Chromic anhydride-3, 5-dimethylpyrazole complex: an efficient reagent for oxidation of steroidal estrogens to 6-oxo-derivatives.

An efficient procedure for the oxidation of steroidal estrogens to the corresponding 6-oxo-derivatives is described. The oxidative process involves the use of 3,5-dimethylpyrazole-chromium trioxide complex at low temperature (-20 degrees). Under these conditions, only the 6-oxo-derivative and the unreacted starting material were obtained and the latter could be subjected to oxidation once again to obtain additional amount of 6-oxo-derivative.