Selective Synthesis of Sulfonamides and Sulfenamides from Sodium Sulfinates and Amines.

An effective method was explored for the selective synthesis of sulfonamides and sulfenamides using sodium sulfinates and amines as starting materials. This method offers mild reaction conditions, a broad substrate scope, high efficiency, and readily accessible materials, making it suitable and an alternative strategy for the preparation of a variety of biologically or pharmaceutically active compounds.

Selective Construction of C-S/S-N Bonds from N-Substituted O-Thiocarbamates and Indoles under Transition-Metal-Free Conditions.

A method for the selective construction of S-N/C(sp2)-S bonds using N-substituted O-thiocarbamates and indoles as substrates is reported. This protocol features good atom utilization, mild conditions, short reaction time, and wide substrate scope, which can provide a convenient path for the functionalization of indoles. In addition, the reaction could be scaled up on gram scale, showing potential application value in industry synthesis.

Cobalt/Salicylaldehyde-Enabled C-H Alkoxylation of Benzamides with Secondary Alcohols under Solvothermal Conditions.

C-O bond formation via C-H alkoxylation remains a challenge, especially coupling with a secondary alcohol, due to its low activity and sterically encumbered property. Here, we report a general and effective cobalt-catalyzed oxidative cross-coupling of benzamides with secondary alcohols via C-H alkoxylation reaction under solvothermal conditions, enabled by a salicylaldehyde/cobalt complex. The protocol features easy operation without additives, broad substrate scope, and excellent functional tolerance. The applicability is proven by the gram-scale synthesis and modification of natural products.

Transition-Metal-Free Synthesis of Polyfluoro-Polyarylmethanes via Direct Cross-Coupling of Polyfluoroarenes and Benzyl Chlorides.

The transition-metal-free direct cross-coupling between polyfluoroarenes and benzyl chlorides is reported. In this strategy, a variety of polyfluoro di-, tri- and tetra-arylmethanes was efficiently prepared with good to excellent yields in the presence of Mg turnings via a one-pot procedure. Significantly, this method provides a general approach for the synthesis of polyfluorinated polyarylmethanes.

Thiolation of Terminal Alkynes with Thiuram Disulfide Reagents Using Water as the Hydrogen Source: Stereoselective Synthesis of (Z)-Vinyl Sulfides.

A stereoselective and environmentally friendly thiolation of terminal alkynes was reported. Thiuram disulfide reagents (tetramethylthiuram disulfide and tetraethylthiuram disulfide) that reacted with alkynes in dimethyl sulfoxide (DMSO)/H2O could give (Z)-vinyl sulfides in good yields (up to 88%). This protocol features broad substrate scope, good stereoselectivity, high atom economy, good yields, and is transition metal-free. Mechanistic studies revealed that water and DMSO served as hydrogen sources, which greatly highlighted the unique reactivity of this special reaction involving two H-atom donors.

Electrochemical Difunctionalization of Alkenes: Simultaneous Construction of C-Se and C-S Bonds.

Electrochemical oxidation of alkene difunctionalization with simultaneous construction of C-Se and C-S bonds is reported. The products of ß-selenylethyl dithiocarbamates are obtained with CS2, amines, alkenes, and diphenyl diselenides in the absence of any oxidant or metal. Furthermore, the transformation is compatible with various groups. In the preliminary mechanism studies, we propose three possible pathways.

PPh3/I2 Promoted Synthesis of Unsymmetrical Disulfides from Sodium Sulfites and 2-Mercaptobenzo Heterocyclics.

A simple and efficient method for the synthesis of unsymmetrical disulfides is reported. Using sodium sulfites and 2-mercaptobenzo heterocyclic compounds as starting materials, the unsymmetrical sulfur-sulfur bonds could be quickly constructed in the PPh3/I2 reaction system under transition-metal-free conditions. This protocol has the advantages of mild reaction conditions, easily available starting materials, and wide substrate scope, showing potential synthetic value for the synthesis of a diversity of biologically or pharmaceutically active compounds.

Glyoxylic Acid Monohydrate-Promoted Formation of the C-SO2 Bond Starting from Maleimides/Quinones and Sodium Sulfinates.

By using glyoxylic acid monohydrate as a promoter, a wide range of substances containing a C-SO2 bond could be obtained from N-substituted maleimides or quinones and sodium sulfinates. The protocol features mild reaction conditions, short reaction time, and good atomic economics, which provides an alternative protocol for the α-sulfonylation of α,ß-unsaturated ketones.

