Cyclopropyl building blocks in organic synthesis. Part 81: Striving for unusually strained oxiranes: epoxidation of spirocyclopropanated methylenecyclopropanes
作者:Daniel Frank、Sergei I Kozhushkov、Thomas Labahn、Armin de Meijere
DOI:10.1016/s0040-4020(02)00695-6
日期:2002.8
1-Oxa[3]triangulane 13, the epoxide of methylenespiropentane, is thermally stable up to 300°C, but immediately rearranges to spiro[2.3]hexan-4-one (7) in the presence of lithium iodide at ambient temperature. The permethylated bicyclopropylidene 10 is simply less reactive than the parent bicyclopropylidene (6a) towards dimethyldioxirane, but yields the isolable epoxide 11 (94%) with mCPBA. In contrast