Sulfur as a bridge: Synthesis of medium rings via a bicyclic sulfonium ion

Abstract

A facile and efficient synthesis of medium rings via a bicyclic sulfonium ion was developed. Spectroscopic evidence for the formation of an intermediate sulfonium moiety is provided. The sulfur atom served as a "bridge" to access the medium ring system and could be removed after use via a Ramberg-Bäcklund process. As a result of the readily available starting materials, simple operation, and mild conditions, these reactions should be an appealing strategy in organic synthesis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.