Stereocontrolled Intramolecular Diels-Alder Reaction of Heterodienes; Studies on the Synthesis of Cannabinoids


  • This work was supported by the Fonds der Chemischen Industrie. We wish to thank Prof. Dr. D. Leibfritz and Dr. M. Feigl, Universität Bremen, for recording the 360-MHz 1H-NMR spectrum and the Dragoco Company, Holzminden, for supplying citronellal.


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The skeleton (4) of tetrahydrocannabinol having translinked rings A and B can be obtained optically pure from the diketone (1) and (R)-citronellal (2). The key step is intramolecular Diels-Alder reaction (up to 20°C!) of the heterodiene intermediate (3).—Derivatives of (4) are of interest, e.g., in the treatment of glaucoma.