Reactivity of ynamides with AlCl 3 and ICl: Ready access to ( E )-α-chloroenamides and ( E/Z )-α-chloro-β-iodo-enamides

AlCl3 acts as a chlorinating agent for ynamides in the presence of stoichiometric amount of water in the environmentally benign solvent dimethylcarbonate, affording efficient access to (E)-α-chloroenamides via hydrochlorination, with water as a protic source. The role of water in the reaction was proven by deuterium labelling experiment. Epoxy-ynamides undergo iodochlorination in addition to the cleavage of the epoxy ring to afford (E/Z)-α-chloro-β-iodo-enamides. Regio- and stereochemical assignments for the products are based on X-ray crystallographic studies. Chloroenamides are formed regio- and stereo-specifically via hydrochlorination of ynamides with AlCl3+H2O (1:1) in a dimethyl carbonate; aryl substituted epoxy ynamides afford (iodo)(chloro) enamides upon treatment with ICl.