ABSTRACT Detailed DFT studies provide an in-depth mechanistic understanding for the use of chiral amide-based ammonium ylides in epoxidation reactions. It is shown that the used chiral auxiliary efficiently shields one face of the ylide, which thus results in an extraordinarily high stereoselectivity giving only one trans-isomer with perfect control of the absolute configuration. GRAPHICAL AB...

OBJECTIVE To determine the effects of 2 conjugated linoleic acid (CLA) isomers (cis-9, trans-11 and trans-10, cis-12) on synthesis of prostaglandin (PG) E(2) and F(2α) and expression of prostaglandin H synthase-2 (PGHS-2) of adult and fetal bovine endometrial epithelial cells in vitro. SAMPLE Primary cultures of endometrial epithelial cells obtained from 4 adult cows and 4 fetal bovine carcas...

The retinal epithelium plays an important role in the storage and metabolism of retinoids in the eye. Studies were conducted to examine the enzymatic hydrolysis of retinyl esters by human retinal epithelial cells. Homogenates prepared from these cells were found to hydrolyze both the 11-cis- and all-trans-isomers of retinyl palmitate. Retinyl ester hydrolysis was time-, protein-, and pH-depende...

A binuclear tungsten(0) complex with an asymmetric bridging 1,2-diphosphole ligand was prepared by the photolysis of tungsten hexacarbonyl in presence 1-isopropyl-2-phenyl-1,2,5,6-tetrahydroacenaphtho [5,6-cd][1,2]diphosphole. The 1 characterized high resolution mass spectrometry, multinuclear NMR spectroscopy (1H, 13C, 31P), and elemental microanalysis. structure trans isomer resolved single c...

Olefination of aromatic and aliphatic aldehydes with ethyl diazoacetate was achieved in excellent yields with triphenylphosphine and catalytic amounts of iron(II) meso-tetra(p-tolyl)porphyrin. The reaction conditions are mild and the process is efficient and highly selective (>90%) for the synthesis of the trans-olefin isomer. Results of mechanistic studies are discussed.

Cis and trans-Cr-N(2) complexes supported by the diphosphine ligand P(Ph)(2)N(Bn)(2) have been prepared. Positioned pendant amines in the second coordination sphere influence the thermodynamically preferred geometric isomer. Electronic structure calculations indicate negligible Cr-N(2) back-bonding; rather, electronic polarization of N(2) ligand is thought to stabilize Cr-N(2) binding.

The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer, trans-8, cis-10 (t8, c10)-CLA, in the form of an equimolar mixture with the cis-9, trans-11 (c9, t11) isomer, on body weight and body composition, circ...

The possibility was examined that the carbamoylating activity of some chloroethylnitrosoureas could interfere with the activity of normal human cells to survive treatment with these drugs; 1-(2-chloroethyl)-3-(trans-4-hydroxycyclohexyl)-1-nitrosourea, which has strong carbamoylating activity, inhibited the rejoining of drug or X-ray-induced DNA strand breaks in IMR-90 cells, whereas the noncarb...

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of octadecadienoic acid [linoleic acid (LA), 18:2n-6] commonly found in beef, lamb and dairy products. The most abundant isomer of CLA in nature is the cis-9, trans-11 (c9t11) isomer. Commercially available CLA is usually a 1:1 mixture of c9t11 and trans-10, cis-12 (t10c12) isomers with other isomers as minor compon...