Two-Step Synthesis of (γ,γ-Difluoroallyl)carbonyl Compounds via Addition of 1,1,2-Trichloro-2,2-difluoroethyl Radical to Silyl Enol Ethers Followed by Reductive Dechlorination

Article abstract of DOI:10.1021/jo00071a027

Ru(II)- or Cu(I)-induced radical reaction of CF2ClCCl2^. radical (2), regioselectively derived from CF2ClCCl3, to trimethylsilyl enol ethers and a ketene silyl acetal yields (β,β,γ-trichloro-γ,γ-difluoropropyl)carbonyl compounds 5 as the intermediates.Spontaneous dehydrochlorination affords <β-chloro-β-(chlorodifluoromethyl)vinyl>carbonyl compounds 4.Reductive dechlorination of 4 with zinc gave γ,γ-difluoroallyl ketones 7a-e and an ester 7f.In some cases, Ni(0)-catalyzed reduction with zinc is superior than the simple hydrodechlorination.