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 NO -acetals are competent acylimine precursors. Their utilization as building block for the synthesis of biologically relevant β-amidosulfones is described as well. Introduction: Molecules bearing sulfonyl-derived functional groups, such as sulfones or sulfonamides, play an important role in organic chemistry and are widely used in various fields. 1,2 Among the different classes of sulfonyl-derived functional groups, sulfones are of particular interest. They display intriguing chemical and physical properties as well as interesting biological activities. Sulfones, which are often considered as chemical chameleons 3 , are versatile building blocks in organic synthesis. The sulfone motif can be found in various molecules with different applications ranging from agrochemcials and functional materials to active pharmaceutical ingredients. 2-4 Traditional approaches for the construction of sulfones include Friedel-Crafts type reactions of arenes with sulfonyl chlorides 5 , the oxidation of sulfides and sulfoxides 6 , addition reactions of sulfonyl radicals to alkenes and alkynes 7 or the electrophilic trapping of sulfinic acid salts 8,9. In the last ten years novel approaches based on the direct incorporation of sulfur dioxide 10, 11 or the functionalization of C-H bonds 12,13 have emerged as attractive and more sustainable alternatives.
A stereoselective synthesis of isoindolo[2,1-a]quinolin-11(5H)ones containing three contiguous stereogenic centers is described. This Lewis-acid mediated reaction of enamides with N-aryl-acylimines affords the desired fused heterocyclic isoindo-linones in high yields and diastereoselectivities. Scope and limitations of this method are discussed. The stereochemical outcome of this transformation indicates a stepwise reaction pathway.
<p>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 <i>N</i>-<i>O</i>-acetals are competent acylimine precursors. Their utilization as building block for the synthesis of biologically relevant β-amidosulfones is described as well. <br></p>
<p>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 <i>N</i>-<i>O</i>-acetals are competent acylimine precursors. Their utilization as building block for the synthesis of biologically relevant β-amidosulfones is described as well. <br></p>
A stereoselective synthesis of isoindolo[2,1-a]quinolin-11(5H)-ones containing three contiguous stereogenic centers is described. This Lewis-acid mediated reaction of enamides with N-aryl- affords the desired fused heterocyclic isoindolinones in high yields and diastereoselectivities. Scope and limitations of this method are discussed. The stereochemical outcome of this transformation indicates a stepwise reaction pathway.
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