[12‐3H]‐(±)‐Calanolide A (9) was synthesized in five steps from readily available phloroglucinol (1). Stereoselective Luche reduction of transketone 8 with cerium(III) chloride and sodium borotritide in methanol gave 338 μCi of 9 with a specific activity of 63.0 mCi/mmol.
