2[alpha],3[alpha]:6[alpha],7[alpha]-Diépoxyhimachalane

The stereochemistry of the minor isomer (3,4:9,9a-diepoxy-3,5,5,9-tetramethyldecahydro-1H-benzocycloheptene) resulting from the epoxidation of [beta]-himachalene has been established. The atoms C10 and the gem-dimethyl groups C14 and C15 adopt two positions leading to two conformations for the seven-membered ring: boat-shaped (occupation factor 70%) and chair-shaped (30%). Modelling of these conformations agrees with the statistical distribution in the crystal.

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