[2,3] Wittig Rearrangements of Nonconjugated Secondary α‐Lithioethers: Proof of Stereospecificity and Inversion of the Configuration of the Carbanion C Atom

A stereoselective [2,3] Wittig rearrangement from the racemic α-lithioether syn-1, obtained from tin/lithium exchange in the corresponding α-(tributylstannyl)ether, provides the configuratively uniform homoallyl alcohol anti-2. The α-lithioether diastereomeric to syn-1 rearranges just as stereoselectively to the diastereomer of anti-2. The rearrangements are thus stereospecific and proceed with inversion of configuration on the carbanion carbon atom.