Girijesh Kumar Verma

A highly regioselective [Cp*Co(CO)I₂]‐catalyzed addition of 1,3‐diketones to terminal alkynes at room temperature has been achieved using Cu(OTf)₂ as a co‐catalyst. The reaction of 1,3‐diketones substituted at active methylene carbon with phenyl acetylenes having an electron‐withdrawing group or a bulky group results in the formation of the 2‐alkenylated 1,3‐dicarbonyl product, but phenyl acetylenes with electron donating group led to the formation of tetrahydronaphthalene and terphenyl.

A cost-effective and eco-friendly straightforward synthesis of highly diversified thiazoloquinoline scaffolds is successfully achieved via one-pot four-component cascade reaction utilizing α-enolic dithioesters, cysteamine, aldehydes, and cyclic 1,3-diketones in water–PEG-400. The new efficient domino protocol generates two rings by the concomitant formation of C–C (two), C–N (two), and C–S multiple bonds presumably involving a sequence of N,S-acetal formation, Knoevenagel reaction, aza–ene reaction, imine–enamine/keto–enol tautomerization, and N-cyclization as key steps. The merit of this protocol is highlighted by its easily available and economical starting materials, operational simplicity, efficient utilization of all the reactants, clean reaction profile, simple workup procedure, and tolerance of a wide variety of functional groups.

A novel, efficient route to substituted 1-N-(het)aryl/NH-2-(het)aryl-3-cyanoindoles and related pyrrolo-fused heterocycles such as thienopyrroles, pyrroloindoles, and pyrazolopyrroles has been reported. The overall protocol involves sequential cycloamination of readily available 2-[2-bromo(het)aryl]-3-(het)aryl-3-(methylthio)acrylonitrile precursors with primary amines or amides via two key C–N bond-forming processes, one base-mediated intermolecular and the other Cu-catalyzed intramolecular arylamination leading to N(1)–C(2) and N(1)–C(7a) bond formation, respectively, in a two-step one-pot procedure.

An operationally simple and efficient one-pot direct access to pyrroles has been achieved by annulation of α-oxoketene- N , S -acetals with β-nitrostyrenes catalyzed by In(OTf) ₃ under solvent-free conditions.

An operationally simple and efficient approach to hitherto unreported and synthetically demanding 1,3-oxathiolan-2-ylidenes has been developed. The approach involves a cascade [2+3] heteroannulation of α-enolic dithioesters with epoxides promoted by non-nucleophilic moderate base Cs₂CO₃ at room temperature. Typical features of this strategy include metal-free mild reaction conditions, atom-economy, high yields, and efficacy of forming two consecutive C–S and C–O bonds, and one ring in a single stroke. MeSH is the only by-product, and the stereochemistry of the exocyclic α-oxoketene moiety of 1,3-oxathiolane was assigned to have Z-configuration.