2':3'-.3:4)isocoumarin which represents a new ring system.