The known tetrahydrocannabinol analogue (I) was protected as the silyl ether (II) upon treatment with tert-butyldimethylsilyl chloride and imidazole. Reductive cleavage of the pivaloyl group of (II) by means of LiAlH4 afforded the free allylic alcohol (III). Oxidation with chromic oxide in pyridine led to the aldehyde (IV), which was further oxidized to the acid (V) with sodium chlorite. Finally, removal of the silyl protecting group of (V) employing tetrabutylammonium fluoride furnished the title compound.
The aromatic portion of the molecule is generated by the condensation of 1,6-dimethoxyphenol with 1,1-dimethylheptanol in the presence of methanesulfonic acid at 50 C. The crude product is then esterified with diethyl phosphite and triethylamine with cooling to yield the diethyl phosphate derivative. Reduction with lithium in liquid ammonia produces 1-(1',1'-dimethylheptyl)-3,5-hydroxybenzene (I) which is processed crude to the next step. This involves the condensation of the p-menthenediol (II) with the dimethylheptyl resorcinol (I) catalyzed by p-toluenesulfonic acid to give the dimethylheptyl analog of DELTA8-THC (III). Following acetylation of the phenolic group, the allylic methyl group is oxidized to the aldehyde (IV) using selenium dioxide. Further oxidation to the carboxylic acid is accomplished by the use of sodium chlorite. Finally, ajulemic acid is obtained by removal of the acetyl group with sodium carbonate in aqueous methanol.