Abstract
Alkyl aryl ketones on treatment with SiCl4/urea–hydrogen peroxide (UHP) or SiCl4/iodosylbenzne reagent systems afforded α-chloroketones in excllent yields, while ketones with higher enol content provide exclusively α,α-dichloroketones under exceedingly mild conditions. The reaction proceeds via the initial formation of silyl enol ethers. A polarized chlorine intermediate that resulted from the coordination of SiCl4 with the in situ formed trichlorosilyl hypochlorite Cl3SiOCl is thought to be the active chlorinating agent.
Notes
a Yields and reaction time using TCS/UHP.
b Yields and reaction time using TCS/PhIO.