A method is provided for the synthesis of (-)-trans-.sup.9-tetrahydrocannabivarin (.sup.9-THCV) and analogs thereof such that in the reaction product, the molar ratio of the .sup.9 isomer to incidentally formed .sup.8 isomers is greater than 4:1. Synthesis is carried out by combining a selected cannabinoid reactant, e.g., cannabidivarin (CBDV) or an analog thereof, with an acid in a solvent for the cannabinoid reactant, wherein the acid comprises (i) a Lewis acid having an acid softness index value in the range of 10 G.sup.0.sub.f, M.sup.n+ to 150 G.sup.0.sub.f, M.sup.n+, (ii) a Brnsted acid having a pKa in the range of 4.0 to +4.0, or (iii) a combination of (i) and (ii), under reaction conditions comprising a reaction temperature in the range of 0 C. to 25 C. and a reaction time in the range of 1 hour to 24 hours. The reaction is thereafter quenched with base and the solvent removed, wherein the crude reaction product so provided may be purified, e.g., chromatographically purified. Also provided is a method for synthesizing .sup.9-THCV that further includes synthesis of the cannabinoid reactant. The invention additionally provides novel cannabinoid compositions that may be synthesized using the aforementioned methodology.

A method is provided for the synthesis of (-)-trans-.sup.9-tetrahydrocannabivarin (.sup.9-THCV) and analogs thereof such that in the reaction product, the molar ratio of the .sup.9 isomer to incidentally formed .sup.8 isomers is greater than 4:1. Synthesis is carried out by combining a selected cannabinoid reactant, e.g., cannabidivarin (CBDV) or an analog thereof, with an acid in a solvent for the cannabinoid reactant, wherein the acid comprises (i) a Lewis acid having an acid softness index value in the range of 10 G.sup.0.sub.f, M.sup.n+ to 150 G.sup.0.sub.f, M.sup.n+, (ii) a Brnsted acid having a pKa in the range of 4.0 to +4.0, or (iii) a combination of (i) and (ii), under reaction conditions comprising a reaction temperature in the range of 0 C. to 25 C. and a reaction time in the range of 1 hour to 24 hours. The reaction is thereafter quenched with base and the solvent removed, wherein the crude reaction product so provided may be purified, e.g., chromatographically purified. Also provided is a method for synthesizing .sup.9-THCV that further includes synthesis of the cannabinoid reactant. The invention additionally provides novel cannabinoid compositions that may be synthesized using the aforementioned methodology.