Dextro-gamma-carboxymethyl-gamma-methyl-delta-alpha-butenolide. A 1,2-ring-fission product of 4-methylcatechol by Pseudomonas desmolyticum.

1. (+)-gamma-Carboxymethyl-gamma-methyl-Delta(alpha)-butenolide was isolated from resting-cell cultures of Pseudomonas desmolyticum incubated in the presence of 5-methylsalicylic acid. 2. The structure of this metabolite was deduced from physical and chemical evidence. 3. The isolated compound must be formed in an enzymic reaction since it shows optical activity. 4. The degradative pathway of 4-methylcatechol by Ps. desmolyticum is discussed.