Switchable synthesis of 3-alkenyl succinimides and maleimides has been achieved from Michael addition and oxidative cross-coupling reaction of α-oxo ketene dithioacetals and maleimides by switching different reaction conditions. In the presence of 30 mol% of CH3SO3H in DCE at 120 oC, Michael addition reaction of α-oxo ketene dithioacetals and maleimides occurred to afford 3-alkenyl succin-imides in 40-90% yields, whereas in the presence of 30 mol% of Pd(OAc)2 in DMF at 20 oC, 3-alkenyl maleimides were obtained in 40-80% yields from the oxidative cross-coupling reaction of α-oxo ketene dithioacetals with maleimides. The presupposition of directing groups onto the substrates is not required in Michael addition reaction. The method can extend to gram scale.

Minute amounts of supported Au nanoparticles on TiO2 (0.1 mol%) catalyze quantitatively at room temperature the transfer hydrogenation of azoarenes to hydrazoarenes by ammonia borane complex, in ethanol as solvent. At 1 mol% catalyst loading level and 2.5 molar equivalents of ammonia borane the process occurs instantaneously. The catalyst is recyclable and reusable. In the absence of reducing agent, hydrazoarenes undergo smooth Au/TiO2-catalyzed aerobic oxidation back to azoarenes.

Aerobic photochemistry is a rapidly advancing field that provides sustainable solutions for traditional transformations. In this study, 3H-phenothiazin-3-one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This new photocatalytic method uses a low catalyst loading (0.05 mol%), molecular oxygen as the sole oxidant, and a blue LED lamp as the irradiation source. It can be applied to the oxidation of both alkyl-aryl and alkyl-alkyl sulfides. Moreover, the method is also applicable in the synthesis of the known pharmaceutically active compounds Modafinil and Sulforaphane.

A pyrrolidine-catalyzed three-component reaction of azlactone, N,O-acetal and alcohol for the synthesis of α,β-diamino ester was reported. The N,O-acetal served as the imine equivalent to occur Mannich reaction with azlactone, and the in situ generated α-functionalized azlactone subsequently underwent a ring-opening process in the presence of alcohol. A series of α,β-diamino esters were obtained in 36–99% yields under mild reaction conditions. The product could be synthesized on gram-scale and transformed into the α,β-diamino acid.

The palladium (II) catalyzed direct C3-(sp2)-H alkenylation of five membered heterocyclic aldehydes has been developed using 3-aminobutanoic acid as a catalytic transient directing group. A wide range of heterocyclic aldehydes reacted with various acrylates to afford highly site-selective C3-alkenylated products. This method features an exclusive E-selective alkenylation at the C3-position of heterocyclic aldehydes with a broad substrate scope. The protocol also proved to be useful to construct the mechanochromic luminogen.

In this study, we focused on the synthesis of tetraazamacrocycles, an essential class of macrocyclic compounds with applications in coordination chemistry, pharmaceuticals, and catalysis. To accomplish this, we developed a ligand-controlled palladium-catalyzed allylic substitution approach using bicyclic bridgehead phosphoramidite (briphos) ligands. This approach allowed us to selectively achieve [1+1] and [1+2] allylic aminations between allylic diols and diamines, while avoiding the formation of cyclic [1+1] products. By combining this approach with sequential acetylation and allylic amination, we successfully synthesized tetraazamacrocycles with ring sizes ranging from 16 to 38. These findings demonstrate the potential of a sequential allylation strategy for synthesizing complex molecules with broad applications in the fields of chemistry, pharmaceuticals, and medicine.

This work describes the palladium(II)-catalyzed regioselective C8-H olefination of 1-naphthamides. Interestingly, naphthamide fused lactam 2,3-dihydro-1H-benzo[de]isoquinolin-1-one derivatives were also synthesized in the case of a particular class of napthamides. This protocol was found well compatible with a diverse range of acrylates and styrenes leading to product formation in good yields along with a wide functional group tolerance. The developed strategy was further applied to the synthesis of different drug derivatives.

