ANODIC-OXIDATION OF 3,5-DIHALOGENOTYROSINES AS A MODEL REACTION FOR THE BIOGENESIS OF THE CAVERNICOLINS, METABOLITES OF THE VERONGID SPONGEAPLYSINA-CAVERNICOLA

Anodic oxidation of 3,5-dibromo-4-methoxyphenylalanine methyl ester 3, led to cavernicolin 3a,7,7a-tetrahydro-3a-hydroxyindole-2,6(1H)-dione ] model compounds although equilibration to all four possible stereois omers 4alpha, 4beta, 5alpha and 5beta was a special characteristic of the model compounds only. This may constitute a new model for the biog enesis of the cavernicolins as an alternative to a spirolactone route from oxidation of amino-protected tyrosines. Chemical oxidation gave p oor results.