Terpenoids. IX. Permanganate Oxidation of Thujopsene. 2. Neutral Products

Article abstract of DOI:10.1246/bcsj.60.4175

Permanganate oxidation of thujopsene 1 in dry and aqueous acetone was reexamined with a careful separation of the neutral part of the products.In dry acetone, the major products were Δ⁹-thujopsen-8β- and 8α-ols (2 and 3) which easily decomposed to thujopsadiene 6.In aqueous acetone, 1 gave 8β-hydroxythujopsan-9-one 8 and thujopsane-8α,9α-diol 11 as main products, besides 8β,9β-diol 10, 8α-hydroxythujopsan-9-one 9, and epimeric allyl alcohols 2 and 3.The hydroxy ketone 8 was isomerized to a ring contracted compound, 4α-acetyl-4β-hydroxy-6α,10,10-trimethyltricyclo<4.4.0.0^1,3>decane 4 during alumina chromatography. 8β,9-Epoxy-10-thujopsanone 5 was isolated as a minor product.Kawamura's glycol was an eutectic mixture of 10 and 11.