Haschisch‐Inhaltsstoffe. 7. Mitteilung. Synthese von (−)‐11‐Hydroxy‐Δ8‐6a, 10a‐trans‐Tetrahydrocannabinol

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Abstract
When (−)‐Δ8‐6a, 10a‐trans‐THC (THC = Tetrahydrocannabinol), in the form of its diacetate, was irradiated in the presence of oxygen and a sensitizer, followed by reduction with NaBH4, three allylic alcohols were formed: (−)‐8α‐and (−)‐8β‐hydroxy‐Δ9,11‐THC (proportion 3:1) and (−)‐9α‐hydroxy‐Δ7,8‐THC. Acetylation of the epimeric 8‐hydroxy‐compounds with Ac2O/pyridine gave the corresponding diacetates.When (−)‐Δ8‐6a, 10a‐trans‐THC, in the form of its tetrahydropyranyl derivative, was heated with m‐chloroperbenzoic acid, the two epimeric 8,9‐epoxides were formed in equal amounts. These compounds, on treatment with butyllithium, afforded (−)‐8α‐ and (−)‐8β‐hydroxy‐Δ9,11‐ 6a, 10a‐trans‐THC‐tetrahydropyranylether. After removing the protecting group and treatment with Ac2O/pyridine the same diacetates, as formed by photooxygenation of (−)‐Δ8‐THC‐acetate, were obtained as a 1:1‐mixture.On heating these epimeric diacetates to 290° they underwent allylic rearrangement to (−)‐11‐acetoxy‐Δ8‐THC‐acetate. From this (−)‐11‐hydroxy‐Δ8‐6a, 10a‐trans‐THC was obtained by treatment with LiAlH4.