1-Haloalkyl Aryl Sulfoxides as Useful Agents in Synthesis of α-Halo Ketones: A New Synthesis of α-Halo Ketones, α-Halo α,β-Unsaturated Ketones, and α-Halo Cross Dienones from Aldehydes

Abstract

Abstract α-Halo α-sulfinyl ketones were synthesized in two steps from 1-haloalkyl aryl sulfoxides and aldehydes in high yields. Desulfinylation of the α-halo α-sulfinyl ketones was performed with ethylmagnesium bromide in ether at low temperature to afford α-halo ketones via magnesium enolates in high yields. The magnesium enolate intermediates were trapped with various electrophiles such as deuterium oxide, ethyl chloroformate, and chlorotrimethylsilane. Trapping of the magnesium enolate intermediate with carbonyl compounds afforded a new type of the directed aldol reaction. Desulfinylation of the sulfinyl group of the α-halo α-sulfinyl ketones under thermal conditions gave α-halo α,β-unsaturated ketones or α-halo cross dienones.