The synthesis of both side chain epimers of 1'- (4), 2'- (5), 3'-methyl- (6) and 4'-methyl-Delta(8)- tetrahydrocannabinol (7) has been carried out. The synthetic approach entailed the acid catalyzed condensation of the appropriate substituted resorcinol with menthadienol to provide the Delta(8)-THC analogue. Both isomers of 1'- (4) and 2'-Delta(8)-THC (5) were more potent than Delta(8)-THC, both in vitro and in vivo. The 3'-methyl isomers (6) were approximately equal in potency to Delta(8)-THC, and 4'-methyl-Delta(8)-THC was less potent. There was relatively little difference in potency between the epimers of 4, 5, and 6. (C) 1997, Elsevier Science Ltd.