The First Persistent β‐Silyl‐Substituted Vinyl Cation

Abstract

Stabilized by four β-silyl groups through hyperconjugation, 1 is the first vinyl cation without π conjugation to be detected by NMR. The 13C NMR spectrum of 1 at 130o shows separate signals for the two silyl groups on the methine C atom. Ab initio MO calculations on model systems showed that hyperconjugation controls this hindered rotation, resulting in a preference for a conformation with distortion.