Synthesis of 1-haloethenamides from ynamide through halotrimethylsilane-mediated hydrohalogenation

A convenient synthesis of 1-haloethenamides has been achieved by utilizing halotrimethylsilane (TMSX, X = Cl, Br, I) and water. Halotrimethylsilane in 1 M CH2Cl2 solution functions as a halogen source of the in situ generated HX, and the HX added to the terminal triple bonds of ynamides in Markovnikov fashion.

Simple synthesis of 1-haloethenamides was successfully achieved through the addition of in situ generated HX.