One-pot synthesis of sulfonamides from methyl sulfinates using ultrasound

Azasulfur(iv) derivatives of sulfite and sulfinate esters by formal S-S bond insertion of dichloramines

Azasulfur(vi) compounds such as sulfoximines and sulfonimidamides are attractive due to the unique properties of the S[double bond, length as m-dash]N bond. While the synthesis of these carbon-attached sulfonimidoyl derivatives is well-established, the situation is different for their heteroatom-bound counterparts. In this work, we propose azasulfur(iv) esters as platform chemicals that can be derivatized to obtain all types of SVI[double bond, length as m-dash]N functional groups, among these are the poorly accessible, all-heteroatom imidosulfate esters. Using a chloroamination workflow established here, S-S bond-containing structures such as elemental sulfur or diaryl disulfides can be transformed into imidothionyl or sulfinimidoyl chlorides, which are easily esterified or amidated. Thus, chloramines serve as a versatile [N] and [Cl+] source, and by using them in the context reported here, we advance the set of mild synthetic methods as the latest toolbox member to cover even more of the azasulfur(iv) and (vi) chemical space.

Bypassing Sulfonyl Halides: Synthesis of Sulfonamides from Other Sulfur-Containing Building Blocks

This review disclosed synthetic approaches to sulfonyl amides from non-sulfonyl halogenated precursors. Known methods were systematized into groups and subgroups according to the type of starting organosulfur compound. Thiols, disulfides, and sulfonamides form a group of S(II)-containing precursors, which are used in oxidative amination reactions. An important and versatile group for oxidative amination is represented with S(IV)-containing compounds, i. e., sufinates, sulfinamides, DMSO, N-sulfinyl-O-(tert-butyl)hydroxylamine, etc. A series of S(VI)-containing precursors for amination reactions (except sulfonyl halides) include sulfonic acids, sulfonyl azides, thiosulfonates, and sulfones. All approaches are represented with the most prominent examples of the resulting sulfonamides, which could be obtained in high yields mostly via short reaction sequences. Promising electrochemical methods for the preparation of sulfonamides from thiols, disulfides, sulfonamides, sulfinic acid derivatives, and dimethyl sulfoxide under mild and green conditions are also highlighted.

Transsulfinamidation of Sulfinamides with Amines

Metal- and additive-free transsulfinamidation of N-unsubstituted sulfinamides and N-pivaloyl-protected sulfinamides with various amines is reported. With this method, both N-monosubstituted and N,N-disubstituted sulfinamides were obtained in good yields simply by heating. Preliminary experiments also indicate that alcohols can be used as nucleophiles instead of amines and can provide sulfinate esters.

Complementary strategies for synthesis of sulfinamides from sulfur-based feedstock

We describe a straightforward one-pot reductive protocol for the synthesis of sulfinamides from sulfonyl chlorides. This method enables the preparation of sulfinamides with a broad range of functional groups. Furthermore, we have expanded a known oxidative pathway to sulfinamides starting from thiols. These methods together provide a general strategy for the synthesis of sulfinamides from common sulfur-based feedstock that is available with large structural and functional group diversity.

Nickel(II)-Catalyzed Addition of Aryl and Heteroaryl Boroxines to the Sulfinylamine Reagent TrNSO: The Catalytic Synthesis of Sulfinamides, Sulfonimidamides, and Primary Sulfonamides

We report a redox-neutral Ni(II)-catalyzed addition of (hetero)aryl boroxines to N-sulfinyltritylamine (TrNSO). The reactions use a catalyst generated from the combination of commercial, air-stable NiCl₂·(glyme) and a commercially available bipyridine ligand, and deliver sulfinamide products. The scope of the reaction is established using a sulfonimidamide synthesis, in which the initially formed sulfinamides undergo oxidative chlorination with the inexpensive and safe chlorinating agent, trichloroisocyanuric acid (TCCA), to produce sulfonimidoyl chlorides as key intermediates. These are combined in situ with a range of amines to deliver sulfonimidamides. The sulfonimidoyl chlorides can also be elaborated into primary sulfonamides via hydrolysis, and sulfonimidoyl fluorides via treatment with fluoride. These transformations are all achieved using one-pot procedures. Unprotected, primary sulfinamides are also available. For larger-scale reactions, the catalyst loading can be reduced to 1 mol %.

Electrochemical Synthesis of Sulfinic Esters via Aerobic Oxidative Esterification of Thiophenols with Alcohols

A method for the electrochemical synthesis of sulfinic esters by aerobic oxidative coupling of thiophenols and alcohols has been developed. Using electrons as the redox reagent and O2 in air as the oxygen source, the reactions proceeded smoothly at room temperature, even for a gram-scale preparation. No use of catalyst, clean redox reagent, green and abundant oxygen source, and mild reaction conditions make this strategy eco-friendly.

Sulfinamide Synthesis Using Organometallic Reagents, DABSO, and Amines

We report the synthesis of sulfinamides using organometallic reagents, a sulfur dioxide reagent, and nitrogen based-nucleophiles. The addition of an organometallic reagent to the commercially available sulfur dioxide surrogate, DABSO, generates a metal sulfinate which is reacted with thionyl chloride to form a sulfinyl chloride intermediate. Trapping the sulfinyl chlorides in situ with a variety of nitrogen nucleophiles delivers sulfinamides in 32–83% yields. Each stage of the process is performed at room temperature, and the total reaction time is only 1.5 h.

