Convergent synthesis of potent peptide inhibitors of the Grb2-SH2 domain by palladium catalyzed coupling of a terminal alkyne

A new strategy was developed to prepare in a very efficient and convergent manner C-terminal modified tripeptides with high affinities for the Grb2-SH2 domain. Using Pd(PPh3)2Cl2 as catalyst, selected naphthyl iodides and triflates were coupled to Ac-Pmp(t-Bu)2-Ac6c-Asn-NH(prop-2-ynyl). The resulting alkyne derivatives were hydrogenated and deprotected to afford potent Grb2-SH2 inhibitors.