1981 年 29 巻 9 号 p. 2548-2556
Four 1, 2, 2-trimethylcyclopentane derivatives, (+)-(1S, 3S)-3-acetoxymethyl-1, 2, 2-trimethyl-1-vinylcyclopentane (3), (+)-(1S, 3S)-3-acetoxymethyl-1-(3'-hydroxypropenyl)-1, 2, 2-trimethylcyclopentane (4), (+)-(1R, 3S, 1'S)-3-acetoxymethyl-1-(1', 2'-epoxyethyl)-1, 2, 2-trimethylcyclopentane (5), and (+)-(1R, 3S, 1'R)-3-acetoxymethyl-1-(1', 2'-epoxyethyl)-1, 2, 2-trimethylcyclopentane (6), which were synthesized from d-camphor (1), were subjected to acid treatment. It was found that i) treatment of 3 with 2, 4, 4, 6-tetrabromocyclohexa-2, 5-dienone yielded a cyclohexane derivative (7) which was formed via a ringenlargement reaction sequence, ii) BF3-etherate treatment of 5 furnished three cyclopentane derivatives (14, 15, 16), among which 14 and 15 possess a 2-oxa-bicyclo [3.3.0]-octane skeleton produced through successive migrations of methyl groups, and iii) BF3-etherate or titanium tetrachloride treatment of 6 resulted in a ring-enlargement reaction giving 19 and 20, or 21.
