Synthesis of deuterium labeled cannabinoids

Several methods for the specific deuteration of cannabinoids are described. Deuteration of the phenolic ring was accomplished by treatment with BF3. Et2O followed by quenching with a solution of Na2 CO3 in D2 O resulting in deuterium incorporation in both the 2 and 4 positions. Regioselective incorporation of deuterium into either the 2 or 4 position of Δ8‐THC was achieved using Florisil spiked with either D2O or H2O. Deuteration at positions 8, 10 and 11 was achieved by addition of DCI gas to the appropriate tetrahydrocannabinol to form 9‐chlorohexahydrocannabinol labeled at either of the above positions, followed by elimination of hydrogen‐ or deuterium chloride with potassium‐tert‐amylate. UV irradiation of specifically labeled Δ8‐THC gave the correspondingly labeled Δ9,11‐THC.