An efficient intermolecular trans-selective β-hydroamidation of ynamides to furnish a series of ( Z)-ethene-1,2-diamide derivatives with excellent regio- and stereo-selectivities is described. The trans-β-addition reactions have been illustrated for a wide range of substrates and proceeded under basic reaction conditions using readily available materials in the absence of a transition-metal catalyst. The synthetic approach to these novel ( Z)-ethene-1,2-diamide derivatives paves the way for further exploration of their synthetic application.