A highly efficient and ecofriendly procedure for tetrahydropyranylation of alcohols and phenols in the presence of in-situ generated I2 under heterogeneous and neutral conditions

Abstract  Molecular iodine generated in situ from Fe(NO₃)₃·9H₂O/NaI acts as a highly efficient catalyst for tetrahydropyranylation of various alcohols and phenols with 3,4-dihydro-2H-pyran in almost quantitative yields. The reaction occurs rapidly in dichloromethane at room temperature, and use of toxic molecular iodine is avoided. Graphical Abstract        

A simple and effective approach to the synthesis of rhodanine derivatives via three-component reactions in water

A facile and direct synthetic entry to rhodanine derivatives via the three-component coupling of carbon disulfide, primary amines, and acetylenic esters under neutral conditions in water is reported.     

New characterizations of fusion frames (frames of subspaces)

In this article, we give new characterizations of fusion frames, on the properties of their synthesis operators, on the behavior of fusion frames under bounded operators with closed range, and on erasures of subspaces of fusion frames. Furthermore we show that every fusion frame is the image of an orthonormal fusion basis under a bounded surjective operator.     

A novel pseudo-seven-component diastereoselective synthesis of λ-phosphanylidene bis(2,5-dioxotetrahydro-1H-pyrrole-3-carboxylates) via binucleophilic systems

The unusual 1:2 intermediate, generated by the addition of triphenylphosphine (TPP) to dialkyl acetylenedicarboxylates (DAAD) was trapped during the reaction of a Ph₃P/RN = C/DMAD binucleophilic system with TFA as an initial proton source in a pseudo-seven-component (7-CR) diastereoselective reaction to give λ⁵-phosphanylidene bis(2,5-dioxotetrahydro-1H-pyrrole-3-carboxylates) with three stereogenic centers and a phosphorane group in good yields.     

Theoretical studies on the nature and strength of an intermolecular non-covalent Te•••π interaction

ABSTRACT

DFT and MP2 calculations were used to determine the nature of non-covalent tellurium–π interactions in R₂Te???C₆H₆ (R = H, F, Cl, CH₃) and C₄H₄Te???C₆H₆ systems. The results showed that the strength of Te···π interaction follows the order F₂Te > Cl₂Te > tellurophene > H₂Te > Me₂Te. Also, the F₂X···π system complexes (X = Te or Se, π system = C₆F₆, C₆(CH₃)₆, Cr(C₆H₆)₂ and coronene) were studied for investigating the direction of charge flow in Te···π interaction. The obtained data expressed that the existence of electron withdrawing group on Te atom increases the strength of Te???π interaction while the fluorine atoms on benzene ring decrease it. The breakdown of ΔE_int in the R₂Te···C₆H₆ (R = H, F, Cl, CH₃) and C₄H₄Te···C₆H₆ systems using two dispersion corrected DFT methods showed that when the R group on divalent tellurium atom is an electron withdrawing substituent, the contribution of ΔE_elstat and ΔE_orb in total interaction energy increases and the value of ΔE_int is relatively large. The present data also showed that the intermolecular Te···π interactions are slightly stronger than corresponding Se···π interactions.     

Energy decomposition analysis of the metal-imine bond in [(CO)4M–SB] (M = Cr,Mo, W; SB: RHCN–CH2CH2–NCHR)

The electronic and molecular structures of the metal-Schiff base complexes [(CO)₄M–SB] (M: Cr, Mo, W; SB: RHCN–CH₂CH₂–NCHR, R = C₆H₅, C₆F₅, Ortho-, Meta- and Para-XC₆H₄ (X = F, Cl, Br,CH₃)) have been investigated at the DFT level using the exchange correlation functional BP86. The nature of the TM?Schiff base interactions was analyzed with charge and energy decomposition methods. The octahedral equilibrium geometries have C_2v symmetry. The (CO)₄M–SB bond dissociation energies vary little for different substituents R. The calculated values indicate rather strong bonds which exhibit the trend for the different metals M = Mo (D_e = 59.8–65.4 kcal/mol) < Cr (D_e = 62.3–67.8 kcal/mol) < W (D_e = 69.9–75.8 kcal/mol). The energy decomposition analysis suggests that the (CO)₄M–SB attractive interactions come mainly from electrostatic attraction which provide ～60% to ?E_int while ～40% come from orbital interactions. The latter term arises mainly (～70%) through (CO)₄M ← SB σ donation from the nitrogen lone-pair orbitals while a much smaller part (～20%) comes from (CO)₄M→SB π backdonation. The transition metals carry large negative partial charges between ?2.3 e for M = Cr and ?1.1e for M = W.     

Proposal for inverting the quantum cloning of photons

We propose an experiment where a photon is first cloned by stimulated parametric down-conversion, making many (imperfect) copies, and then the cloning transformation is inverted, regenerating the original photon while destroying the copies. Focusing on the case where the initial photon is entangled with another photon, we study the conditions under which entanglement can be proven in the final state. The proposed experiment would provide a clear demonstration that quantum information is preserved in quantum cloning. It would furthermore allow a definitive experimental proof for micro-macro entanglement in the intermediate multiphoton state, which is still an outstanding challenge. Finally, it might provide a quantum detection technique for small differences in transmission (e.g., in biological samples), whose sensitivity scales better with the number of photons used than a classical transmission measurement.     

Construction of stable multivariate calibration models using unsupervised segmented principal component regression

In multivariate spectral calibration by principal component regression (PCR), the principal components (PCs) are calculated from the response data measured at all employed instrument channels; however some channels are redundant and their responses do not possess useful information. Thus, the extracted PCs possess mixed information from both useful and redundant channels. In this work, we propose a segmentation approach based on unsupervised pattern recognition to identify the most informative spectral region and then to construct a stable multivariate calibration model by PCR. In this method, the instrument channels are clustered into different segments via Kohonen self‐organization map. The spectral data of each segment are then subjected to PCA and the derived PCs are used as input variables for an inverse least square (ILS) regression model employing stepwise selection of the informative PCs. The proposed method was evaluated by the analysis of four simulated and six experimental data sets. It was found that our proposed method can model the above data sets with prediction errors lower than conventional partial least squares (PLS) and PCR methods. In addition, the prediction ability of our method was better than the previously reported models for these data sets. Copyright © 2011 John Wiley & Sons, Ltd.     

Stability of preserving lattice cubic functional equation in Menger probabilistic normed Riesz spaces

The aim of this paper is to investigate Hyers–Ulam–Rassias stability of preserving lattice functional equation in various spaces. First, we prove stability of generalized preserving lattice functional equation in Banach lattices. Next, we show stability of preserving lattice cubic functional equation in Menger probabilistic normed Riesz spaces.