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.