Studies of chrysanthemic acid derivatives: Catalysed reactions of 3-(2-hydroxymethyl-3,3-dimethylcyclopropyl)-2-methylpropanol and formation of a novel eight-membered cyclic sulphite

Acid catalysed reaction of the cyclopropanediol (3) derived from cis-chrysanthemic acid cis-(1) afforded, depending on the reaction conditions, 3-vinyl-2,2,5,5-tetramethyltetrahydrofuran (4) and 4,4,7,7-tetramethyl-3- oxabicyclo[4.1.0]heptane (5). On treatment with thionyl chloride-pyridine complex there was obtained in addition the eight-membered cyclic sulphite, 6,6,9,9-tetramethyl-3,5-dioxa-4-thiabicyclo[6.1.0]nonane 4-oxide (6). X-Ray analysis confirms a boat-chair conformation with the S=O group trans to the cyclopropane ring and in an equatorial situation. Thermal reaction of (6) gave either (4) or a mixture of (5), cis-chrysanthemol (7), and cis-isochrysanthemol (8).