Sequential Ugi Four‐Component Reaction (4‐CR)/CH Activation Using (Diacetoxyiodo)benzene for the Synthesis of 3‐(Diphenylmethylidene)‐2,3‐dihydro‐1H‐indol‐2‐ones

A sequential Ugi four‐component reaction (4‐CR)/C? H activation using (diacetoxyiodo)benzene is reported. This process is a five‐component reaction of aromatic aldehydes, aniline derivatives, isocyanides, phenylpropiolic acid (3‐phenylprop‐2‐ynoic acid), and (diacetoxyiodo)benzene for the synthesis of 3‐(diphenylmethylidene)‐2,3‐dihydro‐1H‐indol‐2‐ones. This procedure offers several advantages such as good yields, high bond‐forming efficiency, selectivity, and short reaction times.     

Photo absorption of ‐coumaric acid in aqueous solution: RISM‐SCF‐SEDD theory approach

Photo absorption properties of p‐coumaric acid, the chromophore of photoactive yellow protein, in aqueous solution were investigated by means of reference interaction site model self‐consistent field with spatial electron density distribution (RISM‐SCF‐SEDD) method. RISM‐SCF‐SEDD is a combination methodology of electronic structure theory and statistical mechanics for molecular liquids. Here, time‐dependent density functional theory was coupled with RISM equation to study the electronic structure of p‐coumaric acid in aqueous system. Excitation energies of the chromophore in its neutral, two monoanionic and dianionic forms were computed to elucidate the effect of the deprotonation and solvation on the spectroscopic properties. We found that solvation strongly affects the excitation character of the chromophore, especially for phenolate anion and dianion. The free energy difference among the four protonation states is also discussed. © 2017 Wiley Periodicals, Inc.     

Piperazine‐functionalized nickel ferrite nanoparticles as efficient and reusable catalysts for the solvent‐free synthesis of 2‐amino‐4H‐chromenes

Piperazine‐functionalized nickel ferrite (NiFe₂O₄) nanoparticles were synthesized as recoverable heterogeneous base catalysts using a routine method. The synthesized materials were characterized using various spectroscopic techniques such as infrared, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, thermogravimetry analysis, and vibrating sample magnetometry. Catalytic efficiency was investigated in the synthesis of 2‐amino‐4H‐chromene derivatives via a one‐pot three component reaction of aldehyde and malononitrile with β or α‐naphthol/5‐methyle resorcinol under solvent‐free conditions with good to high yields. This method is operationally simple and has several advantages such as good to high yield, short reaction times, solvent‐free conditions, and easy synthesis. Moreover, the catalyst was recovered easily using an external magnet and reused three times without distinctive loss in catalytic activity.     

A new third‐order calibration method with application for analysis of four‐way data arrays

A novel third‐order calibration algorithm, alternating weighted residue constraint quadrilinear decomposition (AWRCQLD) based on pseudo‐fully stretched matrix forms of quadrilinear model, was developed for the quantitative analysis of four‐way data arrays. The AWRCQLD algorithm is based on the new scheme that introduces four unique constraint parts to improve the quality of four‐way PARAFAC algorithm. The tested results demonstrated that the AWRCQLD algorithm has the advantage of faster convergence rate and being insensitive to the excess component number adopted in the model compared with four‐way PARAFAC. Moreover, simulated data and real experimental data were analyzed to explore the third‐order advantage over the second‐order counterpart. The results showed that third‐order calibration methods possess third‐order advantages which allow more inherent information to be obtained from four‐way data, so it can improve the resolving and quantitative capability in contrast with second‐order calibration especially in high collinear systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Efficient Multi‐component Synthesis of Highly Substituted Imidazoles Utilizing P2O5/SiO2 as a Reusable Catalyst

Phosphorus pentoxide supported on silica gel (P₂O₅/SiO₂) has been used as an efficient and reusable catalyst for the one‐pot pseudo four‐component synthesis of 2,4,5‐trisubstituted imidazoles from benzil or benzoin, aldehydes, and ammonium acetate. It was also used for four‐component preparation of 1,2,4,5‐tetrasubstituted imidazoles from benzil or benzoin, aldehydes, primary amine, and ammonium acetate under thermal solvent‐free conditions. The remarkable features of this new procedure are high conversions, cleaner reaction, simple experimental and work‐up procedures and also the catalyst can be easily separated from the reaction mixture and reused several times without any loss of its activity.     

