Oxidation with chromium(VI) oxide - pyridine complex. A study of reaction parameters using cholesterol as substrate

Oxidation of cholesterol with chromium(VI) oxide – pyridine complex under various conditions produced cholest-5-en-3-one accompanied by varying amounts of cholest-4-ene-3,6-dione. The efficiency of the oxidation and the product distribution were found to be dependent on the atmosphere, temperature, molar ratio of oxidant to substrate, molar ratio of pyridine to chromium trioxide, the heterocyclic amine used, and the proton source employed. The yield of cholest-5-en-3-one was optimized by oxidation of cholesterol with a ten-fold excess of the monopyridine – chromium(VI) oxide complex in dichloromethane under a nitrogen atmosphere at 0 °C.