Synthesis of a Chloroalkene Dipeptide Isostere-Containing Peptidomimetic and Its Biological Application

The first rapid and efficient chemical synthesis of a cyclic Arg-Gly-Asp (RGD) peptide containing a chloroalkene dipeptide isostere (CADI) is reported. By a developed synthetic method, an <i>N</i>-<i>tert</i>-butylsulfonyl protected CADI was obtained utilizing diastereoselective allylic alkylation as a key reaction. This CADI was also transformed into an <i>N</i>-Fmoc protected CADI in a few steps. The CADI was used in Fmoc-based solid-phase peptide synthesis. The first synthesis of a CADI-containing cyclic RGD peptide was successful, and the synthesized CADI-containing peptidomimetic was found to be a more potent inhibitor against integrin-mediated cell attachment than the parent cyclic peptide