Iron(III)-Mediated Oxy-Sulfonylation of Enamides with Sodium and Lithium Sulfinates

An iron-mediated vicinal difunctionalization of enamides and enecarbamates with sulfinic acid salts and alcohols is described. This reaction proceeds under mild conditions and furnishes the oxy-sulfonylated products in moderate to excellent yields. Moreover, the direct incorporation of sulfur dioxide into the sulfonylated products via organolithium chemistry has been achieved. The formed N - O -acetals are competent acylimine precursors. Their utilization as building block for the synthesis of biologically relevant β-amidosulfones is described as well.