N-Chlorosuccinimide-Mediated Oxidative Chlorination of Thiols to Nα -Protected Amino Alkyl Sulfonyl Azides and Their Utility in the Synthesis of Sulfonyl Triazole Acids

An efficient oxidative chlorination of thiols to Nα-protected amino alkyl sulfonyl azides is delineated. The reaction involves in situ generation of sulfonyl chloride employing Nchlorosuccinimide and tetrabutylammonium chloride-water in acetonitrile, followed by the reaction with sodium azide. The protocol is simple, straight forward, mild and high yielding. Amino acids with simple as well as bifunctional side chains were used to obtain Nα-protected amino alkyl sulfonyl azides. Further, sulfonyl azides were utilized to synthesize unnatural amino acids via Cu(OAc)2.H2O/2-amino phenol catalyzed Click reaction with propiolic acid.