Stereoselective Synthesis of Nonpsychotic Natural Cannabidiol and Its Unnatural/Terpenyl/Tail-Modified Analogues

Here, we report a three-step concise and stereoselective synthesis route to one of the most important phytocannabinoids, namely, (−)-cannabidiol (-CBD), from inexpensive and readily available starting material R-(+)-limonene. The synthesis involved the diastereoselective bifunctionalization of limonene, followed by effective elimination leading to the generation of key chiral p-mentha-2,8-dien-1-ol. The chiral p-mentha-2,8-dien-1-ol on coupling with olivetol under silver catalysis provided regiospecific (−)-CBD, contrary to reported ones which gave a mixture. The newly developed approach was further extended to its structural analogues cannabidiorcin and other tail/terpenyl-modified analogues. Moreover, its opposite isomer (+)-cannabidiol was also successfully synthesized from S-(−)-limonene.