SYNTHESIS OF LABDA-8(17),13(14)-DIENE-15,16-OLIDE AND 15,16-EPOXY-LABDA-8(17),13(16)-14-TRIENE AND THEIR REARRANGEMENT TO CLERODANE DERIVATIVES

Article abstract of DOI:10.1016/0040-4020(82)85106-5

The title compounds 1b and 1c were synthesized from manool.On treatment with either trifluoroacetic acid or formic acid 1b provided in nearly 100percent yield 4a with a rearranged labdane skeleton.With sulfuric acid, however, 1b gave solely Δ^8,9-isomer 5.Reduction of 4a with lithium diisobutylaluminium hydride afforded 4b.On treatment with sulfuric acid 4a reverted to 5.Rearrangement of the epoxide 6 with boron trifluoride-etherate led to a complex product mixture from wich no pure substance was obtained.