2-(1,3-Dioxan-2-yl)ethylsulfonyl Group:  A New Versatile Protecting and Activating Group for Amine Synthesis

2-(1,3-Dioxan-2-yl)ethylsulfonyl (Dios) chloride was synthesized and used as a new versatile sulfonating agent for amines. Primary and secondary amines were sulfonated very easily in excellent yields with Dios chloride. N-Nonsubstituted and N-monosubstituted Dios-amides, activated amines, were alkylated satisfactorily under new Mitsunobu conditions utilizing (cyanomethylene)tributylphosphorane (CMBP). The Dios group is very stable under basic and reductive conditions and is removed by heating in a hot aqueous solution of trifluoroacetic acid.