Condensation of 5-(1,1-dimethylhexyl)resorcinol (I) with (1S,4R)-4-isopropenyl-1-methyl-2-cyclohexenol (II) under acidic conditions furnishes the tetrahydrocannabinol derivative (III). The phenolic hydroxyl of (III) is then alkylated by iodomethane in the presence of NaOH to afford the target methyl ether.