Ethynyloxirane anions: a new tool for natural product synthesis

Ethynyl oxiranes can be deprotonated with nBuLi in THF and trapped with various electrophiles, providing a stereoselective access to trisubstituted oxiranes. Alkyl iodides and aldehydes react readily with the ethynyloxiranyl anions but not sulfonyl derivatives. Mechanistic investigations highlighted the stabilizing role of the ethynyl group, the localization of the anion and the coordinating role of the oxirane oxygen atom during deprotonation.