Design and Synthesis of a Novel N-(1H-tetrazol-5-yl)methyl Cyclic Peptoid Using Nosyl-protected N-(1-trityl-1H-tetrazol-5-yl)methyl Substituted Glycine

A solid phase synthesis of a cyclic peptoid bearing (1H-tetrazol-5-yl)methyl as N-substituent has been developed employing the monomer approach. The requisite monomeric Nosyl-protected N-(1-trityl-1H-tetrazol-5-yl)methyl substituted glycine was accessed by a convenient synthesis involving Click reaction of Nosyl-protected N-(cyanomethyl)glycine methyl ester and sodium azide as a key step. This building block was then employed in the solid phase synthesis of a tetramer peptoid. The linear tetramer was subjected to macrocyclization using PyBOP to obtain a cyclic peptoid with (1H-tetrazol-5-yl)methyl pendants in good yield.