Advances in photochemical and electrochemical incorporation of sulfur dioxide for the synthesis of value-added compounds.

Organic photochemistry and electrochemistry currently receive tremendous attention in organic synthesis as both techniques enable the reagent-less activation of organic molecules without using expensive and hazardous redox reagents. The incorporation of SO2 into organic molecules is a relatively modern research topic, which likewise gains immense popularity since the discovery of the SO2 surrogate DABSO. Sulfur-containing organic molecules are omnipresent in pharmaceuticals and agrochemicals. This review covers the recent progress in electrochemical and photochemical methodologies for the incorporation and uses of SO2 in the synthesis of value-added compounds. Additionally, different work t…

Electrochemical nitration with nitrite

Aromatic nitration has tremendous importance in organic chemistry as nitroaromatic compounds serve as versatile building blocks. This study represents the electrochemical aromatic nitration with NBu4 NO2 , which serves a dual role as supporting electrolyte and as a safe, readily available, and easy-to-handle nitro source. Stoichiometric amounts of 1,1,1-3,3,3-hexafluoroisopropan-2-ol (HFIP) in MeCN significantly increase the yield by solvent control. The reaction mechanism is based on electrochemical oxidation of nitrite to NO2 , which initiates the nitration reaction in a divided electrolysis cell with inexpensive graphite electrodes. Overall, the reaction is demonstrated for 20 examples w…

Metallfreie, elektrochemische Synthese von Sulfonamiden direkt aus (Hetero)arenen, SO 2 und Aminen

Metal- and Reagent-Free Electrochemical Synthesis of Alkyl Arylsulfonates in a Multi-Component Reaction.

Abstract This work presents the first electrochemical preparation of alkyl arylsulfonates by direct anodic oxidation of electron‐rich arenes. The reaction mechanism features a multi‐component reaction consisting of electron‐rich arenes, an alcohol of choice and excess SO2 in an acetonitrile‐HFIP reaction mixture. In‐situ formed monoalkyl sulfites are considered as key intermediates with bifunctional purpose. Firstly, this species functions as nucleophile and secondly, excellent conductivity is provided. Several primary and secondary alcohols and electron‐rich arenes are implemented in this reaction to form the alkyl arylsulfonates in yields up to 73 % with exquisite selectivity. Boron‐doped…

Frontispiece: Metal‐Free Electrochemical Synthesis of Sulfonamides Directly from (Hetero)arenes, SO 2 , and Amines

Cover Feature: Metal‐ and Reagent‐Free Electrochemical Synthesis of Alkyl Arylsulfonates in a Multi‐Component Reaction (Chem. Eur. J. 38/2020)

Metal‐Free Electrochemical Synthesis of Sulfonamides Directly from (Hetero)arenes, SO2, and Amines

Abstract Sulfonamides are among the most important chemical motifs in pharmaceuticals and agrochemicals. However, there is no methodology to directly introduce the sulfonamide group to a non‐prefunctionalized aromatic compound. Herein, we present the first dehydrogenative electrochemical sulfonamide synthesis protocol by exploiting the inherent reactivity of (hetero)arenes in a highly convergent reaction with SO2 and amines via amidosulfinate intermediate. The amidosulfinate serves a dual role as reactant and supporting electrolyte. Direct anodic oxidation of the aromatic compound triggers the reaction, followed by nucleophilic attack of the amidosulfinate. Boron‐doped diamond (BDD) electro…

Electrochemical synthesis of sulfamides.

Herein we demonstrate the first electrochemical synthesis protocol of symmetrical sulfamides directly from anilines and SO2 mediated by iodide. Sulfamides are an emerging functional group in drug design. Highlights are the direct use of SO2 from a stock solution and no necessity of any supporting electrolyte. Overall, the reaction has been demonstrated for 15 examples with yields up to 93%.

Frontispiz: Metallfreie, elektrochemische Synthese von Sulfonamiden direkt aus (Hetero)arenen, SO 2 und Aminen

CCDC 2070594: Experimental Crystal Structure Determination

Related Article: Stephan P. Blum, Lukas Schäffer, Dieter Schollmeyer, Siegfried R. Waldvogel|2021|Chem.Commun.|57|4775|doi:10.1039/D1CC01428E

CCDC 2032478: Experimental Crystal Structure Determination

Related Article: Stephan P. Blum, Tarik Karakaya, Dieter Schollmeyer, Artis Klapars, Siegfried R. Waldvogel|2021|Angew.Chem.,Int.Ed.|60|5056|doi:10.1002/anie.202016164

CCDC 1988057: Experimental Crystal Structure Determination

Related Article: Stephan P. Blum, Dieter Schollmeyer, Maris Turks, Siegfried R. Waldvogel|2020|Chem.-Eur.J.|26|8358|doi:10.1002/chem.202001180