New ligands and structural insights into the catalytic asymmetric addition of organozinc reagents to ketones

The catalytic asymmetric addition of alkyl groups to ketones has received considerable attention. Outlined herein is the synthesis of two new ligands based on the C₂-symmetric 11,12-diamino-9,10-dihydro-9,10-ethanoanthracene. The scope of the new ligands has been evaluated in the catalytic asymmetric addition of diethylzinc to a variety of ketones. Enantioselectivities as high as 99% have been achieved. The structures of two of these ligands have been determined by X-ray crystallography and are compared with related structures. Additionally, the structure of a titanium complex bound to a bis(sulfonamide) diol ligand is reported.     

Morita Invariance for Infinitesimal Deformations

Algebras and Representation Theory - Let A and B be two Morita equivalent finite dimensional associative algebras over a field ��. It is well known that Hochschild cohomology is...     

Polyvinyl Alcohol–Pectin Cryogel Films for Controlled Release of Enrofloxacin

The release of enrofloxacin entrapped in polyvinyl alcohol (PVA) cryogel at pH?5.5 showed a first-order kinetic, releasing 69.7% of the antibiotic after 4.5?h at 37?°C. In order to slow down the fluoroquinolone release rate, high-methoxylated pectin was added into the cryogel (PVA?CP). A film containing 1.0% (w/v) HM pectin and 5.0???g/ml enrofloxacin released only 3.7% of the antibiotic after 4.5?h. Since the FTIR spectrum showed that most of the interactions between PVA?CP matrix and enrofloxacin were due to polar groups (carboxylate and amine), a two-layer film system was designed to modulate the releasing rate of the drug. The top film equilibrated with 0.75 or 1.5?M NaCl release up to 41.9% and 89.0% of the enrofloxacin in 4?h, respectively. The release rate of enrofloxacin was found dependent on NaCl concentration in the upper gel layer. The two-layer cryogel system showed attractive features for transcutaneous antibiotic delivery.     

Gerstenhaber Algebra Structure on the Hochschild Cohomology of Quadratic String Algebras

We describe the Gerstenhaber algebra structure on the Hochschild cohomology HH^?(A) when A is a quadratic string algebra. First we compute the Hochschild cohomology groups using Barzdell’s resolution and we describe generators of these groups. Then we construct comparison morphisms between the bar resolution and Bardzell’s resolution in order to get formulae for the cup product and the Lie bracket. We find conditions on the bound quiver associated to string algebras in order to get non-trivial structures.     

Reversible and Irreversible Tracer Dispersion in an Oscillating Flow Inside a Model Rough Fracture

We study the mixing dynamics of a dyed and a clear miscible fluid by an oscillating flow inside an Hele-Shaw cell with randomly distributed circular obstacles. A transparent setup allows us to analyze the distribution of the two fluids and the reversible and irreversible mixing components. At the lower Péclet numbers Pe (based on the averaged absolute fluid velocity), geometrical dispersion due to the disordered flow field between the obstacles is dominant: the corresponding dispersivity is constant with Pe and, at constant Pe, increases with the amplitude of the oscillations and is negligible at small ones. Compared to echo dispersion with only one injection–suction cycle, oscillating flows are shown to provide additional information when the number of oscillations and, as a result, the distance of transverse mixing are varied. Geometrical dispersion is dominant up to a limiting Pe increasing with the amplitude. At higher \({\textit{Pe}}'{\textit{s}}\), the results are similar to those of Taylor dispersion in cells with smooth walls.     

β-Caryophyllene: A Therapeutic Alternative for Intestinal Barrier Dysfunction Caused by Obesity

Obesity is an excessive accumulation of fat that exacerbates the metabolic and inflammatory processes. Studies associate these processes with conditions and dysregulation in the intestinal tract, increased concentrations of lipopolysaccharides (LPSs) in the blood, differences in the abundance of intestinal microbiota, and the production of secondary metabolites such as short-chain fatty acids. β-Caryophyllene (BCP) is a natural sesquiterpene with anti-inflammatory properties and with the potential purpose of fighting metabolic diseases. A diet-induced obesity model was performed in 16-week-old C57BL/6 mice administered with BCP [50 mg/kg]. A reduction in the expression of Claudin-1 was observed in the group with a high-fat diet (HFD), which was caused by the administration of BCP; besides BCP, the phyla Akkermansia and Bacteroidetes decreased between the groups with a standard diet (STD) vs. HFD. Nevertheless, the use of BCP in the STD increased the expression of these phyla with respect to fatty acids; a similar effect was observed, in the HFD group that had a decreasing concentration that was restored with the use of BCP. The levels of endotoxemia and serum leptin increased in the HFD group, while in the HFD + BCP group, similar values were found to those of the STD group, attributing the ability to reduce these in conditions of obesity.     

Asymmetric addition of diethylzinc to benzaldehyde catalyzed by novel chiral C2-symmetric tetrakis(sulfonamide)–titanium(IV) complexes

A series of chiral C₂-symmetric tetrakis(sulfonamides) 3a–f, 4a–f were prepared and employed as ligands for titanium(IV) complexes in the asymmetric addition of diethylzinc to benzaldehyde. The chiral secondary alcohols were obtained in high yields and in moderate enantioselectivities.     

Diazapolycyclic compounds. XXVII. On the selective hydrogenation of benzo[g]phthalazine-1,4-dione and 5-methoxybenzo[g]phthalazine-1,4-dione adducts

A number of diazapolycyclic structures obtained by cycloaddition reaction of benzo[g]phthalazine-1,4-dione with several 1,3-dienes have been catalytically hydrogenated on palladium over charcoal. In a first step the double bond formed in the cycloaddition was reduced, except in the case of tetrasubstitution. The use of longer reaction times led to the selective reduction of the terminal aromatic rings, although the presence of the 5-methoxy substituent favored tetrahydropyridazine ring opening and prevented aromatic ring reduction. The stereochemical features of new compounds obtained are commented on the basis of X-ray and nmr data.     

Hochschild cohomology of triangular string algebras and its ring structure

We compute the Hochschild cohomology groups HH^?(A)${\mathrm{HH}}^{?}(A)$ in case A is a triangular string algebra, and show that its ring structure is trivial.