A decade update on the application of ß-oxodithioesters in heterocyclic synthesis.

The diverse synthesis of heterocyclic compounds has always been one of the popular subjects of organic chemistry. To this end, great efforts have been devoted to developing new reagents and establishing new strategies and methods concerning efficiency, selectivity and sustainability. ß-Oxodithioesters and their enol tautomers (i.e., α-enolic dithioesters), as a class of simple and readily accessible sulfur-containing synthons, have been widely applied in the construction of various five- and six-membered heterocycles (e.g., thiophenes, thiopyrans, thiazoles, pyridines and quinolines) and other useful open-chain frameworks. Due to their unique chemical structures, ß-oxodithioesters bear multiple reaction sites, which enable them to participate in two-component or multicomponent reactions to construct various heterocyclic compounds. In the past decade, the application of ß-oxodithioesters in the synthesis of heterocycles has made remarkable progress. Herein, an update on the recent advances in the application of ß-oxodithioesters in the synthesis of heterocycles during the period from 2013 to 2023/06 is provided. According to the different types of rings concerning heteroatoms in products, this review is divided into five sections under discussion including (i) synthesis of sulfur-containing heterocycles, (ii) synthesis of sulfur and nitrogen-containing heterocycles, (iii) synthesis of nitrogen-containing heterocycles, (iv) synthesis of nitrogen and oxygen-containing heterocycles, and (v) modification to other open-chain frameworks.

Easy S-Alkylation of Arylthioureas and 2-Mercaptobenzothiazoles Using Tetraalkylammonium Salts under Transition-Metal-Free Conditions.

A highly-efficient and practical method for S-alkylation of arylthioureas was reported. Using tetraalkylammonium salts as alkylation reagents, a series of 68 S-substituted aryl-isothioureas were obtained in good to excellent yields under transition-metal-free conditions. The protocol features simple performance, broad functional group tolerance, good to excellent yields, and easily available starting materials, showing potential synthetic value for the preparation of diverse biologically or pharmaceutically active compounds.

One-Pot Synthesis of 1,2-Disubstituted Indoles from 2-Ethynylanilines and Benzaldehydes.

An efficient synthesis of a variety of 1,2-disubstituted indoles from 2-ethynylanilines was developed. Using 2-ethynylanilines and benzaldehydes as starting materials, the target products (1,2-disubstituted indoles) were obtained smoothly through condensation, reduction, and subsequent cyclization. Various functional groups attached to the aryl ring of 1,2-disubstituted indoles were well tolerated. The protocol features easy performance, easily available starting materials, good yield, and a broad substrate scope, showing potential synthetic value for the preparation of a variety of biologically or pharmaceutically active compounds.

Green and Practical Synthesis of Thioenamines and Chromones via Iodine-Catalyzed Cross-Dehydrogenation Coupling Reaction.

An iodine-catalyzed one-pot synthesis of thioenamines and chromones is reported. By using easily available phenyl isothiocyanate, alcohols, and enamines as starting materials, a tandem reaction (nucleophilic addition and the subsequent cross-dehydrogenation coupling) proceeded smoothly to give the desired thioenamines in good to excellent yields. This protocol features simple operation, mild conditions, a broad substrate scope, good atomic economics, and no need to add extra reaction solvents, providing a practical and green route for the synthesis of thioenamines. In addition, this method can also prepare some representative chromones in moderate yields.

One-Pot Synthesis of N,N-Diphenyl-2-benzothiazolamines from 1-(2-Iodophenyl)-3-phenylthioureas and Iodobenzenes.

An efficient copper-catalyzed synthesis of a variety of N,N-diphenyl-2-benzothiazolamines was developed. Starting from substituted 1-(2-iodophenyl)-3-phenylthioureas and substituted iodobenzenes, the reaction proceeded smoothly via a tandem manner in the presence of CuI to afford the corresponding N,N-diphenyl-2-benzothiazolamine derivatives with good functional group tolerance. The protocol features simple performance, easily available starting materials, a one-pot manner, and good functional group tolerance, providing a practical strategy for the preparation of poly-functionalized amines.

Synthesis of Unsymmetric Thiosulfonates Starting from N-Substituted O-Thiocarbamates: Easy Access to the S-SO2 Bond.

