Parthasarathi Das

In this study, we report a metal‐ and photocatalyst‐free protocol for synthesizing ( E )‐β‐amidovinyl sulfones under visible light via an electron donor–acceptor (EDA) complex formed between thiosulfonates and DMAP in DMSO. This method offers a mild, efficient, and cost‐effective approach to access β‐amidovinyl sulfones from enamides with E ‐selectivity and excellent functional group tolerance.

A new strategy for the rapid and efficient synthesis of N-sulfonyl formamidines has been developed through the activation of N,N-dimethylformamide (DMF), assisted by (Methyl)thianthrenium salt under ambient conditions. The protocol offers a metal and oxidant-free process, utilizing a bench-stable and recyclable thianthrenium salt as an activator, via a convenient procedure. The protocol exhibits broad substrate compatibility and scalability. The practical utility of the method has been further demonstrated through the late-stage functionalization of pharmaceutically relevant drug molecules.

Herein, we report a new approach for the C3–H functionalization of azaindoles through thianthrenium salt formation. This versatile azaindole thianthrenium salt intermediate participates in a range of cross-coupling reactions, including Suzuki, Heck, Sonogashira, Hiyama, and Barluenga–Valdés-type coupling. By combining the site-selectivity of thianthrenation with the robustness of these electrophilic reagents, this protocol grants access to a large variety of azaindole derivatives that are otherwise challenging to prepare with comparable levels of selectivity, diversity, and practicality.

Late-stage installation of carboxylic acid groups via carbonylation is often limited by the use of toxic CO gas or expensive surrogates. While chloroform-derived CO has proven effective in two-chamber systems for aminocarbonylation, carbonylative Suzuki coupling, and ester formation from aryl iodides, direct hydroxycarbonylation remains challenging. Herein, we report a mild and efficient palladium-catalyzed hydroxycarbonylation of aryl thianthrenium salts using water as the nucleophilic source and chloroform as a CO surrogate in a two-chamber (COware) setup. The unique reactivity of aryl thianthrenium salts facilitates regioselective late-stage functionalization (LSF) of structurally complex molecules.

In situ thianthrenium activation enables regioselective amination and phosphorylation of N -vinyl azoles and enamides, affording a new class of fluorescent ketene aminals and α-phosphoryl scaffolds under mild, metal-free conditions.

External ligand-free Pd-catalyzed arylation achieving an exclusive switch in regioselectivity from α- to β position of N -vinyl-7-azaindoles via an N -oxide activation strategy.

A step-economic and efficient palladium-catalyzed protocol for regioselective C-2 arylation of 7-azaindoles with arylthianthrenium salts has been developed under base- and ligand-free conditions. The reaction proceeds smoothly with broad substrate scope, requires low catalyst loading, exhibits excellent functional group tolerance, and provides C-2 arylated products in moderate to excellent yields. Moreover, given the ready availability of arylthianthrenium salts from simple arenes, this strategy offers a valuable platform for the late-stage functionalization of structurally complex and bioactive molecules. The origin of the observed regioselectivity has been elucidated through density functional theory (DFT) calculations.

Herein, we report a practical and efficient approach for the monoselective N-methylation of arylamide substrates using (methyl)thianthrenium triflate as an effective methylating agent. This strategy enables late-stage selective N-monomethylation of structurally complex bioactive molecules with excellent efficiency and selectivity. Notably, the protocol facilitates monoselective N-(¹³C-methyl) incorporation, providing access to isotopically labeled compounds of pharmaceutical interest for drug discovery and development. The versatility and broad applicability of this approach are demonstrated through the successful synthesis of marketed drugs such as enzalutamide and apalutamide. Its operational simplicity, versatility, selectivity, and scalability make this protocol an efficient tool for late-stage diversification and isotope labeling of amide-based scaffolds.

A solvent-controlled CuF₂-catalyzed Chan-Lam coupling of saccharin with arylboronic acids is reported, enabling the chemodivergent synthesis of N-arylsaccharin derivatives in dichloroethane and methyl 2-(N-arylsulfamoyl)benzoates in MeOH. A saccharin-DMAP zwitterion complex was isolated, which provided crucial mechanistic insights for the product distribution. This chemodivergent synthesis transformed saccharin into versatile synthons for the synthesis of a tianeptine analogue and an endothelin antagonist analogue, highlighting its pharmaceutical relevance.