Alcoholysis of epoxidized polyisoprenes by direct opening of oxirane rings with alcohol derivatives 1. Modelization of the reaction

Alcoholysis of 4,5-epoxy-4-methyloctane selected as a model molecule of epoxidized 1,4-polyisoprene was achieved with various alcohols using cerium ammonium nitrate as catalyst. Next to the expected alkoxy alcohol, side products resulting from oxirane rearrangement were identified: 5-methyloctan-4-one, 5-methyloct-5-en-4-ol and 2-n-propyl-hexen-3-ol. One of them, 5-methyloct-3-en-4-ol. was demonstrated to be able to react with alcohols so leading to the formation of allylic ethers. From the diastereoisomer distribution, as well as the effect of temperature and solvent on the reaction, a coordinative S(N)2 mechanism able to explain the formation of the various products identified, is suggested. (C) 2001 Elsevier Science Ltd. All rights reserved.