Asymmetric Binary Acid Catalysis: Switchable Enantioselectivity in Enantioselective Conjugate Hydride Reduction

The exchange of the metal ion from Zr(IV) to Fe(III) leads to a switch in the enantioselectivity of binary acid-catalyzed conjugate hydride reductions. In the presence of Hantzsch ester, γ-indolyl β,γ-unsaturated α-keto esters could be reduced to the desired (S)- or (R)-products, respectively, with good to excellent enantioselectivity (up to 98% ee)

Construction of Axially Chiral Styrenes Linking an Indole Moiety by Chiral Phosphoric Acid

Herein we report a chiral phosphoric acid-catalyzed intermolecular C2 Friedel–Crafts alkylation reaction between ortho-alkynylnaphthols and various 3-substituted indoles, affording axially chiral alkenes with up to 93% yields (E/Z > 20:1) and up to 98% ee under mild reaction condition. Other substituted indole derivatives could be also tolerated in this system, giving the corresponding axially chiral alkenes with high yields and in excellent enantioselectivity

Copper-Catalyzed Synthesis of Benzimidazoles via Cascade Reactions of <i>o</i>-Haloacetanilide Derivatives with Amidine Hydrochlorides

We have developed an efficient method for the synthesis of benzimidazoles via cascade reactions of o-haloacetoanilide derivatives with amidine hydrochlorides. The protocol uses 10 mol % CuBr as the catalyst, Cs2CO3 as the base, and DMSO as the solvent, and no ligand is required. The procedure proceeds via the sequential coupling of o-haloacetoanilide derivatives with amidines, hydrolysis of the intermediates (amides), and intramolecular cyclization with the loss of NH3 to give 2-substituted 1H-benzimidazoles

Photocatalyst-Free Regioselective C–H Thiocyanation of 4‑Anilinocoumarins under Visible Light

In the present study, we describe the successful development of a novel and efficient C­(sp2)–H thiocyanation reaction of electron-rich heteroarenes and arenes with readily available ammonium thiocyanate under visible light exposure. Most importantly, the reaction proceeded smoothly without addition of any photocatalyst or strong oxidant, ultimately minimizing the production of chemical waste. The advantages of this reaction met the requirements of green and sustainable synthetic chemistry and may be widely used in organic synthesis and pharmaceutical chemistry

Synthesis of Sulfur-Containing Trisubstituted Imidazoles by One-Pot, Multicomponent Reaction via Electron Donor–Acceptor Complex Photoactivation

Rapid and efficient construction of multifunctionalized skeletons through a one-pot multicompound domino reaction has been recognized as a simple and practical strategy. Herein, a visible-light-enabled three-component reaction of isothiocyanates, isocyanides, and thianthrenium salt-functionalized arenes is presented, which affords a facile approach to sulfur-containing trisubstituted imidazoles in good yields with a broad substrate scope and excellent functional group tolerance. The byproduct thianthrene is recovered in quantity, thereby ultimately reducing the production of chemical waste. The developed methodology has potential value for the discovery and development of thioimidazole-based drugs

Divergent Coupling of <i>ortho</i>-Alkynylnaphthols and Benzofurans: [4 + 2] Cycloaddition and Friedel–Crafts Reaction

Catalytic direct [4 + 2] cycloaddition reactions and Friedel–Crafts reactions of ortho-alkynylnaphthols with benzofurans have been developed, affording functionalized hydrobenzofuro[3,2-b]chromans and hydroarylation products, respectively, in high yields with high chemoselectivity

Metal-Free Direct Hydrosulfonylation of Azodicarboxylates with Sulfinic Acids Leading to Sulfonylhydrazine Derivatives

<div><p></p><p>A metal-free direct hydrosulfonylation protocol of azodicarboxylates with sulfinic acids has been developed for the construction of sulfonylhydrazine-1,2-dicarboxylates at room temperature. This methodology provides an efficient and practical approach to prepare various sulfonylhydrazine-1,2-dicarboxylates in good to excellent yields, which has the advantages of operation simplicity, environmental friendliness, high atom economy, and mild reaction conditions.</p></div

Radial Type Ring Opening of Sulfonium Salts with Dichalcogenides by Visible Light and Copper Catalysis

Herein, a copper-catalyzed, blue-light-induced free radical type ring opening of sulfonium salts with dichalcogenides has been initially developed. The developed method features an inexpensive copper catalyst and a broad substrate scope, affording practical access to alkyl chalcogenides in high yields. This reaction presents a novel ring-opening model of sulfonium salts, which breaks the limitation that only the nucleophilic ring-opening reaction could form C–heteroatom bonds and C–C bonds

Copper-Catalyzed Domino Synthesis of Nitrogen Heterocycle-Fused Benzoimidazole and 1,2,4-Benzothiadiazine 1,1-Dioxide Derivatives

A convenient copper-catalyzed domino method for the synthesis of nitrogen heterocycle-fused benzoimidazole and 1,2,4-benzothiadiazine 1,1-dioxides has been developed using readily available 2-bromo-<i>N</i>-phenylbenzenesulfonamides and benzimidazole derivatives as the starting materials. The domino process comprises an Ullmann-type <i>N</i>-arylation and intramolecular C–H amination. The inexpensive and efficient copper-catalyzed method should provide a new and useful strategy for for constructing novel, biologically interesting heterocycles containing benzoimidazole and 1,2,4-benzothiadiazine 1,1-dioxide motifs

Photocatalyst-Free Visible-Light-Promoted C(sp²)–S Coupling: A Strategy for the Preparation of <i>S</i>‑Aryl Dithiocarbamates

We have successfully developed a green and efficient multicomponent reaction protocol to synthesize S-aryl dithiocarbamates under visible light. Most appealingly, the reaction can proceed smoothly without adding any transition-metal catalysts, ligands, or photocatalysts while minimizing chemical wastes and metal residues in the end products. The advantages of this method meet the requirements of sustainable and green synthetic chemistry, and it provides a straightforward way to create valuable S-aryl dithiocarbamates