Noncovalent interactions in C–S bond formation reactions

Organosulfur compounds are omnipresent in many drugs, natural products, and functional materials; therefore, methodologies of C–S bond formation reactions are desirable in synthesis. The recent trend to control many chemical reactions by cooperative multiple weak interactions have emerged as one of the popular topics in supramolecular catalysis. Herein, we have made a collection of literature which utilizes multiple noncovalent interactions like H-bonding, solvent bonding, S–H···π, C–H···π, π–π stacking, charge-transfer complexation, etc. toward aryl C–S bond-formation reactions

Direct c-s bond functionalization of benzyl mercaptan

Cleavage of a C–S bond of benzyl mercaptan led to formation of a new C–C bond during (Z)-selective alkenylation of nitriles using 1,10-phenanthroline as organocatalyst and tBuOK as a base. Furthermore, we have shown that the cascaded functionalization of benzylic C–S and aryl–halide bonds could be done in one pot. 1H NMR study and kinetic experiments also helped to establish the mechanism of the reaction

λ3-Iodanes as visible light photocatalyst in thioacetalization of aldehydes

Introduction of an iodine(III) reagent as visible-light photocatalyst for chemoselective dithioacetalization has been the limelight of the current methodology. The mechanistic investigations reveal that the reactions proceeded via radical pathway upon light induced hemolytic cleavage of C–I bond of the catalyst. Several dithioacetals were easily accessible at room temperature and environmentally benign condition

Metal-free C–S coupling of thiols and disulfides

In organic synthesis, transition-metal and photoredox-catalysis-based reaction systems are emerging trends for the construction of C–S bonds. Many review articles have recently appeared in this field; however, we present herein an overview of metal-free C–S coupling reactions using thiols or disulfides as sulfur surrogates. The oxidants we have considered include peroxides, tert-butyl nitrite (TBN), DDQ, iodine reagents, and molecular oxygen. In addition, selective electrochemical oxidative transformations are also covered with mechanistic details

N-Iodosuccinimide as bifunctional reagent in (E)-selective C(sp2)−H sulfonylation of styrenes

Herein we report the use of N-iodosuccinimide (NIS) as a bifunctional reagent for a regio- and (E)-selective C(sp2)-H sulfonylation reaction of styrenes. Styrenes and sulfonyl hydrazides treated with NIS and potassium carbonate in ethanol at 70 °C resulted in (E)-vinyl sulfones exclusively with good to excellent yields. NIS, plays a dual role to generate sulfonyl radical from sulfonyl hydrazides at an initial stage and finally gives β-iodosulfone intermediate which was further converted to (E)-vinyl sulfones. Overall, a sustainable method for mild, metal free, convenient, one pot and direct synthesis of (E)-vinyl sulfones from styrenes are demonstrated via a C−S coupling reaction

Dithioacetalization or thioetherification of benzyl alcohols using 9-mesityl-10-methylacridinium perchlorate photocatalyst

We report herein the use of 9-mesityl-10-methylacridinium perchlorate as the visible-light photocatalyst for dithioacetalization or thioetherification of benzyl alcohols in one pot using aerial dioxygen as a terminal oxidant. EPR analysis and Stern–Volmer quenching studies helped to rationalize the single electron transfer (SET) mechanism

S−H⋅⋅⋅π Driven Anti-Markovnikov Thiol-Yne Click Reaction

Herein we demonstrate that an anti-Markovnikov selective thiol-yne-click (TYC) reaction could be achieved between phenyl acetylenes and thiophenols by exploiting a newly identified S−H⋅⋅⋅π non-covalent interaction without using any catalysts, additives and solvents. Natural bond orbital (NBO) analyses also supported that S−H⋅⋅⋅π and cooperative π–π stacking interactions helped to promote this regioselective reaction. The hydrothiolated products were isolated in near quantitative yields. Also, the concept of self-sorting was demonstrated when styrene, phenyl acetylene and thiophenols were reacted in one pot. Owing to the stronger S−H⋅⋅⋅π preference of ethynyl≡H over the vinyl=H hydrogen bond, selectively, TYC product formation was found to be dominating over the thiol-ene-click (TEC) product

Noncovalent Interactions in C–S Bond Formation Reactions

Organosulfur compounds are omnipresent in many drugs, natural products, and functional materials; therefore, methodologies of C–S bond formation reactions are desirable in synthesis. The recent trend to control many chemical reactions by cooperative multiple weak interactions have emerged as one of the popular topics in supramolecular catalysis. Herein, we have made a collection of literature which utilizes multiple noncovalent interactions like H-bonding, solvent bonding, S–H···π, C–H···π, π–π stacking, charge-transfer complexation, etc. toward aryl C–S bond-formation reactions

(Z)-Selective anti-Markovnikov or Markovnikov thiol–yne-click reactions of an internal alkyne by amide hydrogen bond control

Herein, we show exclusive control of stereo and regioselective thiol–yne click (TYC) reactions of internal alkynes via amide hydrogen bond control. By exploiting appropriate hydrogen bonding interactions like N–H⋯S, N–H⋯N and C–H⋯O, either (Z)-selective anti-Markovnikov or Markovnikov products could be obtained for an internal alkyne, exclusively