Polyoxometalate immobilized on MOF‐5 as an environment‐friendly catalyst for the synthesis of poly‐functionalized 3‐pyrrolin‐2‐ones

A polyoxometalate immobilized on MOF‐5 (POM/MOF‐5) material has been synthesized and evaluated for the diversity‐oriented synthesis of poly‐functionalized 3‐pyrrolin‐2‐ones via pseudo‐four‐component reaction between dialkyl acetylenedicarboxylate, amines, and aldehyde. The catalyst can be separated from the reaction mixture and reused at least five times with superior activity.     

Methods for parallel computation of SCF NMR chemical shifts by GIAO method: Efficient integral calculation,multi-Fock algorithm,and pseudodiagonalization

We implemented our gauge-including atomic orbital (GIAO) NMR chemical shielding program on a workstation cluster, using the parallel virtual machine (PVM) message-passing system. On a modest number of nodes, we achieved close to linear speedup. This program is characterized by several novel features. It uses the new integral program of Wolinski that calculates integrals in vectorized batches, increases efficiency, and simplifies parallelization. The self-consistent field (SCF) step includes a multi-Fock algorithm, i.e., the simultaneous calculation of several Fock matrices with the same integral set, increasing the efficiency of the direct SCF procedure. The SCF diagonalization step, which is difficult to parallelize, has been replaced by pseudodiagonalization. The latter, widely used in semiempirical programs, becomes important in ab initio type calculations above a certain size, because the ultimate scaling of the diagonalization step is steeper than that of integral computation. Examples of the calculation of the NMR shieldings in large systems at the SCF level are shown. Parallelization of the density functional code is underway. © 1997 by John Wiley & Sons, Inc. J Comput Chem 18: 816–825, 1997     

Cu(OTf)2 Catalyzed Synthesis of Bis(5‐methyl‐2‐furyl)methanes by Condensation of 2‐Methylfuran with Carbonyl Compounds under Solvent Free Conditions

A facile and efficient one‐pot three‐component synthesis of bis(5‐methyl‐2‐furyl)methanes has been achieved via the reaction of 2‐methylfuran with a series of aliphatic and aromatic aldehydes and aliphatic ketones in presence of copper(II) triflate under solvent free conditions. The bis(5‐methyl‐2‐furyl)methanes were obtained in 34% –72% yields and the catalyst was recycled up to four successive cycles without much loss in catalytic activity.     

On the induced‐fit mechanism of substrate‐enzyme binding structures of nylon‐oligomer hydrolase

We present a detailed computational investigation of the induced‐fit motion in a nylon‐oligomer hydrolase (NylB) upon substrate binding. To this aim, we resort on the recently introduced parallel cascade selection molecular dynamics approach, allowing for an accelerated access to the set of conformational changes from an open‐ to a closed‐state structure to form the enzyme‐substrate complex in a specific induce‐fit mechanism. The structural investigation is quantitatively complemented by free energy analyses within the umbrella sampling algorithm accompanied by weighted histogram analysis. We find that the stabilization free energy is about 1.4 kcal/mol, whereas the highest free energy barrier to be overcome is about 2.3 kcal/mol. Conversely, the energetic contribution for the substrate binding is about 20 kcal/mol, as estimated from Generalized Born/Surface Area. This means that the open‐close induced‐fit motion could occur frequently once the substrate binds to the open state of NylB. © 2014 Wiley Periodicals, Inc.     

Magnetic Nanoparticle Supported Ionic Liquid Assisted Green Synthesis of Pyrazolopyranopyrimidines and 1,6‐diamino‐2‐oxo‐1,2,3,4‐tetrahydropyridine‐3,5‐ dicarbonitriles

A simple and eco‐friendly green protocol was used for synthesis of pyrazolopyranopyrimidines via four‐component reaction of hydrazine hydrate, ethyl acetoacetate, barbituric acid or dimethyl barbituric acid, and aromatic aldehydes under thermal and solvent‐free conditions in the presence of magnetic nanoparticle supported silica bonded n‐propyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane chloride (MNPs@DABCO⁺Cl^?) as an efficient, recyclable heterogeneous catalyst. MNPs@DABCO⁺Cl^? also catalyzed the synthesis of 1,6‐diamino‐2‐oxo‐1,2,3,4‐tetrahydropyridine‐3,5‐dicarbonitrile derivatives by four‐component reaction of hydrazine hydrate, malononitrile, ethyl cyanoacetate and ketones under thermal and solvent‐free conditions at 80 °C. These methods are practical and offer many advantages, such as high yields, short reaction times, and simple work‐up.     

