Templated assembly of chiral medium-sized cyclic ethers via 8-endo-trig nucleophilic cyclization of cyclopropenes

Abstract

An efficient approach toward enantioenriched eight-membered heterocycles via the intramolecular formal substitution of bromocyclopropanes with oxygen-based nucleophiles has been developed. The reaction proceeds via a reactive cyclopropene intermediate, which undergoes a rapid 8-endo-trig cyclization affording cis-fused [6.1.0] bicyclic products exclusively. The quaternary chiral center in the cyclopropene governs the configuration of the other two stereocenters in the final product