lsocoumarins: Part III-Synthesis of 3,4·Dimethylisocoumarins

Synthesis of 3,4-dimethylisocoumarins by effecting cyclodehydration of α-methylacetonyl esters of m-hydroxybenzoic acid and of its derivatives has been developed. Action of aq. NaOH on these isocoumarins has led to the synthesis of (±) α-methyl- α-(2-carboxyphenyl) acetone derivatives which cyclodehydrate readily to give the original isocoumarins. Oxidation of these acetone derivatives with sodium hypobromite has furnished the corresponding (±) α-methyl-homophthalic acids. Action of ammonia on these isocoumarins furnished the corresponding isoquinolone derivatives.