Regio- and Stereoselective Hydrosulfonation of Alkynylcarbonyl Compounds with Sulfinic Acid in Water.

We report the atom-economic and environmentally friendly synthesis of Z-β-sulfonyl-a,β-unsaturated carbonyl compounds in water. The mechanism study reveals that the hydrosulfonylation of alkynylcarbonyl compounds with sulfinic acids proceeds via a mechanism that features a sulfinic acid molecule protonating an alkynyl motif to form the ethenium intermediate, which subsequently reacted with a sulfonyl anion to afford the desired products. The ethenium intermediate differentiated electronic and steric demands between the two substituents on the C≡C triple bond of the alkyne substrates to exhibit high regio- and stereoselectivity from a wide range of Z-β-sulfonyl-a,β-unsaturated carbonyl compounds.