Copper(I) iodide–catalyzed amidation of phenylboronic acids/aryl bromides using 4-dimethylaminopyridine as ligand

An efficient one-pot synthesis of N-arylbenzamide is described via reaction of phenylboronic acid/aryl bromide with benzamide in the presence of CuI (5 mol%) as catalyst, 4-dimethylaminopyridine (20 mol%) as the ligand, and Cs₂CO₃ (2 mmol) as the base. This protocol was applied to synthesize a small library of N-arylbenzamide in high yields.     

Chemoenzymatic synthesis of duloxetine and its enantiomer: lipase-catalyzed resolution of 3-hydroxy-3-(2-thienyl) propanenitrile

An efficient and facile chemoenzymatic synthesis of duloxetine by lipase mediated resolution of 3-hydroxy-3-(2-thienyl)propanenitrile has been achieved. This process also describes an enantioconvergent synthesis of duloxetine via a Mitsunobu reaction.     

Simple and Efficient One-Pot Synthesis of 2-Substituted Benzimidazoles from θ-Diaminoarene and Aryl Aldehydes

An easy and efficient one-pot condensation method for the synthesis of substituted benzimidazoles from θ-phenylenediamines with aryl aldehydes using urea hydrogen peroxide (UHP) and I₂ in dimethylsulfoxide (DMSO) provides wide substrate scope with good to excellent yields and simple and quick isolation of the products.     

Determination of Ranolazine in Tablet Formulations by High-Performance Thin-Layer Chromatography—Mass Spectrometry Using Reflectance Scanning Densitometry

JPC – Journal of Planar Chromatography – Modern TLC - A new quantitative densitometric high-performance thin-layer chromatographic (HPTLC) method was developed and validated for the...     

Thermal analysis of spider silk inspired di-block copolymers in the glass transition region by TMDSC

We used advanced thermal analysis methods to characterize a new family of A-B di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk. Using temperature modulated differential scanning calorimetry with a thermal cycling method and thermogravimetry, we captured the effect of bound water acting as a plasticizer for spider silk-like biopolymer films which had been cast from water solution and then dried. A low glass transition because of bound water removal was observed in the first heating cycle, after which, a shift of glass transition was observed in A-block film due to crystallization and annealing, and in BA film due to annealing. No shift of glass transition after bound water removal was observed in B-block film. The reversing heat capacities, C _p, for temperatures below and above the glass transition were measured and compared to the calculated values. The solid state heat capacity was modeled below T _g, based on the vibrational motions of the constituent poly(amino acid)s, heat capacities of which are known from the ATHAS Data Bank. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this model can serve as a standard method to predict the solid state C _p for other biologically inspired block-copolymers. We also calculated the liquid state heat capacities of the 100% amorphous biopolymer at T _g, and this predicted value can be use to determined the crystallinity of protein-based materials.     

Thin film assembly of spider silk-like block copolymers

We report the self-assembly of monolayers of spider silk-like block copolymers. Langmuir isotherms were obtained for a series of bioengineered variants of the spider silks, and stable monolayers were generated. Langmuir-Blodgett films were prepared by transferring the monolayers onto silica substrates and were subsequently analyzed by atomic force microscopy (AFM). Static contact angle measurements were performed to characterize interactions across the interface (thin film, water, air), and molecular modeling was used to predict 3D conformation of spider silk-like block copolymers. The influence of molecular architecture and volume fraction of the proteins on the self-assembly process was assessed. At high surface pressure, spider silk-like block copolymers with minimal hydrophobic block (f(A) = 12%) formed oblate structures, whereas block copolymer with a 6-fold larger hydrophobic domain (f(A) = 46%) formed prolate structures. The varied morphologies obtained with increased hydrophobicity offer new options for biomaterials for coatings and related options. The design and use of bioengineered protein block copolymers assembled at air-water interfaces provides a promising approach to compare 2D microstructures and molecular architectures of these amphiphiles, leading to more rationale designs for a range of nanoengineered biomaterial needs as well as providing a basis of comparison to more traditional synthetic block copolymer systems.     

Millimeter wave dispersion in ethyl chloride

Dispersion of millimeter waves due to ethyl chloride in the range ν=1·34 cm^?1 to 1·44 cm^?1 is computed by means of quantum mechanical formulas. It is found that dispersion is due to (i) contribution of sixR branch rotational lines in the region considered, (ii) contribution ofR branch lines away from the region and (iii) the contribution ofQ branch lines at zero wavenumber. The maximum variation in the susceptibility is 1·9 × 10^?5 and occurs at ν=1·39 cm^?1 due to combined contribution of transitions at 1·3878 cm^?1, 1·3902 cm^?1 and 1·3927 cm^?1.     

The dielectric behaviour of acetaldehyde vapour at 9000 MC/sec.

Complex dielectric constant of the acetaldehyde vapour and its dependence on pressure and temperature has been studied in the microwave region at 9000 MC/sec. The electric susceptibility is found to vary linearly with pressure in the moderate pressure region. The absorption coefficient varies approximately as P² showing convexity towards pressure axis. The temperature dependence law as obtained by absorption coefficient measurements at temperatures between ?8° to 50° C follows T^?3 law as expected onAnderson's orMargenau's expressions for\(\overline {\Delta v}\).     

A new chemoenzymatic Baylis-Hillman approach for the synthesis of enantiomerically enriched umbelactones

An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched umbelactones is described utilizing a lipase-mediated resolution protocol, Baylis-Hillman reaction and ring closing metathesis as key steps. The lipase-resolution is carried out using several lipases from various sources in different solvents to afford the required intermediate 8 in good yield and high enantioselectivity.     

Chemoenzymatic synthesis of enantiomerically enriched kavalactones

Lipase-mediated kinetic resolution of methyl-3-hydroxy-5-phenylpentanoate and (6E)-ethyl 5-hydroxy-3-oxo-7-phenylhept-6-enoate is described in high enantiomeric excess and good yields. The effect of different lipases in different solvents has been screened using different acylating agents. This protocol has been extended for the preparation of enantiomerically pure biologically important kavalactones.