Novel synthesis of a Phe-Gly E-alkene dipeptide isostere

Article abstract of DOI:10.1016/0040-4039(96)01108-2

A new strategy for the synthesis of Boc-Pheψ(E-CH=CH)Gly-OH (11) is described. The double bond is generated employing a β elimination of the mesyloxy group of 6. This elimination proves to be the key step within the synthesis. Different products are obtained dependent on the base as well as on the reaction conditions. Employing KOtBu leads to E-(5S)-(t-Butyloxycarbonylamino)-6-phenyl-1,3-hexadiene 7 whereas NaOMe causes a γ elimination resulting the aziridine 9. Diene 7 is converted into the corresponding Pheψ(E-CH=CH)Gly isostere by subsequent hydroboration and Jones oxidation.