Re‐Arrangement silicissimo ! Vinylcyclopropanes (VCPs) undergo a formal (5+1) cycloaddition when reacted with in situ generated silylium ions. The bond reorganization is connected to an aryl migration to eventually yield a silacyclohexane derivative which is regioisomeric to the expected product. Reaction mechanisms that rationalize the formation of the major and minor products are presented based on a series of control experiments and quantum‐chemical calculations.
A transition‐metal‐free (5+1) cycloaddition of aryl‐substituted vinylcyclopropanes (VCPs) and hydrosilanes to afford silacyclohexanes is reported. Catalytic amounts of the trityl cation initiate the reaction by hydride abstraction from the hydrosilane, and further progress of the reaction is maintained by self‐regeneration of the silylium ions. The new reaction involves a [1,2] migration of an aryl group, eventually furnishing 4‐ rather than 3‐aryl‐substituted silacyclohexane derivatives as major products. Various control experiments and quantum‐chemical calculations support a mechanistic picture where a silylium ion intramolecularly stabilized by a cyclopropane ring can either undergo a kinetically favored concerted [1,2] aryl migration/ring expansion or engage in a cyclopropane‐to‐cyclopropane rearrangement.
Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Tao He, Guoqiang Wang, Vittorio Bonetti, Hendrik F. T. Klare, Martin Oestreich