Synthetic Strategies to a Backbone-Side Chain Cyclic SHP-1 N-SH2 Ligand Containing N-Functionalized Alkyl Phosphotyrosine

The cyclic peptide EGLNcΨ[CON((CH2)3NH)pYNleE(NHCH2CO)]L-NH2 (1) was designed and synthesized according to a native interaction partner of tyrosine phosphatase SHP-1. We introduced N-aminopropyl-phosphotyrosine to enable backbone-side chain cyclization with a glutamic acid derivative as counterpart for cyclization. Different approaches have been compared to find a strategy for the generation of backbone and backbone-side chain cyclic phosphopeptides.