Synthesis of Unsaturated Amino Acids by [3,3]‐Sigmatropic Rearrangement of Chelate‐Bridged Glycine Ester Enolates

The highly diastereoselective formation of unsaturated α-amino acids 2 by rearrangement of 1 has now been achieved under mild conditions and in very good yields by using metal enolates. The Ireland variant, which makes use of silylketene acetals, is hereby supplemented and in some cases the yield and selectivity are even improved. Z = benzyloxycarbonyl.