Facile Assembling of Novel 2,3,6,7,9-pentaazabicyclo- [3.3.1]nona-3,7-diene Derivatives under Microwave and Ultrasound Platforms

Reactions of a series of 3-oxo-2-arylhydrazonopropanal derivatives with two molar ratio of ammonium acetate afforded a library of tetrasubstituted 2,3,6,7,9-pentaazabicyclo[3.3.1]nona- 3,7-diene derivatives in good to excellent isolated yields. The reaction was activated with triethylamine catalyst under three different heating modes: thermal, ultrasonic and microwave irradiating conditions in ethanol solvent. The structures of the isolated products were fully characterized by spectral and analytical data as well as X-ray single crystal of selected examples.

Tandem one-pot synthesis of 2-arylcinnolin-6-one derivatives from arylhydrazonopropanals and acetoacetanilides using sustainable ultrasound and microwave platforms

Several 2-arylcinnolin-6(2H)-one derivatives were synthesized via tandem annulation of a large number of 3-oxo-2-arylhydrazonopropanals with acetoacetanilide under three different heating modes (conventional heating, ultrasound and microwave irradiation) using triethylamine in ethanol. The factors affecting the optimization of the annulation process were thoroughly studied. The annulated structures were established on the basis of ¹H and ¹³C NMR and MALDI-TOF/MS spectral data as well as single crystal X-ray analysis.

Several 2-arylcinnolin-6(2H)-one derivatives were synthesized via tandem annulation of a large number of 3-oxo-2-arylhydrazonopropanals with acetoacetanilide under three different heating modes.

Sucrose and KF quenching system for solution phase parallel synthesis

The KF, sucrose (table sugar) exploited as quenching system in solution phase parallel synthesis. Excess of electrophiles were covalently trapped with hydroxyl functionality of sucrose and due to polar nature of sucrose derivative was solubilize in water. Potassium fluoride used to convert various excess electrophilic reagents such as acid chlorides, sulfonyl chlorides, isocyanates to corresponding fluorides, which are less susceptible for hydrolysis and subsequently sucrose traps these fluorides and dissolves them in water thus removing them from reaction mixture. Various excess electrophilic reagents such as acid chlorides, sulfonyl chlorides, and isocyanates were quenched successfully to give pure products in excellent yields.

An efficient ultrasonic-mediated one-pot synthesis of 2,3,6,7,9-pentaazabicyclo[3.3.1]nonanes via a N,N-dimethylformamide dimethylacetal catalyzed Mannich-like reaction

A novel and straightforward method for one-pot synthesis of functionalized 2,3,6,7,9-pentaazabicyclo[3.3.1]nonane derivatives has been developed.

Ultrasound-assisted regio- and stereoselective synthesis of bis-[1′,4′-diaryl-1-oxo-spiro-benzosuberane-2,5′-pyrazoline] derivatives via 1,3-dipolar cycloaddition

A novel bis-[spiro-benzosuberane-2,5′-pyrazoline] derivatives were synthesized via 1,3-dipolar cycloaddition under ultrasonic irradiation.

Ph3P/CCl4 as a highly efficient reagent for one-pot N-alkylation of sulfonamides from alcohols: a rapid route to N-alkyl sulfonamides synthesis

A mild, efficient, and selective protocol for the one-pot N-alkylation of sulfonamides with alcohols using triphenylphosphine and carbon tetrachloride is described. In this method, treatment of alcohols with a mixture of triphenylphosphine, carbon tetrachloride, and potassium sulfonylamide salts in refluxing anhydrous DMF furnishes the corresponding N-alkyl sulfonamides in good to excellent yields. This protocol is highly efficient for various structurally diverse alcohols and potassium sulfonylamide salts. In this paper the influence of solvents and various reagents as sources for electrophilic-halogen instead of carbon tetrachloride in combination with triphenylphosphine have been examined. This protocol demonstrates the selectivity between primary and secondary alcohols. A plausible mechanism for this protocol has been described.

3,2-Hydroxypyridinone (3,2-HOPO) vinyl sulfonamide and acrylamide linkers: Aza-Michael addition reactions and the preparation of poly-HOPO chelators

The HOPO vinyl sulfonamide 3 and the corresponding HOPO acrylamide 10, were easily prepared by short synthetic sequences. Investigation of the aza-Michael reactions of these linkers showed that they proceed at a higher rate in solvent systems containing water. The scope and limits of the aza-Michael reactions of 3 and 10 were examined. Reagents 3 and 10 reacted cleanly with piperazine to give the corresponding adducts which were deprotected to give the di-HOPO ligands 7 and 16. Reaction of HOPO acrylamide 10 with 1,4,7-triazacyclononane gave the tris-adduct 17 which was deprotected to give the desired tris-HOPO ligand 18. Overall, the aza-Michael reactions of 3 and 10 appear to be governed not only by the solvent but also by the nature of the amine and the solubility of the reaction intermediates.