Sulfonylated N-unsubstituted enamines were synthesized through a chain of chemical and electrochemical transformations via sulfonylation of vinyl azides. The disclosing of the N-unsubstituted enamines synthesis was based on a unique property of the azido group, which is its ability to eliminate the N2 molecule. Furthermore, a formal paradox is observed: a double bond reacts and a double bond is retained. Electrosynthesis proceeded in an undivided cell equipped with a graphite anode and a stainless steel cathode; NH4I was used as a supporting electrolyte.

Oxidative strategies are a powerful tool in organic synthesis for the formation of heteroatom–heteroatom, carbon–heteroatom, and carbon–carbon bonds. Among these processes the reactions of oxidative S–N bond formation deserve considerable interest as convenient, effective, and environmentally friendly alternatives to existing methods for the synthesis of a great variety of organic compounds widely used in organic and medicinal chemistry. These transformations take place through the interaction of S‐ and N‐reagents and an oxidant, by radical or ionic mechanisms. Sulfinic acids and their salts, thiols, sulfonyl hydrazides, and thiosulfonates are generally used as S‐reagents; aliphatic and aromatic amines are usually applied as N‐reagents. The role of the oxidant mostly lies in the oxidation of the S‐reagent, after which the formed active species reacts with the N‐reagent to result in the S–N coupling product. There are two versions of oxidative S–N coupling processes: the intermolecular variant opens simple pathways to sulfen‐, sulfin‐, and sulfonamides, sulfenyl‐ and sulfoximines, sulfanes, and sulfur diimides, whereas the intramolecular one leads to the formation of various heterocycles. Of the major problems associated with successful performance of oxidative S–N coupling reactions, the first relates to the search for coupling partners that will work together to form a new bond under oxidative conditions. The second is the choice of a suitable oxidative system that will not overoxidize starting compounds. That is why mild oxidants, such as hypervalent iodine compounds and copper salts and complexes, are generally applied in these processes. This is the first exhaustive review relating to achievements in oxidative transformations involving S–N bond formation. It summarizes 134 references, mainly from 2000 to 2018, and is divided into chapters according to the classes of compounds synthesized.

Oxidative coupling methodology is widely applied for the formation of carbon-carbon and carbon-heteroatom bonds. This review focuses on methods for oxidative sulfonylation of multiple bonds involving sulfonyl hydrazides, sulfinic acids and their salts as sulfonylation reagents. Under oxidative conditions, they generate sulfonyl radicals, trapped by multiple carbon-carbon bonds resulting in a variety of SO 2-containing products: mainly, vinyl and alkynyl sulfones, hydroxy-, keto, and halo-substituted sulfones, sulfonylated derivatives of carbo-and heterocycles. This exhaustive review summarizes 321 references from 1996 to 2020 with the specialization of the studies of the last five years, and is divided into the chapters according to the classes of compounds being sulfonylated.

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The one-pot sulfonylation/aminoalkylation of styrene derivatives furnishing substituted γ-sulfonylamines was accomplished through a photoredox-catalyzed four-component reaction. Besides one molecule of water and the sodium counterion of the sulfinate, all atoms of the starting materials are transferred to the final product, rendering this process highly atom-efficient. The operationally simple protocol allows for the simultaneous formation of three new single bonds (C–S, C–N, and C–C) and therefore grants rapid access to structurally diverse products.