An efficient electrophilic N-amination utilizing in situ generated chloramine under phase transfer conditions

An efficient, one-pot, phase transfer N-amination technology was developed. The protocol utilizes chloramine, an inexpensive and safe electrophilic aminating agent potentially viable for commercial manufacturing.     

Cu(I) catalyst in DMF: an efficient catalytic system for the synthesis of furans from 2-(1-alkynyl)-2-alken-1-ones

The cyclization of 2-(1-alkynyl)-2-alken-1-ones 1 proceeded very smoothly in the presence of alcohols 2 with a catalytic amount of Cu(I)Br in DMF at 80 degrees C, leading to the formation of highly substituted furans 3. The catalytic system reported herein is easy to handle, compared to the previously known system wherein the reaction between 1 and 2 needed to use moisture sensitive gold(III) chloride.     

Bounds for the generalized Marcum function of the second kind

The Ramanujan Journal - This paper provides elementary proofs for several types of congruences involving multipartitions and self-convolutions of the divisor function. Our computations use...     

Optimal allocation of replicas in parallel tempering simulations

We have studied the efficiency of parallel tempering simulations for a variety of systems including a coarse-grained protein, an atomistic model polypeptide, and the Lennard-Jones fluid. A scheme is proposed for the optimal allocation of temperatures in these simulations. The method is compared to the existing empirical approaches used for this purpose. Accuracy associated with the computed thermodynamic quantities such as specific heat is also computed and their dependence on the trial-exchange acceptance rate is reported.     

Constrained photophysics of 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine in micellar environments: a spectrofluorometric study

Photophysical properties of 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ) have been studied in different aqueous micellar environments using steady-state and time-resolved emission spectroscopy. The charge transfer (CT) fluorescence exhibits appreciable hypsochromic shift, along with an enhancement in the fluorescence intensity in all the micellar media. This is associated with an increase in the fluorescence anisotropy (r), which suggests that the fluorophore molecule experiences motionally restricted environments upon binding with the micelles. Fluorescence spectral position and fluorescence quenching studies suggest that the fluorescing moiety does not penetrate into the core of the micellar units; rather it binds at the micelle-water interfacial region. The binding constant and free energy change during probe-micelle binding have been evaluated from relevant fluorescence data. Light has been thrown on the mode of action of urea on micelle bound probes. The results are interpreted in terms of the model that urea displaces water molecules from the micellar interface and the consequent destabilization leads to the expulsion of the probe molecules from the interfacial region. Polarity and viscosity of the microenvironments around the probe have been determined in the micellar systems.     

ZrOCl2·8H2O: An Efficient Catalyst for One-Pot Synthesis of α-Amino Phosphonates Under Solvent-Free Conditions

A highly efficient protocol has been developed for the three-component reaction of an amine, an aldehyde, and diethyl phopshite catalyzed by ZrOCl₂·8H₂O, an environmentally friendly catalyst, at ambient temperature. The catalyst exhibited remarkable activity and tolerated a wide variety of functional groups, providing the desired amino phosphonates in excellent yields under solvent-free conditions. Alternatively, the reaction rate can be significantly enhanced by carrying out the reaction in a monomode microwave reactor as a promoter.     

Rapid assessment of drug response in cancer cells using microwell array and molecular imaging

Selection of personalized chemotherapy regimen for individual patients has significant potential to improve chemotherapy efficacy and to reduce the deleterious effects of ineffective chemotherapy drugs. In this study, a rapid and high-throughput in vitro drug response assay was developed using a combination of microwell array and molecular imaging. The microwell array provided high-throughput analysis of drug response, which was quantified based on the reduction in intracellular uptake (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose) (2-NBDG). Using this synergistic approach, the drug response measurement was completed within 4 h, and only a couple thousand cells were needed for quantification. The broader application of this microwell molecular imaging approach was demonstrated by evaluating the drug response of two cancer cell lines, cervical (HeLa) and bladder (5637) cancer cells, to two distinct classes of chemotherapy drugs (cisplatin and paclitaxel). This approach did not require an extended cell culturing period, and the quantification of cellular drug response was 4–16 times faster compared with other cell-microarray drug response studies. Moreover, this molecular imaging approach had comparable sensitivity to traditional cell viability assays, i.e., the MTT assay and propidium iodide labeling of cellular nuclei;and similar throughput results as flow cytometry using only 1,000–2,000 cells. Given the simplicity and robustness of this microwell molecular imaging approach, it is anticipated that the assay can be adapted to quantify drug responses in a wide range of cancer cells and drugs and translated to clinical settings for a rapid in vitro drug response using clinically isolated samples.      

N-Chlorosuccinimide (NCS)–N,N-dimethylformamide (DMF), a reagent for the oxidation of benzylic alcohols to aldehydes and ketones

Molecular Diversity - The oxidation of benzylic alcohol to corresponding aldehyde and ketone using N-chlorosuccinimide (NCS)–N,N-dimethylformamide (DMF) has been described. This method gives...     

Synthesis,characterization and biological activity of mixed ligands complexes of quinolin-8-ol and substituted chromones with Mn(II), Co(II), Ni(II) and Cu(II) metal ions

Research on Chemical Intermediates - The mixed ligand complexes were synthesized using quinolin-8-ol and substituted chromone derivative with transition metals like Mn(II), Cu(II), Ni(II) and...