Asymmetric [1,2]-sigmatropic rearrangement of benzylic ammonium ylids

Our group has previously reported the asymmetric [2,3]-sigmatropic rearrangement of allylic ammonium ylids and its application towards the synthesis of aminoacids such as allylglycine. We now wish to report an efficient synthesis of phenylalanine derivatives via the asymmetric [1,2]-sigmatropic rearrangement of benzylic ammonium ylids. Asymmetry was introduced by using a range of chiral auxiliaries: their effect on the reaction yield and diastereoselectivity will be discussed.