A simple two-step method for the conversion of [3H]cortisol to [3H]-11-ketotestosterone.

Despite the existence of several protocols, problems appear to persist in the small scale chemical synthesis of radiolabeled 11-ketotestosterone from cortisol. We investigated the possibilities of using the mild oxidant pyridinium dichromate for the oxidative cleavage of the dihydroxyacetone side chain of cortisol and 17 beta-hydroxysteroid dehydrogenase for the subsequent reduction of the resulting 17-keto group. Our protocol has resulted in consistently high yields of both the intermediate, adrenosterone (70-80%), and the product, 11-ketotestosterone (up to 60%). This, taken together with the convenience and relatively low cost of our method, recommends the protocol for its use for the synthesis of [3H]-11-ketotestosterone for endocrine studies.