Gold-Catalyzed Intermolecular Formal [4 + 2 + 2]-Cycloaddition of Anthranils with Allenamides

Org Lett. 2020 Aug 7;22(15):5990-5994. doi: 10.1021/acs.orglett.0c02083. Epub 2020 Jul 17.

Abstract

The construction of eight-membered rings is a challenging issue due to unfavorable transannular strain and entropic barriers. We report herein a gold-catalyzed formal [4 + 2 + 2] cycloaddition reaction of anthranils with allenamides to deliver oxa-bridged eight-membered heterocycles in accepted yields with unique E/Z configuration. Moreover, the asymmetric [4 + 2 + 2] cycloaddition by using chiral phosphoramidite gold catalyst has also been conducted.