Wiktelius D, Luthman K. Taking control of P1, P1» and double bond stereochemistry in the synthesis of Phe - Phe (E)-
alkene amide isostere dipeptidomimetics.
The replacement of the Arg3 - Nal4 peptide bond with an (E)-
alkene isostere in compound 7 produced a negative effect on CXCR4 inhibitory activity, probably due to the lack of H - bonding of
amide moiety and a different interaction of pseudo -1,3-allylic strain between the Arg3 carbonyl group and the Nal4 side chain.