Ligand exchange reaction of sulfoxides in organic synthesis: A versatile procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides

A novel two-step procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides is described. Methylesters are reacted with lithium carbanion of chloromethyl phenyl sulfoxide to give α-chloro α-sulfinyl ketones in 70 to 90% yields. Potassium enolate of the α-chloro α-sulfinyl ketone was treated with tert-butyllithium at −78 °C to give alkynolate via alkylidene carbenoid. This intermediate was treated with alcohols, thioles, 5% aqueous NaOH, and amine hydrochlorides to afford one-carbon homologated esters, thioesters, carboxylic acids and amides, respectively, in good to excellent yields.