Formation of hydridocobalt(iii) phthalocyanine by reaction of cobalt(ii) phthalocyanines with sodium borohydride and its reactions with antioxidant isoflavones

Abstract

The reduction of substituted isoflavones with sodium borohydride catalyzed by cobalt(II) phthalocyanines has been achieved efficiently to yield cis- and trans-isoflavan-4-ols under mild conditions via the formation of a hydridocobalt(III) phthalocyanine intermediate. The hydroxy isoflavones react with sodium borohydride to form the corresponding phenolate moiety and thereby prevent the formation of a hydridocobalt(III) phthalocyanine intermediate which inhibits its reduction to corresponding isoflavan-4-ols.