NOVEL SYNTHESIS OF A PHE-GLY E-ALKENE DIPEPTIDE ISOSTERE

A new strategy for the synthesis of Boc-Phe psi(E-CH=CH)Gly-OH(11) is described. The double bond is generated employing a beta elimination o f 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 )-(t-Butyloxycarbonylamino)-6-phenyl-1,3-hexadiene 7 whereas NaOMe cau ses a gamma elimination resulting the aziridine 9. Diene 7 is converte d into the corresponding Phe psi(E-CH=CH)Gly isostere by subsequent hy droboration and Jones oxidation. Copyright (C) 1996 Elsevier Science L td