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Synthese von Haschisch‐Inhaltsstoffen. 4. Mitteilung
Author(s) -
Petrzilka T.,
Haefliger W.,
Sikemeier C.
Publication year - 1969
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19690520427
Subject(s) - chemistry , hydrochloric acid , trifluoroacetic acid , picric acid , medicinal chemistry , yield (engineering) , condensation , catalysis , oxalic acid , organic chemistry , stereochemistry , materials science , physics , metallurgy , thermodynamics
(−)‐Cannabidiol has been synthesized from (+)‐ cis ‐ and (+)‐ trans ‐ p ‐menthadien‐(2, 8)‐ol‐(1) and olivetol, using N, N‐dimethylformamide dineopentyl acetal or weak acids, such as oxalic, picric, or maleic acid, as catalysts. Since the chirality of (+)‐ trans ‐ p ‐menthadien‐(2, 8)‐ol‐(1) is known, the above synthesis constitutes an unambiguous prove for the absolute configuration of (−)‐cannabidiol and the two isomeric (−)‐6a, 10a‐ trans ‐tetrahydrocannabinols. If stronger acids, such as p ‐toluenesulfonic, trifluoroacetic, or hydrochloric acid, are used as mediators for the reaction, (−)‐Δ 8 ‐6a, 10a‐ trans ‐tetrahydrocannabinol is obtained as the main product. Transformation of the thermodynamically more stable Δ 8 ‐tetrahydrocannabinol into the less stable Δ 9 ‐isomer was achieved in a practically quantitative yield by addition of hydrochloric acid and elimination of the elements of hydrochloric acid by means of potassium t ‐amylate. If resorcinols I were used instead of olivetol in the condensation reaction with strong acids, the corresponding homologues of Δ 8 ‐tetrahydrocannabinol were obtained in varying yields.