Wittig-type Reaction of Dimetallated Carbodianion Species as Produced by Zinc Reduction of gem-Polyhalogen Compounds in the Presence of Levis Acids

Article abstract of DOI:10.1246/bcsj.53.1698

Treatment of R¹COR² with a suspension prepared from diiodomethane, trimethylaluminium and excess zinc in tetrahydrofuran at room temperature affords olefins R¹R²C=CH2 in fair (R¹,R²=alkyl) to good (R¹=alkyl, R²=H) yields.The ketone methylenation is better carried with another system consisting of CH2Br2-Zn-TiCl4.Ketones and aldehydes are transformed into α-chloro α,β-unsaturated esters or α,β-unsaturated esters in good yields on treatment with methyl trichloroacetate or t-butyl dichloroacetate (ethyl dibromoacetate) in the presence of diethylaluminium chloride and zinc.