Using phenyliodine diacetate as an oxidant and nickel acetate as a promoter, a wide range of unsymmetric thiosulfonates could be furnished easily in moderate to excellent yields starting from N-substituted O-thiocarbamates and sodium sulfinates. This protocol features mild conditions, short reaction times, and high atomic utilization, which can provide an alternative method for the synthesis of unsymmetric thiosulfonates. In addition, the reaction could be scaled up on a gram scale, showing potential application value in industry.

One-Pot Synthesis of Benzoazole-Substituted Thioenamines via a Cross Dehydrogenation Coupling (CDC) Reaction.

An iodine-catalyzed synthesis of benzoazole-substituted thioenamines in a one-pot manner was reported. Using 2-aminothiophenols (or 2-aminophenols or 1,2-phenylenediamines), tetramethylthiuram disulfide (TMTD), and enamines (mainly indoles) as starting materials, the target C(sp2)-S formation products (benzoazole-substituted thioenamines) could be furnished smoothly in good yields. The reaction might proceed through an electrophilic substitution pathway in a cross dehydrogenation coupling (CDC) manner. The protocol is metal-free and features easy performance, a one-pot manner, a good functional group tolerance, and good yields.

Iodine promoted cyclization of N,N'-diphenylthiocarbamides with enaminones: a protocol for the synthesis of poly-substituted 2-iminothiazolines.

An iodine promoted cyclization reaction between N,N'-diphenylthiocarbamides and enaminones was achieved, providing a series of poly-substituted 2-iminothiazolines. This protocol is transition metal free and simple to perform, with a broad functional group tolerance and good to excellent yields under mild reaction conditions, showing potential synthetic value for the preparation of a diversity of biologically and pharmaceutically active compounds.

Cs2CO3-Promoted Hydrothiolation of Alkynes with Aryl Thioureas: Stereoselective Synthesis of (Z)-Vinyl Sulfides.

A metal-free Cs2CO3-promoted hydrothiolation of alkynes with aryl thioureas for stereoselective synthesis of (Z)-vinyl sulfides has been reported. Vinyl thioethers were obtained without a metal catalyst in good yields via anti-Markovnikov and cis addition. The protocol features a broad substrate scope of the starting materials, high atom economy, good yields, and exclusive stereoselectivity, showing potential synthetic value for the synthesis of a diversity of (Z)-vinyl thioethers.

A Mild Synthesis of 2-Substituted Benzothiazoles via Nickel-Catalyzed Intramolecular Oxidative C-H Functionalization.

A highly efficient synthetic method for the preparation of 2-aminobenzothiazoles starting from arylthioureas has been reported. By using a nickel catalyst, arylthioureas undergo intramolecular oxidative C-H bond functionalization, giving the desired 2-aminobenzothiazoles in good to excellent yields. This protocol features an inexpensive catalyst, low catalyst loading, mild reaction conditions, a short reaction time, and good to excellent yields, and it can be scaled up easily to a gram scale with almost no yields decreasing.

Chemoselective Chan-Lam Coupling Reactions between Benzimidazoline-2-thiones and Arylboronic Acids.

An efficient Chan-Lam-type methodology for the selective synthesis of S-arylbenzimidazoles and N,S-diarylbenzimidazoles was developed. The selectivity was controlled by varying the amount of the catalyst Cu(OAc)2·H2O, temperature, and solvent switching. These transformations feature a simple protocol, broad functional group tolerance, high selectivity, and good to excellent yields. It is noteworthy that these reactions represent the first examples of the application of the selective Chan-Lam coupling.

Copper(I)-Catalyzed Tandem One-Pot Synthesis of 2-Arylthiobenzothiazoles and 2-Arylthiobenzoxazoles in Water.

An efficient tandem process for the preparation of 2-arylthiobenzothiazoles has been developed. By condensation of 2-aminobenzenethiol with tetramethylthiuram disulfide (TMTD), 2-mercaptobenzothiazoles was in situ generated, which susequently underwent coupling with iodobenzenes to give the desired 2-arylthiobenzothiazoles fluently in a one-pot manner. This method can also be used for the synthesis of 2-arylthiobenzoxazoles. Inexpensive metal catalyst and ligand, mild reaction temperature, and water as solvent make this protocol practically valuable and useful in organic synthesis.