There has been considerable research into the synthesis of THC and its
analogues. A prominent figure in the early work in the 40's is Roger
Adams. Many THC analogues have been synthesized, some with potencies
(supposedly) 512 times that of the natural THC. The two areas on the
structure that are the pharmacological functional groups are the long
alkyl chain on the aromatic ring and variations on the nonaromatic ring.
Acetylation of the hydroxyl usually produces a more potent compound. Look
in the Merck Index under Nabilone, Synhexyl, tetrahydrocannabinol,
cannabinol, and cannabidiol. This is a good start on cannabinoid
chemistry, but there seem to be myriad articles on nitrogen analogues of
all sorts and other heteroatoms like sulfur. Too many for me to mention
all of the references.
 Another author worth mentioning is T. Petrzilka (don't ask me how to
pronounce that...). (Helv. Chim Acta 52, 1102 (1969); 50, 719 (1967);
1416 (1967); 2111 (1967))

St. Anthony