A roadmap for poly(ethylene oxide)‐block‐poly‐ε‐caprolactone self‐assembly in water: Prediction,synthesis, and characterization

Numerical self‐consistent field (SCF) lattice computations allow a priori determination of the equilibrium morphology and size of supramolecular structures originating from the self‐assembly of neutral block copolymers in selective solvents. The self‐assembly behavior of poly(ethylene oxide)‐block‐poly‐ε‐caprolactone (PEO‐PCL) block copolymers in water was studied as a function of the block composition, resulting in equilibrium structure and size diagrams. Guided by the theoretical SCF predictions, PEO‐PCL block copolymers of various compositions have been synthesized and assembled in water. The size and morphology of the resulting structures have been characterized by small‐angle X‐ray scattering, cryogenic transmission electron microscopy, and multiangle dynamic light scattering. The experimental results are consistent with the SCF computations. These findings show that SCF is applicable to build up roadmaps for amphiphilic polymers in solution, where control over size and shape are required, which is relevant, for instance, when designing spherical micelles for drug delivery systems © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 330–339     

Xanthan Sulfuric Acid as an Efficient Biodegradable and Recyclable Catalyst for the One‐Pot Synthesis of α‐Amino Phosphonates

A convenient and efficient procedure for the synthesis of α‐amino phosphonates by a one‐pot, three‐component condensation of aldehydes, amine, and diethyl phosphite in the presence of xanthan sulfuric acid as a bio‐supported catalyst under solvent‐free conditions has been developed. A wide range of α‐amino phosphonates have been obtained in high to excellent yields. Furthermore, the catalyst can be recovered simply and reused several times in subsequent reactions.     

Determination of thiol compounds by HPLC and fluorescence detection with 1,3,5,7‐tetramethyl‐8‐bromomethyl‐difluoroboradiaza‐s‐indacene

Altered levels of thiols in biological fluids are considered to be an important indicator for several diseases. In this article, 1,3,5,7‐tetramethyl‐8‐bromomethyl‐difluoroboradiaza‐s‐indacene is proposed as a fluorescent derivatization reagent for the determination of thiols including glutathione, cysteine, N‐acetylcysteine, and homocysteine by HPLC. Under the optimized derivatization and separation conditions, a baseline separation of all the four derivatives has been achieved using isocratic elution on an RP C₈ column within 26 min. With fluorescence detection at 505 and 525 nm for the excitation and emission, respectively, the LODs (S/N = 3) are from 0.2 nM (glutathione) to 0.8 nM (cysteine). The feasibility of this method in real samples has been evaluated by the determination of thiols in human plasma from the healthy persons and hypertensive patients with recoveries of 92–105.3%.     

Routes to halogen‐free flame‐retardant polypropylene wood plastic composites

Developing halogen‐free flame retardants with reasonably high efficiency, which thus function at limited loadings in polypropylene‐based wood/plastic composites (WPC), is still a challenge. Cost‐effective flame‐retarded WPC have been identified as a way to open the door to an interesting, broader spectrum of application in the building and transportation sectors. This work imparts a systematic comprehensive understanding and assessment of different basic routes to halogen‐free flame‐retarded WPC, taking into account economic and environmental considerations. Cheap, halogen‐free single‐component flame retardants and their multicomponent systems are investigated at reasonable filling grades of 20 wt%. The basic routes of promising synergistic multicomponent systems are discussed, and their potential and limits assessed. Optimizing the consistency of fire residue; closing the surface of inorganic‐organic residual layers; the thermal stabilization and design of the residue, eg, synergistic combination of ammonium polyphosphate and expandable graphite; and the combination of different flame‐retardant mechanisms, eg, intumescence and flame inhibition, are proposed as promising routes to boost the flame‐retardant efficiency.     

Synthesis of 2H‐Indazolo[2,1‐b]Phthalazine‐1,6,11(13H)‐Trione Derivatives Using Wet Cyanuric Chloride under Solvent‐Free Condition

A simple and facile synthesis of 2H‐indazolo[2,1‐b]phthalazine‐1,6,11(13H)‐trione derivatives has been accomplished by a three‐component condensation reaction of dimedone, aromatic aldehydes and phthalhydrazide under solvent‐free conditions in the presence of wet cyanuric chloride as a catalyst.     

