Stereoselective Synthesis of the Epimeric Δ7-Tetrahydrocannabinols
Both C9 epimers of Δ7-THC (3 and 4) have been synthesized from Δ8-THC methyl ether (12). Hydroboration of 12 gave a mixture of stereoisomeric 8-hydroxyhexahydrocannabinols. The 8α-ol was converted into the 9β-methyl epimer (4) of Δ7-THC, while the 8β-ol was converted into 3. Molecular modeling indicated that 4 should have significant cannabinoid activity, while 3 was predicted to be weakly active. These predictions were borne out by both in vitro and in vivo pharmacology.