Metal-Free Amidation Reactions of Terminal Alkynes with Benzenesulfonamide.

A novel and efficient approach has been developed to synthesize α-sulfonylamino ketones through the reaction between terminal alkynes and sulfonamides under ambient air using PIDA (diacetoxy iodobenzene). A library of α-sulfonylamino ketone derivatives having a variety of substituents has been synthesized. A plausible reaction pathway has been predicted. This reaction offers a broad substrate scope, metal-free synthesis, excellent regioselectivity, easily accessible reactants, and room temperature reaction conditions under ambient air and is operationally simple. A gram-scale synthesis demonstrates the potential applications of the present method. In addition, we have also synthesized α-acetoxy ketones in the case of absence of sulfonamide.