Delta-9-Tetrahydrocannabinolic Acid B: A Mechanism for its Formation in Cannabis

There appears to be consensus among Cannabis biologists that delta-9-tetrahydrocannabinolic acid A (THCA-A) is the exclusive product of the enzyme THCA synthase. This then leaves an open question for formation of the THCA-A structural isomer, delta-9-tetrahydrocannabinolic acid B (THCA-B), discovered as a minor product in Cannabis in 1969. With no reasonable biochemical pathway to explain the presence of THCA-B in Cannabis, a synthetic route was next considered. Using established literature precedent, a photochemical mechanism has been proposed for the conversion of THCA-A to cannabidiolic acid (CBDA), followed by conversion of CBDA to THCA-B employing bond-breaking and bond-forming reactions.

Automated summary

There is a minor structural isomer called THCA-B in Cannabis, and currently no reasonable biochemical pathway has been found to explain its presence. It is generally believed that THCA-A is the exclusive product of THCA synthase. Therefore, a synthetic route proposing a photochemical mechanism has been suggested to convert THCA-A to CBDA, and then convert CBDA to THCA-B.