Ac-Phe-Tyr-phosphoSer-Ψ[CH═C]-Pro-Arg-NH
2
AND Fmoc-bis(pivaloylmethoxy)phosphoSer-Ψ[CH═C]-Pro-2-aminoethyl-(3-indole); and their Phospho-(D)-serine stereoisomers are novel compounds. Ψ refers to a pseudo amide. Such novel compounds advantageously may be used as alkene mimics.