Synthesis of pyrimido[6,1-a]isoquinolines via a one-pot, four-component reaction

An efficient one-pot synthesis of pyrimido[6,1-a]isoquinoline-1-carboxylate derivatives is described. This involves the four-component reaction between primary amines, alkyl acetoacetates, isoquinoline and trichloromethylchloroformate (diphosgene) under mild conditions at ambient temperature.     

Synthesis of heterocyclic [3.3.3]propellanes via a sequential four-component reaction

A highly chemoselective heteroannulation protocol for the synthesis of unreported polysubstituted heterocyclic [3.3.3]propellanes has been developed by sequential four-component reaction of ninhydrin, malononitrile, primary amines, and dialkyl acetylenedicarboxylates under mild conditions in water. To the best of our knowledge, there are no previous reports for the synthesis of these classes of heterocyclic [3.3.3]propellanes. The merit of this sequential Knoevenagel condensation/enamine formation/Michael addition/cyclization sequence is highlighted by its high atom-economy, excellent yields, the use of water as reaction media, and the efficiency of production without the use of any activator or metal promoters. This synthesis serves as a nice addition to group-assistant-purification (GAP) chemistry in which purification via chromatography and recrystallization can be avoided, and the pure products were obtained simply by washing the crude products with 95% ethanol.     

Dye-doped nanostructure polypyrrole film for electrochemically switching solid-phase microextraction of Ni(II) and ICP-OES analysis of waste water

A nanostructure fiber based on conducting polypyrrole synthesized by an electrochemical method has been developed, and used for electrochemically switching solid-phase microextraction (ES-SPME). The ES-SPME was prepared by the doping of eriochrome blue in polypyrrole (PPy-ECB) and used for selectively extracting the Ni(II) cation in the presence of some transition and heavy metal ions. The cation-exchange behavior of electrochemically prepared polypyrrole on stainless-steel with and without eriochrome blue (ECB) dye was characterized using ICP-OES analysis. The effects of the scan rate for electrochemical synthesis, uptake and the release potential on the extraction behavior of the PPy-ECB conductive fiber were studied. Uptake and release time profiles show that the process of electrically switched cation exchange could be completed within 250 s. The results of the present study point concerning the possibility of developing a selective extraction process for Ni(II) from waste water was explored using such a nanostructured PPy-ECB film through an electrically switched cation exchange.     

On cyclic and n-cyclic monotonicity of bifunctions

In the recent literature, the connection between maximal monotone operators and the Fitzpatrick function is investigated. Subsequently, this relation has been extended to maximal monotone bifunctions and their Fitzpatrick transform. In this paper we generalize some of these results to maximal \(n\) -cyclically monotone and maximal cyclically monotone bifunctions, by introducing and studying the Fitzpatrick transforms of order \(n\) or infinite order for bifunctions.     

Solvent-free synthesis of penta-substituted pyrroles: one-pot reaction of amine, alkyl acetoacetate, and fumaryl chloride

A novel, convenient, and efficient approach to the synthesis of penta-substituted pyrroles has been reported based on the multicomponent reaction. Solvent-free condition for the formation of enaminones from primary amines and alkyl acetoacetates and it's reaction with fumaryl chloride lead to the formation of pyrroles that have halide, CH₂CO₂H, ester functional groups, and two alkyl substitutions.     

Microcolumn LC enantioseparation of chiral compounds using diol silica gel functionalized with vancomycin crystalline degradation products

Vancomycin crystalline degradation products (CDPs) have been introduced as one of the newest and most interesting derivatives of vancomycin for enantiomer separation of a wide variety of chiral compounds. In this attempt, a chiral stationary phase (CSP) has been prepared using diol silica gel based on vancomycin CDPs which led to a new chiral selector with new functionality of functional groups on a microcolumn LC. Different kinds of mobile phases were examined to realize the behavior of the chiral selector in separation of atropine, fluoxetine, amlodipine, mandelic acid, alanine, and phenylalanine which were separated successfully on this column. Good results were obtained by using a polar mobile phase containing water, methanol, and acid additives for separation of chiral acidic compounds and amino acid samples. Considerable results were obtained for analysis of basic compounds by using polar organic mobile phase (POP) containing methanol, acid and base additives. These results can be associated with the presence of the carboxylic acid groups present in new CSP by using a diol silica gel.     

Highly Selective and Sensitive Tin(II) Membrane Electrode Based on a New Synthesized Schiff's Base

Studies on complex formation of tris(3‐(2‐hydroxybenzophenone)propyl)amine (THPA) with a number of metal ions in acetonitrile solution revealed the occurrence of a selective 1 : 1 complexation of the proposed ligand with Sn²⁺ ion. Consequently, THPA was used as a suitable neutral ionophore for the preparation of a polymeric membrane‐selective electrode. The electrode exhibits a Nernstian behavior with a slope of 29.4±0.3 mV per decade and a detection limit of 2.0×10^?7 M. It also showed a good selectivity for Sn²⁺ ions in comparison with some of group A and B metal ions over a wide concentration range of 5.0×10^?7–1.0×10^?1 M. Improved selectivity was achieved compared to the best selectivity recently reported by other authors for tin(II). The electrode was successfully applied to the determination of Sn²⁺ ion in waste water and various canned products.     

Novel heterocyclic β-nitroenamines-based on a one-pot three-component reaction: a facile synthesis of fully substituted 1H-pyrrolo[1,2-a]-fused-1,3-diazaheterocycles

A one-pot multicomponent synthesis of a novel class of 2,3-dihydro-1H-pyrrolo[1,2-a]imidazoles, 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrimidines, and 2,3,4,5-tetrahydro-1H-pyrrolo[1,2-a][1,3]diazepines, starting from simple and readily available inputs including diveres diamines, l,l-bis(methylthio)-2-nitroethen and diaroylacetylene, in excellent yields is described.     

A novel, fast and efficient one-pot four-component procedure for preparation of some alkyl spiro[indeno[1,2-b]quinoxaline-11,3′-pyrrolizine]-2′-carboxylates

In this study we report a novel one-pot reaction which stereoselectively affords alkyl spiro[indeno[1,2-b]quinoxaline-11,3′- pyrrolizine]-2′-carboxylates via the four-component condensation of ninhydrin, phenylenediamines, proline, and acrylic acid derivatives. The reactions were run in ethanol and completed at less than 25 min and the products were obtained in very good yields. The stereochemistry of the products was deduced on the basis of the ¹H NOESY and comparison with the related systems.