A solvent-free green synthesis of N-sulfonylformamidines is reported via the direct condensation of N,N-dimethylformamide dimethyl acetal (DMF-DMA) and sulfonamide derivatives at room temperature.The described method avoids the use of metal catalysts as well as hazardous solvents, which are not permitted for pharmaceutical manufacture, for the reactions or isolation of products. Hence, the current work presents a fast and efficient alternative to earlier reported methods. The mild nature of the procedure is demonstrated by varied functional group tolerance. † Electronic supplementary information (ESI) available. See
An efficient copper-catalyzed intermolecular hydroindolation reaction of terminal aryl alkynes to expeditiously synthesize bis(indolyl)alkanes in moderate to high yields is described. The double nucleophilic addition of two molecules of indole to one molecule of alkyne occurs in a tandem manner through an anti-Markovnikov pathway. Various arenes and alkynes allow for this transformation. Preliminary mechanistic study sheds light on the observed regioselectivity involving a Cu-vinylidene complex, and 3-styryl-1H-indole as probable intermediates.
Copper chalcogenide nanoparticles (CuS) synthesized for the first time from a single-source precursor, CuSPh, act as highly efficient and reusable heterogeneous catalyst for regioselective amination of N, N-dimethylbenzylamines with various azoles. The reaction involves N-H/C-H cross-dehydrogenative coupling (CDC) and demonstrates wide functional group tolerance. It provides highly selective access to N-alkylated benzotriazoles, N-alkylated 1,2,3-triazoles and 4-phenyl-1,2,3-triazoles, and N-alkylated carbazoles in 70-89% yields under solvent-free conditions. The CuS nanocatalyst has been characterized by PXRD, XPS, SEM-EDX, and HR-TEM analysis. Mechanistic studies suggest that the reaction follows a radical pathway and involves an iminium ion intermediate.
An efficient and facile method to synthesize N-Mannich bases has been developed using an inexpensive copper(I) bromide/air catalyst system at ambient temperature. A cross-dehydrogenative coupling of N,N-dimethylarylamines occurs efficiently with aromatic heterocyclic amides (oxindoles, isatins), cyclic amides (lactams), simple amides (benzamide), as well as imides (succinimide, phthalimide) to furnish the corresponding amidated/imidated derivatives in good to excellent yields. Preliminary mechanistic and isotope-labeling studies suggest the reaction follows a radical pathway and involves an iminium ion intermediate.
Copper chalcogenide nanoparticles (CuS) supported on graphene oxide (GO) have been synthesized for the first time from CuS, and used as highly efficient heterogeneous catalysts for oxidative ortho-selective C-H aminomethylation of phenols with N,N-dimethylbenzylamines. The NPs (30-80 nm) have been characterized by HRTEM, SEM-EDX, PXRD, FTIR, Raman, ICP-AES and XPS analyses. The NP catalyzed sp-sp cross dehydrogenative coupling (CDC) features a broad substrate scope, excellent functional group tolerance, high yields, use of an inexpensive and reusable copper catalyst, mild conditions, and no need for pre-functionalization of substrates.
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