Iron-Catalyzed Synthesis of ß-Chlorovinyl and a,ß-Alkynyl Ketones from Terminal and Silylated Alkynes with Acid Chlorides

A simple efficient method for the iron(III)-catalyzed synthesis of substituted beta-chlorovinyl ketones and a,beta-alkynyl ketones from terminal and silyl-substituted alkynes with acid chlorides, respectively, is described. This method features easily available starting materials, a cheap and non-toxic catalyst, simple manipulation and mild reaction conditions. Evidence shows that the catalytic addition of the acid chloride to a terminal alkyne to give (Z)-beta-chlorovinyl ketones favours a concerted pathway via a four-membered ring transition state between the two alkyne carbons and the carbon-chloride bond of the acid chloride.