Mixing i-PrI and DABCO in solvent EtCN gave two quaternary ammonium salts (QASs) quantitatively, one of which is monocationic (QAS-1) and the other is dicationic (QAS-2). These QASs were found to catalyze hydrosilylation of alkynes with hydrosilanes (HAH) without the aid of metal and metalloid catalysts. This organocatalysis can be applied to a variety of alkynes: terminal/internal aryl and alkyl alkynes with/without a functional group. With dihydrosilanes (H2Si), the HAH occurred with high E-selectivity through syn addition, which was exclusively observed when using terminal alkyl alkynes, irrespective of a hydrosilane used. A scalable HAH is also feasible. The H-Si unit remaining in alkenylsilanes derived from H2Si is available for dehydrogenative alkynylation and N-heteroarylation under zinc-pyridine catalysis. This synthetic application delivers unique silicon compounds that have, for instance, alkyl, aryl, alkenyl, and alkynyl groups in a single molecule. Mechanistic studies suggested that alkynes activated by QASs irreversibly react with hydrosilanes that become more nucleophilic by the coordination of EtCN. A radical pathway is unlikely. The QAS catalysts can be recovered and reused at least 5 times.

The mono-α-arylation of 2-tetrahydropyranyl O-protection of hydroxyacetone is reported. When using a catalyst system comprised of [Pd(cinnamyl)Cl]2 and the JosiPhos ligands PhPF-tBu or (4-CF3Ph)PF-tBu, such transformations are achieved with ortho-substituted aryl bromides and triflates in the presence of potentially contending functionalities including chloro groups.

Herein, Bi(OTf)3-catalyzed Friedel-Crafts-type annulation of sulfonyl o-hydroxyacetophenones with benzofused cycloethers is described. This single-step strategy provides a variety of functionalized dibenzofused medium-size (9–12) oxacycles through the formation of carbon-carbon and carbon-oxygen single bonds. Further, the oxidative application of target oxacycles was investigated. The chemical structures of the key products were determined based on the single-crystal X-ray analysis. In the overall process, water was generated as the byproduct.

We describe the preparation of S-perfluoroalkyl benzodithiazole trioxides as radical perfluoroalkylating reagents. Their syntheses were performed on a multi-gram scale by an oxidative cyclization connecting the nitrogen of a sulfoximine and a sulfur atom previously introduced in the ortho position of this group. The structures and properties of these new molecules were carefully examined by X-Ray diffraction, DFT calculations and cyclic voltammetry. These data clearly highlight the enhanced reactivity of these cyclic sulfoximines compared to their open analogues. This was confirmed by photoredox catalysis experiments that revealed interesting reactivity, most especially for the introduction of di- and monofluoroalkyl chains.

In this work, a single-atom cobalt-catalyzed transfer hydrogenation (TH) of azides is reported under mild conditions (at 30 ℃ in 30 min) using NH2NH2.H2O as the hydrogen source. Employing this protocol, a wide range of azides were transformed to their corresponding amines. This methodology was extended towards the synthesis of several important N-substituted pyrroles from azides in one-pot manner. The control experiments suggested, the transfer hydrogenation favoured by electron withdrawing substituents and one-pot pyrrole synthesis favoured by electron-donating substituents. The recyclability test revealed the catalysts could be recycled up to 7th times without significant loss in the catalytic activity.

Phtalimidine finds wide pharmaceutical applications and its deuterated derivative is supposed to exhibit enhanced stability towards metabolism. In this work, an electrochemically reductive deuteration strategy from phthalinmide to phtalimidine-d2 was achieved with D2O as a deuterium source at the reagent level in common solvents. This approach showed broad compatibility with a variety of functional groups. Mechanistic investigations assisted by electrochemical analysis revealed a 4-electron reduction pathway, and the coupled anodic oxygen evolution collectively maintains a neutral to mild basic conditions for the ongoing electrochemical reaction.

