Palladium(0)-Catalyzed Enantioselective Construction of Multifunctional Piperidine Derivatives from 1,3-Dienes, N-Cyano Imines, and Beyond

An enantioselective (4 + 2) reaction between 1,3-dienes and N-cyano imines has been developed under Pd(0) catalysis, proceeding through a cascade vinylogous addition and intramolecular allylic amination sequence. 2,6-cis-Disubstituted-1,2,3,6-tetrahydropyridines were furnished as single diastereomers in moderate to good yields and enantiocontrol. Moreover, a more challenging three-component (2 + 2 + 2) annulation of 1,3-dienes, N-cyano imines, and activated alkenes was efficiently realized to afford piperidines with high structural complexity, albeit with moderate enantioselectivity.

Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights

The catalytic hydration of cyanamides to ureas has been accomplished employing, for the first time, homogeneous catalysts, i.e. the phosphinous acid complexes [MCl₂(η⁶-p-cymene)(PMe₂OH)] (M = Ru, Os).

Fe3O4@SiO2 nanoparticle supported ionic liquid for green synthesis of antibacterially active 1-carbamoyl-1-phenylureas in water

In the present work, we have designed a novel, heterogeneous and recyclable magnetic Brønsted acidic ionic liquid based on 5-phenyl-1H-tetrazole. The {Fe3O4@SiO2@(CH2)35-phenyl-1H-tetrazole-SO3H/Cl} ([FSTet-SO3H]Cl) was prepared via the immobilization of 5-phenyl-1H-tetrazole-bonded sulfonic acid onto the surface of silica-coated magnetic nanoparticles using 3-chloropropyltriethoxysilane as a linker. The catalyst was characterized by XRD, TEM, FESEM, EDS, TG-DTA, and FT-IR. The ability and high activity of this catalyst were demonstrated in the synthesis of 1-carbamoyl-1-phenylureas with good to excellent yields via a new, simple and one-pot procedure in aqueous media under reflux conditions. This procedure has advantages such as high yields, short reaction times, a simple methodology and work-up process, green reaction conditions, high stability, catalytic activity, and easy preparation, separation and reusability of the catalyst. The synthesis of these compounds was confirmed by FT-IR, 1H NMR, 13C NMR and CHN. In addition, we investigated the biological properties of the 1-carbamoyl-1-phenylureas as newly synthesized compounds. The described catalyst could be easily separated from the reaction mixture by additional magnetic force and reused several times without a remarkable loss of its catalytic activity and any considerable changes in the product yield and the reaction time.

Green synthesis, optical properties and catalytic activity of silver nanoparticles in the synthesis of N-monosubstituted ureas in water

We report the green synthesis of silver nanoparticles by using Euphorbia condylocarpa M. bieb root extract for the synthesis of N-monosubstituted ureas in water. UV-visible studies show the absorption band at 420 nm due to surface plasmon resonance (SPR) of the silver nanoparticles. This reveals the reduction of silver ions (Ag+) to silver (Ago) which indicates the formation of silver nanoparticles (Ag NPs). This method has the advantages of high yields, simple methodology and easy work up.

A simple method for the electrophilic cyanation of secondary amines

Bleach oxidizes trimethylsilyl cyanide to generate an electrophilic cyanating reagent that readily reacts with an amine nucleophile. This oxidative N-cyanation reaction allows for the preparation of disubstituted cyanamides from amines without using highly toxic cyanogen halides.