An epoxide-opening cyclization/double Smiles rearrangement cascade approach to N-aryl-1,4-benzoxazines and N-arylindolines.

Reported herein is a transition-metal-free protocol for a regio- and diastereoselective synthesis of hydroxyalkyl group-embedded N-arylbenzo[b][1,4]oxazines and N-arylindolines based on an epoxide-opening cyclization/double Smiles rearrangement cascade of p-nosylamide-tethered epoxides. To the best of our knowledge, this is the first report of the integration of epoxide-opening cyclization with Smiles rearrangement in a cascade fashion, enabling simultaneous construction and N-arylation of N-heterocycles. The reaction employs substrates derived from commercially available 2-nitrophenols and easily accessible allylic halides/alcohols, and exhibits a broad substrate scope and delivers the products in high yields.

Base-mediated intramolecular one-pot double-cyclization of epoxide-tethered 2-fluorobenzenesulfonamides: an avenue to 1,4-benzoxazine-fused benzothiaoxazepine-1,1-dioxides.

Herein, we describe the synthesis of hitherto unknown 1,4-benzoxazine-fused benzothiaoxazepine-1,1-dioxides by a NaH-promoted intramolecular one-pot double-cyclization of epoxide-tethered 2-fluorobenzene sulfonamides. Mechanistically, the reactions proceed via an intramolecular epoxide ring-opening followed by an intramolecular nucleophilic aromatic substitution. The high yields, mild conditions, complete regio- and diastereoselectivity, and a wide substrate scope render this protocol well suited for drug discovery efforts.

Cu-Based Nanoparticles as Emerging Environmental Catalysts.

This account provides an overview of current research activities on nanoparticles containing the earth-abundant and inexpensive element copper (Cu) and Cu-based nanoparticles, especially in the field of environmental catalysis. The different synthetic strategies with possible modification of the chemical/ physical properties of these nanoparticles using such strategies and/or conditions to improve catalytic activity are presented. The design and development of support and/or bimetallic systems (e. g., alloys, intermetallic, etc.) are also included. Herein, we report synthetic approaches of Cu and Cu-based nanoparticles (monometallic copper, bimetallic copper and copper (II) oxide nanoparticles/nanostructures) and impregnation of such nanoparticles onto support material (e. g., Co3 O4 nanostructure), along with their applications as environmental catalyst for various oxidation and reduction reactions. Finally, this account provides necessary advances and perspectives of Cu-based nanoparticles in the environmental catalysis.

Enhanced catalytic activity of CuPd alloy nanoparticles towards reduction of nitroaromatics and hexavalent chromium.

The present work reports a surfactant-free, economically feasible chemical route to synthesize bimetallic CuPd alloy nanoparticles under hydrothermal condition. The structural and morphological characterizations of the nanoparticles are carried out by XRD, SEM/EDX, TEM, XPS and BET surface area analyses. The synthetic strategy comprises of 9:1 molar composition of Cu2+ and Pd2+ salt in the aqueous solution. The size of the nanoparticles isca. 3-4nmwith very notable specific surface area of 298m2g-1. The synthesized nanoparticles exhibit excellent catalytic performance towards the aqueous phase reduction of 4-nitrophenol and 4-nitroaniline in the presence of NaBH4 as a reducing agent. Furthermore the CuPd alloy nanoparticles also demonstrate remarkable activity towards reductive conversion of toxic Cr(VI) to less toxic Cr(III) at room temperature. Bimetallic CuPd alloy nanoparticles are catalytically more active and exhibit good recyclability in comparison to the monometallic Cu and Pd due to synergistic effect.