3-NITRO-2-PYRIDINESULFENYL CHLORIDE

3-Nitro-2-pyridinesulfenyl chloride (NpysCl) was employed as the starting material for the synthesis of N-, O- and S-Npys-protected amino acid.

The 3-nitro-2-pyridinesulphenyl (Npys) moiety is useful as a protecting-activating group for cysteine, particularly in the synthesis of cyclic and unsymmetrical disulfides. The stability of NpysCl was studied in various solvents.

The chloride crystallises as yellow needles from CH2Cl2. When pure, it is stable for several weeks at room temperature, and no decomposition was observed after 6 months at <0o. It is moisture sensitive. UV (MeCN) has at 231nm max ( 12,988), 264nm ( 5,784) and 372nm ( 3,117). [NMR and UV: Matsuda & Aiba Chem Lett 951 1978, Wagner et al. Chem Ber 75 935 1942.]