In the present study, for the first time environmentally friendly deep eutectic solvents (DESs) are used as reaction media to perform an efficient, simple and straightforward photocatalytic amide synthesis at room temperature using thioacids and amines. This method features mild conditions, a broad substrate scope, high yields (≤99%) under ambient conditions with air and moisture tolerance. Moreover, the applied operationally mild reaction conditions tolerate the presence of several different functional group substituents on the amine counterpart. Finally, the developed approach allows the recycling of the reaction medium and catalyst for at least three consecutive cycles without a significant decrease in the reaction yield

Herein, we report a one-pot viable protocol to synthesize tetrasubstituted 2-aminothiophenes engaging readily accessible α-enolic dithioesters and abundant fumaronitrile under metal-free conditions at room temperature in open air. The reaction proceeds via successive Michael-type addition/intramolecular cyclization/isomerization cascades. The added features are benign conditions, exclusive regio- and chemoselectivity, excellent atom-/step-economy, easy purification, and tolerance of wide range of functional groups of a diverse electronic and steric nature. This protocol not only provided a robust and modular approach to various 2-aminothiophenes in moderate to excellent yields, but also demonstrated the potential of dithioesters and fumaronitrile in the challenging intermolecular 100% atom-economic cross-coupling reactions widening the arsenal of synthetic methods.

A protocol for the synthesis of 2,3-dihydrofurans by reductive denitrogenation/ring contraction of 6-membered cyclic nitronates was developed. The process utilizes cheap Raney® nickel both as catalyst and stoichiometric agent without the need for high-pressure equipment. The products are formed in high purity and column chromatography is often not required. Studies on the substrate scope, functional group tolerance, and mechanism were performed. The developed approach provides a straightforward two-step access to densely substituted 2,3-dihydrofurans from nitrostyrenes and alkenes.

A copper-catalyzed direct C(sp2)−H bond aminosulfonylation of maleimides is demonstrated. This protocol enables concurrent construction of C(sp2)−N and C(sp2)−SO2 bonds in one-step and features high efficiency, broad substrate scopes, good functional-group tolerance, and mild reaction conditions. Preliminary mechanistic studies indicate that the reaction probably involves a radical way. Significantly, this method is applicable to synthesize derivatives of pharmaceuticals such as Desloratadine, Fluoxetine, Atomoxetine, and Maprotiline.

A mild photocatalyzed approach to achieve the α-alkylation of esters via formation of an α -radical is disclosed here. Cesium enolates of esters were generated in situ using Cs2CO3 as a base. A subsequent photocatalyzed oxidation at the α-carbon of these enolates produced an α-radical that was added into activated alkenes. This is the first example accessing the α-carbon radical of esters in photoredox catalyed transformations.

Application of a binary Ga-based catalyst system for the coupling of CO2 and aziridines to form oxazolidinones is presented. It has been possible to optimize the catalyst system for the selective formation of a single regioisomer, in excellent yield, under relatively mild reaction conditions. The optimized catalyst system has been successfully applied to a range of substituted aziridines derived from styrene oxide. It has been observed that aziridines bearing two aromatic substituents result in piperazine formation through an unexpected dimerization reaction. These piperazine products can be selectively formed in the absence of CO2 or are favoured at lower reaction temperatures. A detailed DFT study into the reaction mechanism for the formation of both products has been carried out and an unusual ligand assistance in the case of oxazolidinone synthesis has been identified. More specifically, this ligand interaction promotes the initial ring-opening of the aziridine and this work presents the first fully elucidated mechanism involving this intermediate.

A I2–DMSO mediated approach to introduce −OCD3 into pyrroles in situ via multicomponent cascade cyclization reaction using methyl ketones, aniline, ethyl benzoylacetate and CD3OD as readily available substrates is reported. This process realizes introduction of −OCD3 into the Hantzsch pyrrole synthesis and synthesis of deuterated alkoxy-substituted pyrroles with formation of one C–C bond, one C–O bond and two C–N bonds in one pot. Notably, this conversion has good substrate compatibility (62 examples) and eliminates of the need for anhydrous and anaerobic operation.