Facial synthesis of sulfinic esters via copper-catalyzed reaction of sulfonyl hydrazides with alcohols in air

The efficient Cu-catalyzed esterification of sulfonyl hydrazides with alcohols in air is described, providing sulfinic esters in good yields and broad scope. Mechanistic studies suggest that the reaction likely proceeds through free-radical formation including arylthio radical and arylsulfonyl radical, while arylsulfuric acid are the major esterification intermediate in this transformation.     

Recent advances in C–S bond construction to synthesize sulfone

Sulfone is prevalent in natural products and has been widely used in organic chemistry. Among the approaches of installing sulfonyl group, sulfonylation starting from stable and environmentally friendly sulfonyl sources is promising and attractive. Diverse mild sulfonyl sources such as DABSO, inorganic metal salts, sulfinic acids/salts, and sulfonyl hydrazides have been applied to construct sulfone. In this review, recent advances for the sulfonylation under transition metal catalysis and metal-free conditions are summarized.     

MnO2‐Promoted Oxidative Radical Sulfonylation of Haloalkynes with Sulfonyl Hydrazides: C(sp)–S Bond Formation towards Alkynyl Sulfones

A catalyst‐free oxidative radical sulfonylation of haloalkynes with sulfonyl hydrazides is reported. It represents an example of C(sp)−S bond formation using sulfonyl hydrazides as sulfonyl radical sources. Various alkynyl sulfones were synthesized in moderate to good yields. Having MnO₂ as the oxidant is very critical for this transformation. Remarkably, the self‐coupling reaction of haloalkynes through C(sp)−C(sp) bond formation is significantly inhibited under the standard reaction conditions.     

An Efficient Synthesis of Sulfonylhydrazides and Sulfonylsemicarbazides by Utilizing Alumina as a Catalyst

Sulfonyl hydrazides and sulfonyl semicarbazides are readily prepared by the reacting of hydrazine derivatives with sulfonyl chlorides in the presence of basic alumina under solvent‐free conditions. Reaction of a sulfonyl chloride with t‐butylcarbazate, followed by hydrolysis provides the corresponding sulfonyl hydrazides in higher yield and shorter time than previously reported.     

Cu-catalyzed aerobic oxidative synthesis of sulfonamides from sulfonyl hydrazides and amines

An environmentally friendly route for sulfonamides has been developed. The oxidative coupling of sulfonyl hydrazides and amines was catalyzed by CuBr₂ to produce various sulfonamides with the water and nitrogen gas as byproducts. Preliminary experiments revealed that the sulfonyl radical is likely to be involved in the reaction mechanism.     

H4SiW12O40-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides: An efficient synthesis of 3,4-disubstituted 1H-pyrazoles

A simple and efficient method for the synthesis of pyrazoles through a silicotungstic acid(H₄Si W₁₂O₄₀)-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides has been developed. Various epoxides/aldehydes were smoothly reacted with sulfonyl hydrazides to furnish regioselectivity 3,4-disubstituted 1H-pyrazoles. The application of such an earth-abundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of 3,4-di...     

Metal-free sulfonylation of quinones with sulfonyl hydrazides in water: Facile access to mono-sulfonylated hydroquinones

This paper describes a simple and practical protocol for the direct synthesis of monosulfonylated hydroquinones through a transition-metal-free cross-coupling between quinones and sulfonyl hydrazides in water. The procedure tolerates a variety of quinones and widely available sulfonyl hydrazides.     

Sulfonyl hydrazides as sulfonyl sources in organic synthesis

While sulfonyl hydrazides are widely utilized in organic synthesis, it is only in recent years that they have emerged as powerful sulfonyl sources. The hydrazinyl group can be readily removed from sulfonyl hydrazides under thermal, basic, oxidative, radical, and/or transition metal-catalyzed conditions, and subsequently, the remaining sulfonyl groups are able to form carbon-sulfur, sulfur-nitrogen, sulfur-halogen, sulfur-sulfur, and sulfur-selenium bonds with a wide variety of organic compounds, providing alternative approaches to the preparation of sulfones, sulfonamides, sulfonyl halides, thiosulfonates, and selenosulfonates. Moreover, some of the carbon-sulfur bond-forming reactions have been successfully applied to the construction of carbocycles, heterocycles, and stereogenic centers.     

BCl3‐Mediated Ene Reaction of Sulfur Dioxide and Unfunctionalized Alkenes

The first ene reactions of SO₂ and unfunctionalized alkenes are reported. Calculations suggest that the endergonic ene reactions of SO₂ with alkenes can be used to generate β,γ‐unsaturated sulfinyl and sulfonyl compounds. Indeed, in the presence of one equivalent of BCl₃, the unstable sulfinic acid form stable sulfinic acid?BCl₃ complexes that can be reacted in situ with NCS to generate corresponding sulfonyl chlorides, or with a base to generate corresponding sulfinates. The latter can be reacted with electrophiles to generate sulfones, or with silyl chloride to form β,γ‐unsaturated silyl sulfinates. The sulfinic acid?BCl₃ complexes can be reacted with ethers that act as oxygen nucleophiles to produce corresponding sulfinic esters. Thus one‐pot, three‐component synthesis of β,γ‐unsaturated sulfonamides, sulfinyl esters and sulfones have been developed starting from alkenes and sulfur dioxide (reagent and solvent).     

