Air Induced Phosphoryl Radical Mediated Stereoselective Hydrosulfonylation of Alkynes <i>via</i> Halogen Atom Transfer: Ingress of <i>Z</i>‑Vinyl Sulfones

The phosphoryl radical is well-known to participate in addition reactions with alkenes/alkynes. Here, we report a novel reaction mode of the phosphoryl radical where it participates in halogen atom transfer (XAT) with electron deficient vinyl halides instead of a facile addition reaction. Nevertheless, in comparison with aryl and alkyl halides, the exploitation of vinyl halides into a carbon radical via XAT is quite rare. This protocol provides an opportunity for direct hydrosulfonylation of numerous internal as well as terminal alkynes to get various Z-vinyl sulfones under environmentally benign conditions. Generation of the phosphoryl radical in the open air, water as a solvent, excellent functional group compatibility, and exceptional chemoselectivity are the attractive features of the present methodology

Reduced Graphene Oxide Supported Copper Oxide Nanocomposites from a Renewable Copper Mineral Precursor: A Green Approach for Decarboxylative C(sp³)–H Activation of Proline Amino Acid To Afford Value-Added Synthons

A green approach for decarboxylative C­(sp³)–H activation of proline amino acid was accomplished by coupling with aldehydes and alkynes to afford α-alkynylated N-substituted pyrrolidines as value-added synthons using reduced graphene oxide supported copper oxide (RGO@CuO) nanocatalysts. The RGO@CuO nanocomposites were obtained by the impregnation of micrometer-sized malachite spheres, as a renewable and sustainable copper mineral precursor, on the graphene oxide (GO) sheets followed by calcination at 300–450 °C for 5 h. The characterization of as-synthesized composites revealed the generation of monodispersed and uniformly embedded copper oxide (CuO) nanoparticles with sizes ranging from 10 to 15 nm on RGO thin sheets via GO as a support as well as indirect template for dissembling and decomposition of micrometer-sized malachite spheres. The RGO@CuO composites were found to be efficient and robust nanocatalysts compared with CuO nanoparticles (NPs) alone. The present method offers several advantages, such as wide substrate scope, and avoids the usage of excess equivalent of substrates with minimal waste generation (E-factor = 0.24) and high reaction mass efficiency (80.7%), and the nanocatalyst was recycled for five times without significant loss in its activity with a negligible leaching of CuO NPs from RGO sheets

Hydromagnesite Rectangular Thin Sheets as Efficient Heterogeneous Catalysts for the Synthesis of 3‑Substituted Indoles via Yonemitsu-Type Condensation in Water

The anisotropic controlled assembly of nanobuilding blocks into uncommon uniform rectangular thin sheet morphology of hydromagnesite (RS-HM) with a high surface area of 110 m²/g was achieved by a simple conventional heating under green reaction condition. The synthesized RS-HM was calcined at 450 °C in the presence of air and resulted in the formation of MgO with a surface area 120 m²/g. RS-HM was found to be a more efficient catalyst than MgO for the synthesis of novel 3-substituted indoles via Yonemitsu-type condensation selectively in excellent yields. The present method has advantages such as environmentally benign, ease to handle, selectivity and excellent yields, low <i>E</i>-factor (0.15) and high atom economy (96%)