2 3 sigmatropic rearrangement

Sommelet-Hauser rearrangement is one of the thermal [2,3]-sigmatropic rearrangements,  in which the benzylic quaternary ammonium salts are treated within the presence of a strong base like  NaNH2, KNH2, as well as alkyl lithium to prepare the Substituted 3° benzylic amine.