Microwave-assisted and catalyst-free sulfenylation of imidazo[2,1-b]thiazoles with sulfonyl hydrazides in water

Abstract

An efficient microwave-assisted and catalyst-free sulfenylation of imidazo[2,1-b]thiazoles with sulfonyl hydrazides has been developed in water. This method is practical and environmental friendly, and can be performed within a short reaction time. The sulfenylation reaction shows high regioselectivity, and excellent functional-group compatibility, giving the desired products in moderate to good yields.     

Cu-catalyzed direct C-H thiolation of electron-rich arenes with arylsulfonyl hydrazides

An efficient Cu-catalyzed direct C–H thiolation of electron-rich arenes with arylsulfonyl hydrazides has been developed. Various mono(or bis)-thioether products were obtained in moderate to good yields. Mechanistic studies suggest that the reaction likely proceeds through free-radical formation including arylthio radical and sulfonyl radical, while both disulfanes and sulfonothioates are the major thiolation species in this transformation.     

Visible light induced decomposition of sulfonyl hydrazides using Pd/ZrO2 nanocomposite photocatalyst

A new approach to synthesis of thiosulfonates has been developed under mild conditions without any oxidants and promoting reagents through a Pd/ZrO₂ nanocomposite photocatalyst catalyzed decomposition of sulfonyl hydrazides. This protocol gave the products in moderate yields, comparable to the best results reported so far. Finally, a plausible reaction mechanism was proposed.     

Oxidation of sulfinic acids with dinitrogen tetraoxide: isolation of sulfonyl nitrites

Several sulfonyl nitrites were successfully isolated as brown unstable crystals upon treating sulfinic acids with dinitrogen tetraoxide.     

Nickel‐Catalyzed N‐Alkylation of Acylhydrazines and Arylamines Using Alcohols and Enantioselective Examples

A borrowing‐hydrogen reaction between amines and alcohols is an atom‐economic way to prepare alkylamines, ideally with water as the sole byproduct. Herein, nickel catalysts are used for direct N‐alkylation of hydrazides and arylamines using racemic alcohols. Moreover, a nickel catalyst of (S )‐binapine was used for an asymmetric N‐alkylation of benzohydrazide with racemic benzylic alcohols.     

Efficient electrosynthesis of sulfinic esters via oxidative cross-coupling between alcohols and thiophenols

A new protocol for S O bond formation was developed by electrochemical oxidative cross-coupling between alcohols and thiophenols. With this strategy, a series of valuable sulfinic ester derivatives were synthesized up to 96% yield from basic starting materials. A preliminary mechanistic investigation reveals that this reaction involves oxygen reduction reaction (ORR).     

Radical Heck-type reaction of styrenes with sulfonyl hydrazides on water at room temperature

Herein, metal-free radical Heck-type reaction of styrenes with sulfonyl hydrazides to synthesize vinyl sulfones is developed. The reaction is performed under economical TBAI/TBHP system on water in open air at room temperature, which proceeds through the radical addition to styrenes followed by hydrogen-abstraction. When compared to known approaches for the synthesis of vinyl sulfones from alkenes, this radical Heck-type strategy is practical, green and does not go through HI elimination process. Furthermore, this protocol can be expanded to the iodosulfonylation of alkynes for the synthesis of iodovinyl sulfones.     

砜类化合物合成研究进展

砜类化合物具有广谱的生物活性,广泛应用于化学、医药、农药、材料科学等领域。同时作为强吸电子基团,砜类化合物可以通过碱和亲电试剂反应延长碳链,因此该类化合物的合成方法引起了国内外研究人员的高度重视,本文结合国内外学者对这方面的相关研究,重点从硫醚氧化、磺酰氯的磺酰化和亚磺酸盐的偶联三个方面对近几年来砜类化合物合成方法进行了综述。     

Non-expensive,open-flask and selective catalytic systems for the synthesis of sulfinate esters and thiosulfonates

Two simple and efficient methods for the synthesis of sulfinate esters and thiosulfonates from sodium salts of sulfinic acids are described. Different alcohols were converted into the corresponding sulfinate esters in good yields and purity in an open flask. By the adjustment of the reaction conditions thiosulfonates could also be obtained in a very short reaction time.     

Ag-catalyzed sulfonylation-peroxidation of alkenes with sulfonyl hydrazides and T-hydro

The sulfonylation-peroxidation of alkenes with sulfonyl hydrazides and T-hydro was developed. The Ag-catalyzed three-component peroxidation provides a method for synthesis of a variety of β-sulfonyl peroxides, which could be converted into various sulfone derivatives.     

Destabilizing Predictive Copper-Catalyzed Click Reactions by Remote Interactions with a Zinc-Porphyrin Backbone

In order to obtain new supramolecular ligands that build up around a zinc-porphyrin scaffold, we envisioned to access sulfonyl triazole intermediates by well-known copper-catalyzed click reactions. Unexpectedly, these triazole intermediates do not form due to the presence of the zinc-porphyrin moiety at close proximity of the active copper species. Indeed, the copper catalyst undergoes a different chemo-selective reaction pathway reacting with traces of alcohols or water from the media that behave as effective nucleophiles leading to sulfonyl imidates or sulfonyl amides covalently connected to the zinc-porphyrin. We show that copper-catalyzed click reactions can follow different reaction mechanisms when the catalytic events occur at close proximity of a zinc-porphyrin unit which likely acts as a Lewis acid to stabilize otherwise inaccessible reaction intermediates.