Enantiospecific tritium labeling of 28‐homocastasterone

A regiospecific and enantiospecific synthesis of tritium‐labeled 28‐homocastasterone is reported. Appropriate chlorocarbonate, efficiently synthesized from the starting 28‐homocastasterone in an overall yield of 46%, undergoes catalytic tritium dechlorination by the T₂/Pd[0]/Et₃N system, providing 28‐[3β‐³H]homocastasterone, in a good yield, radiochemical purity (>97%), and with a high specific activity (5.8 Ci/mmol).