Controlled Ring Opening of N-Sulfinyl- and N-Silyl-N-carboxyanhydrides (NCA): One-Pot Synthesis
of Dipeptides and Unsymmetrical Peptidyl Ureas from Unprotected
NCA
Controlled Ring Opening of <i>N</i>-Sulfinyl- and <i>N</i>-Silyl-<i>N</i>-carboxyanhydrides (NCA): One-Pot Synthesis
of Dipeptides and Unsymmetrical Peptidyl Ureas from Unprotected
NCA
We report herein new labile protecting groups of N-carboxyanhydrides (NCA) useful to prevent polymerization during coupling reactions with nitrogen nucleophiles. Thus, N-sulfinyl-NCA 1 and N-silyl-NCA 2 were prepared in situ and involved, without being isolated, in coupling reactions with various α-amino esters to furnish dipeptides 3 and unsymmetrical peptidyl ureas 4, respectively, in good yields.