Iron(III)-Mediated Oxysulfonylation 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 oxysulfonylated 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 blocks for the synthesis of biologically relevant β-amidosulfones
is described as well.