A novel strategy toward [6,5]-bicyclic β-turn dipeptide

A novel strategy toward the syntheses of [6,5]-bicyclic β-turn dipeptides has been developed starting from δ,ε-unsaturated amino acids. This is the first example showing that this scaffold can be synthesized from a terminal alkene using a trifluoroacetyl protected amino acid. Both enantiomers of the δ,ε-unsaturated amino acid were synthesized by a modified method using Ni(II)-complexes.