Staudinger/aza-Wittig reactions utilizing a novel linear polymer-supported triphenylphosphine as a modified liquid-phase reagent

A new triphenylphosphine reagent linked to a linear maleimide-styrene copolymer is synthesized and is found to be effective for the formation of a variety of imines via the Staudinger/aza-Wittig reaction. This linear polymer-supported triphenylphosphine has a unique solubility behavior and provides for a simple means of purifying the desired imine from the phosphine oxide by-product. The reactivity of this polymeric reagent is superior to that of the cross-linked polymer-supported phosphine reagent.     

Feasibility study of symmetric solution of molecular argon flow inside microscale nozzles

The computational cost of numerical methods in microscopic-scales such as molecular dynamics (MD) is a deterrent factor that limits simulations with a large number of particles. Hence, it is desirable to decrease the computational cost and run time of simulations, especially for problems with a symmetrical domain. However, in microscopic-scales, implementation of symmetric boundary conditions is not straight-forward. Previously, the present authors have successfully used a symmetry boundary condition to solve molecular flows in constant-area channels. The results obtained with this approach agree well with the benchmark cases. Therefore, it has provided us with a sound ground to further explore feasibility of applying symmetric solutions of micro-fluid flows in other geometries such as variable-area ducts. Molecular flows are solved for the whole domain with and without the symmetric boundary condition. Good agreement has been reached between the results of the symmetric solution and the whole domain solution. To investigate robustness of the proposed method, simulations are conducted for different values of affecting parameters including an external force, a flow density, and a domain length. The results indicate that the symmetric solution is also applicable to variable-area ducts such as micro-nozzles.     

Ultrasound-promoted greener synthesis of aryl-14-H-dibenzo[a,j]xanthenes catalyzed by NH4H2PO4/SiO2 in water

Silica supported ammonium dihydrogen phosphate (NH(4)H(2)PO(4)/SiO(2)) is found to be a recyclable heterogeneous catalyst for a rapid and efficient synthesis of various aryl-14-H-dibenzo[a,j]xanthenes with excellent yields using ultrasonic irradiation. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times and milder conditions.     

A rapid and convenient synthesis of gem-bis(dithiocarbamate) derivatives from primary aliphatic amines,carbon disulfide,and aromatic aldehydes using boron trifluoride-diethyl etherate

An efficient route for the synthesis of gem-bis(dithiocarbamate) derivatives is developed using dithiocarbamic acid salts generated from primary aliphatic amines and CS₂. The method offers high yields, employs mild reaction conditions, and demonstrates excellent functional group compatibility. The structures of the products were confirmed spectroscopically and by X-ray analysis.     

Amino Phosphate Monoesters: A Convenient Source of 2-Alkylamino-3-methoxy-3-phenylpropionates via Aziridinium Ions

The synthesis of a series of amino ethers was carried out in a two-step method involving phosphorylation of the corresponding amino alcohols and subsequent double displacement via an aziridinium intermediate. The new products were obtained in good yields with excellent regioselectivity.     

A new pregnane glycoside from Gomphocarpus fruticosus growing in Egypt

Phytochemical investigation of Gomphocarpus fruticosus (L.) Ait. of Egyptian origin afforded the new pregnane glycoside lineolon-3-O-[β-D-oleandropyranosyl-(1–4)-β-D-cymaropyranosyl-(1–4)-β-D-cymaropyranoside], along with six known compounds. The structures of the isolated compounds were elucidated on the basis of extensive spectroscopic evidences derived from 1D, 2D NMR experiments, mass spectrometry and by comparing their physical and spectroscopic data to literature. These included the triterpenoids 3β-taraxerol, 3β-taraxerol acetate and betulinic acid, which are identified for the first time in G. fruticosus and the cardenolides uzarigenin, gomphoside and calotropin.     

Study of complexation of phenylaza-15-crwon-5, 4-nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag+, Tl+ and Pb2+ ions in methanol by competitive potentiometry

The complexation reaction of phenylaza-15-crwon-5, 4- nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag⁺, Tl⁺ and Pb²⁺ ions in methanol solution have been studied by a competitive potentiometric method. The Ag⁺/Ag electrode used both as an indicator and reference electrode in a concentration cell. The emf of cell monitored as the crown ethers concentration varies through the titration. The stoichiometry and stability constants of resulting complexes have been evaluated by MINIQUAD. The stoichiometry for all resulting complexes was 1:1. The stability of these metal ions with derivatives of 15-crown-5 are in order phenylaza-15-crown-5 > Benzo-15-crown-5 > 4-nitrobenzo-15-crown-5, and for the each used crown ethers are as Pb²⁺ > Ag⁺ > Tl⁺. The effect of the substituted group on the stability of resulting complexes was considered. The obtained results are novel and interesting.     

Silica supported sodium hydrogen sulfate （NaHSO4/SiO2）： A mild and efficient reusable catalyst for the synthesis of aryl-14-H-dibenzo [aj]xanthenes under solvent-flee conditions

A simple and efficient procedure for the preparation of aryl- 14-H-dibenzo [aj]xanthenes by a one-pot condensation reaction of 2-naphthol and aryl aldehydes, in the presence of silica supported sodium hydrogen sulfate （NaHSO4/SiO2） as a catalyst and in the absence of solvent has been developed. The present method offers several advantages such as excellent yields, short reaction time （10-30min）, mild condition, simple work-up, and the use of a cheap and environmentally friendly catalyst with remarkable reusability.     

Copper–birhodanine complex immobilized on Fe3O4 nanoparticles: DFT studies and heterogeneous catalytic applications in the synthesis of propargylamines in aqueous medium

Heterogeneous magnetic nanocatalyst, Fe₃O₄@SiO₂–Ligand–Cu (II) MNPs, reveals high catalytic performance within the synthesis of propargylamines using the multicomponent coupling reaction of aldehydes, phenylacetylene and secondary amines in water as a solvent. The substantial feature of this organic–inorganic hybrid magnetic nanocatalyst is the capability of straightforward separation of the reaction mixture by an external magnet which was retrieved ten times without significant loss of catalytic activity. This methodology has other advantages such as subordination to the principles of green chemistry and avoiding the use of expensive and harmful organic solvents. To study the stability and actual structure of birhodanine derivative–copper (II) complex, DFT calculations were also performed.