Ein neuartiger Einstieg in Wittig‐Umlagerungen – Eine stereoselektive [1,2]‐Wittig‐Umlagerung mit Konfigurationsumkehr am Carbanion‐Zentrum

Abstract

A Novel Entry into Wittig Rearrangements – A Stereoselective [1,2]‐Wittig Rearrangement with Inversion of Configuration at the Carbanion CenterThe O,Se‐ketal 10, through lithium naphthalenide induced reductive cleavage of its C–Se bond, was converted into the α‐lithio ether 11a with an equatorially oriented CO bond. At ‐78°C, 11a undergoes a rapid [1,2]‐Wittig rearrangement to provide stereoselectively the homoallylic alcohol 12a with an axial OH group. Thus, the rearrangement proceeds with inversion of configuration at the carbanion center.