Direct asymmetric Michael addition of ketones to chalcones catalyzed by a hydroxyphthalimide derived triazole–pyrrolidine

An efficient protocol for the enantioselective Michael additions of ketones to chalcones catalyzed by a hydroxyphthalimide linked triazole–pyrrolidine derivative has been developed. The corresponding products, 1,5-dicarbonyl compounds, were obtained in good yields with high levels of stereoselectivities under mild reaction conditions employing benzoic acid as an additive.     

The catalytic effect of Ag/CNTs nanocomposite on the ignition reaction of Mg/KNO3 pyrotechnic by determination of the kinetic triplet

Journal of Thermal Analysis and Calorimetry - The ignition reaction of Mg/KNO3 was improved with addition of Ag/CNTs nanocomposite as catalyst. The nanoparticles of Ag(0) was deposited on the...     

One-pot synthesis of 1, 3-thiazolidin-4-one using Bi(SCH2COOH)3 as catalyst

A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH₂COOH）₃ as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.The efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.     

On the natural convection of nanofluids in diverse shapes of enclosures: an exhaustive review

Journal of Thermal Analysis and Calorimetry - The ultimate goal of the present review paper is to summarize and discuss the findings of the most recently published literature on natural convection...     

Physical basis for membrane-charge selectivity of cationic antimicrobial peptides

Antimicrobial peptides are known to selectively disrupt (highly charged) microbial membranes by asymmetrical incorporation into the outer layers. We present a physical basis for membrane-charge selectivity of cationic antimicrobial peptides. In particular, we provide a clear picture of how peptide-charge Q influences the asymmetrical insertion--one salient feature is the existence of an optimal peptide charge, at which selective insertion is optimized. Our results suggest that large Q is required for antimicrobial selectivity, consistent with experiments.     

Daturacin, a new withanolide from Datura innoxia

The methanolic extract of the aerial parts of Datura innoxia afforded a new withanolide, daturacin, the structure of which was elucidated as (20R, 22S)-21,24-epoxy-1,6-dioxo-14alpha-methoxy-5beta-witha-2,25(27)-dienolide (1) by an analysis of the spectroscopic data, including extensive NMR experiments.     

Isolation and structure determination of a benzofuran and a bis-nor-isoprenoid from Aspergillus niger grown on the water soluble fraction of Morinda citrifolia Linn. leaves

The leaves of Morinda citrifolia, Linn. afforded a new benzofuran and a bis-nor-isoprenoid, blumenol C, hitherto unreported from this source. The structures of these have been elucidated as 5-benzofuran carboxylic acid-6-formyl methyl ester (1) and 4-(3'(R)-hydroxybutyl)-3,5,5, trimethyl-cyclohex-2-en-1-one (2) respectively through spectroscopic studies. The NMR data (including 1D, 2D techniques) and stereochemistry at C-3' of Compound 2 is also being reported for the first time.     

Selective monotetrahydropyranylation of symmetrical diols using P_20_5/Si0_2 under solvent-free conditions and their depyranylation

Selective protection of one of the hydroxyl group in 1,n-symmetrical diols is achieved by P_2O_2/SiO_2-catalyzed reaction of the diol with dihydropyran under solvent-free conditions at room temperature.This selective protection is simple and it occurred under economically cheap conditions in high yield.The deprotected diol is simply obtained by refluxing of this compound in methanol using the same catalyst without any byproduct formation or additional purifications.     

Conversion of iminoacyl quinolinylpalladium (II) complexes into novel oxo‐pyrrolo[3,4‐b] quinolines via depalladation reactions

Oxidative addition reactions of quinolines 1a , b with Pd(dba)₂ in the presence of PPh₃ (1:2) in acetone gave dinuclear palladium complexes [Pd(C,N‐2‐C₉ H₄N‐CHO‐3‐R‐6)Cl(PPh₃)]₂ [(R = H ( 2a ), R = OMe ( 2b ), which were reacted with isocyanide XyNC (Xy = 2,6‐Me₂C₆H₃) to give novel iminoacyl quinolinylpalladium complexes 3a , b in good yields (81 and 77%). Cyclopalladated complexes 3a , b were also obtained in low yields (39 and 33.5%) via one‐pot reaction of 1a , b with isonitrile XyNC:Pd(dba)₂ (4:1). The reaction of 3a , b with Tl(TfO) (TfO = triflate, CF₃SO₃) in the presence of H₂O or EtOH causes depalladation reactions of complexes to provide the corresponding organic compounds 4a , b , 5a , b and 6a , b in yields of 41, 27 and 18 ? 19%, respectively. The products were characterized by satisfactory elemental analyses and spectral studies (IR, ¹H, ¹³C and ³¹P NMR). The crystal structures 2a , 3a and 3b were determined by X‐ray diffraction studies. Copyright © 2008 John Wiley & Sons, Ltd.