The enzymatic oxidation of phenolic tetrahydroisoquinoline-1-carboxylic acids

Tetrahydroisoquinoline-1-carboxylic acids with a 6- or 7-hydroxy substituent undergo oxidative decarboxylation on treatment with horseradish peroxidase or fungal laccase to give high yields of the corresponding 3,4-dihydroisoquinolines. Attempts to apply this reaction to the formation of an aporphine were unsuccessful.