Highly Stereoselective Synthesis of γ,δ‐Unsaturated Quaternary α‐Amino Esters via the Tandem N‐Alkylation/Claisen Rearrangement of α‐Imino Allylesters

γ,δ-Unsaturated amino acids are the backbone of various natural products and pharmaceuticals, while quaternary α-amino also powerful enzyme inhibitors, both very important compounds in bioorganic chemistry. A highly efficient synthesis γ,δ-unsaturated esters utilizing tandem umpolung/Claisen rearrangement for α-iminoallyl was developed. This method has a wide range substrates taking account Hammett rule, stereoselective Claisen were achieved by effect DMSO or ortho-substituents imino carbon. Furthermore, product functionalization showed usefulness this reaction detailed mechanism elucidated from isotopic labeling experiments, kinetic isotope effects crossover-experiments.