Combined use of cyclofructans and an amino acid ester‐based ionic liquid for the enantioseparation of huperzine A and coumarin derivatives in CE

Cyclofructans (CFs) and their derivatives have recently been proven to be efficient chiral selectors (CSs) for the enantioseparation of several analytes in CE, HPLC, and GC. In this study, the chiral separation ability of a number of native and derivatized CFs was examined in CE. Particularly, six different CFs, with different derivatization groups and cavity sizes [native CF‐6 and CF‐7, isopropyl cyclofructan‐6 (IPCF‐6), IPCF‐7, sulfated cyclofructan‐6 (SCF‐6), and SCF‐7] were used as CSs for the enantioseparation of huperzine A, warfarin, and coumachlor. Almost all of the examined CFs, except from SCF‐6 & ‐7, demonstrated relatively low and sometimes no chiral separation ability for huperzine A. In an effort to improve both resolution and efficiency, the chiral ionic liquid D‐Alanine tert butyl ester lactate (D‐AlaC₄Lac) was added into the BGE. In most of the cases, the combination of CF with D‐AlaC₄Lac resulted in an improvement in peak efficiency and/or resolution. When CF‐6 was utilized with D‐AlaC₄Lac, a resolution of 1.4 was obtained, while the use of IPCF‐6/D‐AlaC₄Lac provided a baseline enantioseparation. Although the combination of SCF‐7 and 40 mM D‐AlaC₄Lac did not affect resolution, it dramatically increased peak efficiency from 24 000 to 117 000. In the case of warfarin and coumachlor, IPCF‐6 and IPCF‐7 proved to be the most effective CSs. It is, therefore, concluded that the size of the cavity and the CF derivatization are the key parameters for the chiral separation capability. It is also clear from this study that D‐AlaC₄Lac is necessary for improved peak efficiencies and resolutions.     

An efficient self-consistent field method for large systems of weakly interacting components

An efficient method for removing the self-consistent field (SCF) diagonalization bottleneck is proposed for systems of weakly interacting components. The method is based on the equations of the locally projected SCF for molecular interactions (SCF MI) which utilize absolutely localized nonorthogonal molecular orbitals expanded in local subsets of the atomic basis set. A generalization of direct inversion in the iterative subspace for nonorthogonal molecular orbitals is formulated to increase the rate of convergence of the SCF MI equations. Single Roothaan step perturbative corrections are developed to improve the accuracy of the SCF MI energies. The resulting energies closely reproduce the conventional SCF energy. Extensive test calculations are performed on water clusters up to several hundred molecules. Compared to conventional SCF, speedups of the order of (N/O)2 have been achieved for the diagonalization step, where N is the size of the atomic orbital basis, and O is the number of occupied molecular orbitals.     

On the use of the observation‐wise k‐fold operation in PCA cross‐validation

Cross‐validation (CV) is a common approach for determining the optimal number of components in a principal component analysis model. To guarantee the independence between model testing and calibration, the observation‐wise k‐fold operation is commonly implemented in each cross‐validation step. This operation renders the CV algorithm computationally intensive, and it is the main limitation to apply CV on very large data sets. In this paper, we carry out an empirical and theoretical investigation of the use of this operation in the element‐wise k‐fold (ekf) algorithm, the state‐of‐the‐art CV algorithm. We show that when very large data sets need to be cross‐validated and the computational time is a matter of concern, the observation‐wise k‐fold operation can be skipped. The theoretical properties of the resulting modified algorithm, referred to as column‐wise k‐fold (ckf) algorithm, are derived. Also, its performance is evaluated with several artificial and real data sets. We suggest the ckf algorithm to be a valid alternative to the standard ekf to reduce the computational time needed to cross‐validate a data set. Copyright © 2015 John Wiley & Sons, Ltd.     

Straightforward Hantzsch four‐ and three‐component condensation in the presence of triphenyl(propyl‐3‐sulfonyl)phosphoniumtrifluoromethanesulfonate {[TPPSP]OTf} as a reusable and green mild ionic liquid catalyst

Triphenyl(propyl‐3‐sulfonyl)phosphoniumtrifluoromethanesulfonate {[TPPSP]OTf} as a reusable, green and benign ionic liquid catalyst has been used in the Hantzsch four‐component (synthesis of polyhydroquinolines) and three‐component (synthesis of acridines) condensation reactions of 1,3‐diones, β‐ketoesters, aldehydes, ammonium acetate and aniline derivatives in the presence of 0.5 mol% of {[TPPSP]OTf} at room temperature under solvent‐free conditions. The new ionic liquid catalyst was fully characterized using infrared, ¹H NMR, ¹³C NMR, ³¹P NMR, ¹⁹F NMR and mass spectroscopies, and thermogravimetric and derivative thermogravimetric analyses. Additionally, the recovered catalyst can be recycled at least five times in subsequent reactions without significant loss in catalytic activity. The new synthesis technique presented offers numerous advantages of safety, mild conditions, simplicity, short reaction time, high yields and easy workup compared to the traditional synthesis method. Twenty products have been reported for the first time. Copyright © 2016 John Wiley & Sons, Ltd.