Ionic liquid [Hmim]HSO4-promoted one-pot oxidative conjugate addition of sulfur-centred nucleophiles to Baylis-Hillman adducts

The first example of the one-pot oxidative conjugate addition of sulfur-centred nucleophiles to Baylis-Hillman adducts is reported. The reaction involves oxidation of Baylis-Hillman adducts with NaNO₃ in the Brønsted acidic ionic liquid Hmim]HSO₄ to give E]-α-cyanocinnamaldehydes followed by conjugate hydrothiocyanation/hydrosulfenylation with NH₄SCN/PhSH to afford the corresponding β-thiocyanato (or β-phenylsulfenyl)-α-cyanohydrocinnamaldehydes diastereoselectively in 76-89% yields in a one-pot procedure. After isolation of the product, the ionic liquid Hmim]HSO₄ could be easily recycled for further use.