Asymmetric Sequential Corey-Chaykovsky Cyclopropanation/Cloke-Wilson Rearrangement for the Synthesis of 2,3-Dihydrofurans

Org Lett. 2021 Nov 19;23(22):8755-8760. doi: 10.1021/acs.orglett.1c03225. Epub 2021 Nov 4.

Abstract

The first sequential Corey-Chaykovsky cyclopropanation/Cloke-Wilson rearrangement between propargyl sulfonium salts and acrylonitrile derivatives has been developed, affording the tetra-substituted 2,3-dihydrofurans in generally excellent yields (57-98%) with good diastereoselectivities (7:1-18:1). In addition, chiral propargyl sulfonium salt is also suitable for this strategy, giving the optically active 2,3-dihydrofurans with good enantioselectivities. This reaction sequence was designed upon in situ generated 10π-conjugated structures from the dearomatization of indole fragments and subsequent intramolecular 1,6-addition.