The Aluminum Alkoxide Rearrangement of Epoxides, Part I: The Synthesis of Allylic Alcohols and Glycols Monoethers
1968; Wiley; Volume: 6; Issue: 5 Linguagem: Inglês
10.1002/ijch.196800089
ISSN1869-5868
Autores Tópico(s)Synthesis and Catalytic Reactions
ResumoAbstract The rearrangement of epoxides catalyzed by aluminum alkoxides affords a selective way of preparing allylic alcohols in high yields. It takes place in the presence of catalytic amounts of aluminum isopropoxide (AIP) which leads to cleavage of the ether linkage at the site of the more substituted α‐carbon of the oxirane. A mechanism with a six membered transition state involving a concerted proton transfer from the least substituted carbon in β position of the oxirane oxygen is suggested. Mild conditions are sufficient to promote this rearrangement to allylic alcohols with epoxides having a tertiary carbon in α‐position of the oxirane oxygen. However, alkoxide transfer to the cleaved α‐carbon may take place when primary or secondary carbons are the only ones present in the α‐positions of the oxirane oxygen with more drastic conditions and equimolar amounts of AIP. The major product is a mixture of α‐glycol monoethers.
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