Synthesis of Indolo[1,2-a]quinoxalinones through Palladium/Copper-Cocatalyzed Oxidative Isocyanide-Insertion Cyclization of Indoles and Hydrolysis of Enamines

A novel Pd/Cu-cocatalyzed isocyanide-insertion cyclization of indoles and hydrolysis of enamines has been developed for the construction of indolo[1,2-a]quinoxalinones. A secondary amine group on the N-phenylindole skeleton acts as an important directing groups that participates in activation of the C(2)-position of the indole and the subsequent isocyanide-insertion cyclization. The fragile generated enamine bond is easily hydrolyzed by the acid medium to give the corresponding quinoxalinone skeleton. This regioselective and high-yielding transformation, which avoids the use of hazardous CO gas, might be extendable to syntheses of natural polycyclic products.

Primary and secondary amine material based on crosslinked polystyrene: synthesis and initial application for multiresidue pesticides analysis

Weak anion exchange sorbent based on cross-linked polystyrene with primary secondary amine group was prepared by substitution nucleophilic reaction (SN2) between methylene chloride group and 1,2-ethylene diamine. The effect of factors, namely the weight ratio of amine over methylene chloride, reaction time and temperature on nitrogen percentage were studied using experimental design approach. The amination yield rose as all of factors increased but was reduced while both temperature and time increased simultaneously. Nitrogen percentage of the products were varied from 4.0% to 6.3%. Sorbents with predicted capacity of 4.5%, 5.0%, 6.3%, and 6.5% were synthesized. The results showed that the actual capacities of the products were close to the predictions, especially for those in the experimental domain, indicating a good model that can be used to prepare sorbents of any desired capacity. The sorbent application ability of multiresidue pesticides analysis in food were initially investigated through both aspects: interference elimination and analyte content conservation.

Two Propanediurea-based Cucurbituril Analogues: Bis-ns-TD[8] and NH-ns-TD[4]

Two new cucurbituril members, one containing two equivalent cavities and the other having an active secondary amine group, were synthesized by condensation of propanediurea (2,4,6,8-tetraazabicyclo[3.3.1]nonane-3,7-dione) with formaldehyde. These two macrocycles exhibit excellent thermal stability, and their structures were confirmed by single-crystal X-ray diffraction, 1H NMR spectroscopy, and high-resolution mass spectrometry.

Development of new spectrophotometric method for estimation of tenofovir disoproxil fumarate using MBTH reagent

A new simple, sensitive and specific procedure has been developed for determination of tenofovir disoproxil fumarate in bulk and pharmaceutical dosage forms using MBTH reagent. The purpose of this analytical validation procedure is to validate it by laboratory experiments to prove that the method meets the minimum standards for laboratory use. 3-methyl-2-bezothiazoline hydrazone reacts with the secondary amine group of tenofovir in the presence of oxidizing agent, ferric chloride. The resulting apple green coloured chromogen when measured spectrophotometrically in visible region (i.e., 400-800nm) shows a maximum absorbance at 626.5nm. This method can be successfully applied for the determination of drug content in pharmaceutical formulations. The results of analysis have been validated statistically.DOI: http://dx.doi.org/10.3329/icpj.v4i4.22620 International Current Pharmaceutical Journal, March 2015, 4(4): 378-381

Sulfonated Poly(Fluorenyl Ether Ketone) Membranes with Suppressed Semi-Interpenetrating Crossover and Enhanced Proton Selectivity for Vanadium Redox Flow Batteries

A series of hybrid membranes with special microstructure, based on sulfonated poly (fluorenyl ether ketone) ionomer (SPFEK, IEC=1.74 mequiv.g-1) and secondary amine group containing SiO2(SiO2–NH–NH2), has been successfully designed and prepared for vanadium redox flow battery (VRB) application. The hybrid membranes are prepared by simply adding KH792 into the SPFEK solution in N,N’-dimethylacetamide (DMAc), followed by dispersion, co-condensation and solvent casting. The water uptake, mechanical property, proton conductivity, (VO)2+permeability and single cell performance are investigated in order to understand the relationship between morphology and property of the membranes. The hybrid membranes show dramatically improved proton selectivity when compared with SPFEK. The vanadium ion (VO)2+permeability through the hybrid membrane is about 10 times lower than that of virgin SPFEK. The columbic efficiency and energy efficiency of the single cell of the hybrid membrane are higher than the SPFEK membrane. The results inidicate that hybrid membranes of this type are promising for VRBs.

(Anilino{(Z)-2-[(E)-5-bromo-3-methoxy-2-oxidobenzylidene]hydrazin-1-ylidene-κ2O2,N2}methanethiolato-κS)(4,4′-dimethyl-2,2′-bipyridine-κ2N,N′)zincN,N-dimethylformamide monosolvate

The asymmetric unit of the title compound, [Zn(C15H12BrN3O2S)(C12H12N2)]·C3H7NO, contains two independent molecules with a similar structure. The doubly deprotonated Schiff base ligandO,N,S-chelates to the metal atom, and the three coordinating atoms along with one N atom of the substituted 2,2′-bipyridine ligand constitute the square plane of the distorted square pyramid surrounding the metal atom. The apical site is occupied by the second N atom of the substituted 2,2′-bipyridine. The secondary amine group of the Schiff base dianion forms a hydrogen bond to the O atom of the dimethylformamide solvent. In the crystal, the phenyl ring of one of the two Schiff base anions is disordered over two positions in a 1:1 ratio. The crystal studied is a racemic twin.