Synthesis,characterization and antifungal testing of 3,4-dihydropyrimidin-2(1H)-(thio)ones containing boronic acids and boronate esters

The addition of formylphenylboronic acid derivatives to thiourea and ethyl acetoacetate proceeds in the presence of an additional Lewis acid catalyst to give the corresponding 3,4-dihydropyrimidin-2(1H)-(thio)ones (Biginelli products) in moderate yield. Compounds were tested for antifungal activity against pure cultures of Aspergillus niger, Aspergillus flavus, Candida albicans and Saccharomyces cerevisiae but, unfortunately, none showed any appreciable activity.      

Saturation of transverse energy per charged hadron and freeze-out criteria in heavy-ion collisions

The effective (non-universal) nature of Sivers function reflects the process dependence of the imaginary phase required for T-odd Single Spin asymmetry. The explicit account for the phase allows to relate T-odd and T-even Spin asymmetries. The soft-gluon twist 3 contributions to single-spin asymmetries (SSA) in hard processes may be expressed in the form of effective T-odd Sivers distributions, whose signs and scales are modified by process-dependent colour factors. The Sivers mechanism is applied at large transverse momenta and the emission of balancing gluons provide the colour flow explaining this factor.     

Synthesis and molecular structure of 4,4,5,5-tetramethyl-2-(1-(phenylsulfonyl)propan-2-yl)-1,3,2-dioxaborolane

The compound 4,4,5,5-tetramethyl-2-(1-(phenylsulfonyl)propan-2-yl)-1,3,2-dioxabo- rolane has been prepared by the rhodium catalyzed hydroboration of allyl phenyl sulfone and characterized by a single crystal X-ray diffraction study. The title compound crystallized in the monoclinic space group P2₁/c, with cell parameters a=16.0728(8) ?, b=9.8884(5) ?, and c=10.1926(5) ?, β=92.067(1)°, Z=4, and V=1618.90(14) ?³. The structure was solved by direct methods and refined to a final R=0.0449 for 3627 reflections with I>2σ(I). No significant intramolecular or intermolecular interaction is observed with the Lewis acidic boron atom.     

Recent applications of THERMUS

Some of the most recent applications of the statistical-thermal model package, THERMUS, are reviewed. These applications focus on fluctuation and correlation observables in an ideal particle and anti-particle gas in limited momentum space segments, as well as in a hadron resonance gas. In the case of the latter, a Monte Carlo event generator, utilising THERMUS functionality and assuming thermal production of hadrons, is discussed. The system under consideration is sampled grand canonically in the Boltzmann approximation. A re-weighting scheme is then introduced to account for conservation of charges (baryon number, strangeness, electric charge) and energy and momentum, effectively allowing for extrapolation of grand canonical results to the micro canonical limit. The approach utilised in this and other applications suggests improvements to existing THERMUS calculations.     

Synthesis,structure, and antifungal activity of dihydropyridones containing boronate esters

We have prepared a series of novel 2,3‐dihydro‐4‐pyridones containing boronate esters using the aza Diels–Alder reaction with Danishefsky's diene and imines derived from formylphenylboronic acids. This reaction can be carried out in moderate to high yields using Yb(OTf)₃ as a Lewis acid catalyst. Two new boron compounds exhibited moderate antifungal activity (at 100 μg disk⁻¹) using Amphotericin B as a control. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:56–63, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20512     

Antioxidant activity and total phenolic content of aqueous and methanolic extracts of Jordanian plants: an ICBG project

As part of an International Cooperative Biodiversity Groups (ICBG) program to study Jordan's biodiversity, the relative levels of antioxidant activity and the total phenolic content of aqueous and methanolic extracts of a total of 95 plant species, all of Jordanian origin and those collected at random, have been measured. The total phenolic content of aqueous and methanolic extracts of the investigated plant species ranged from 4.4 to 78.3 mg and from 2.1 to 52.8 mg gallic acid equivalents g(-1) dry weight, respectively, while the total antioxidant capacity ranged from 20.0 to 916.7 and from 15.1 to 915.6 micromol Trolox equivalents g(-1) dry weight, respectively. Based on this collection, approximately 5% of assayed plants showed high levels of antioxidant activity. There was a significant linear correlation between antioxidant activity and total phenolic content for aqueous and methanolic extracts, suggesting that phenolic compounds were the predominant antioxidant components in the investigated plant species. Interestingly, a few of the collected plants had high-antioxidant activity yet "low" phenolic content includes Ceratonia siliqua and Viscum cruciatum. These plants may serve as sources of antioxidants with new chemotypes.     

Cationic zinc complexes: a new class of catalyst for living lactide polymerization at ambient temperature

Cationic zinc complexes of a bis(phosphinimine) pincer ligand have been prepared. Methylzinc and zinc-lactate complexes have been structurally characterized, and the latter is the first cationic metal complex to promote coordination-insertion polymerization of lactide at ambient temperature. This novel catalyst system is remarkably active and also exhibits living character. A detailed investigation of the kinetics and mechanism of the polymerization process has been undertaken.     

Self-assembly of coordination polymers: evidence for dynamic exchange between oligomers in solution and the isolation of a homochiral decagold(I) oligomer

Reactions of the precursor molecules [Au2(mu-BINAP)(O2CCF3)2], 1a, racemic BINAP, 1b, S-BINAP (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) with the easily exchanged linear bis(pyridine) ligand 1,2-trans-bis(4-pyridyl)ethylene (bipyen) gave the polymeric complex [{Au2(mu-R-BINAP)0.5(mu-S-BINAP)0.5(mu-bipyen)}n](CF3CO2)2n, 2a, but either the polymer [{Au2(mu-S-BINAP)(mu-bipyen)}n](CF3CO2)2n, 2b, or the remarkable oligomeric [Au10(mu-S-BINAP)5(mu-bipyen)4(kappa1-bipyen)2](CF3CO2)10, 3, respectively. The type of oligomer 3 is a missing link in the ring-opening polymerization of macrocyclic coordination compounds.     

A computational characterization of the hydrogen-bonding and stacking interactions of hypoxanthine

The hydrogen-bonding and stacking interactions of hypoxanthine, a potential universal nucleobase, were calculated using a variety of methodologies (CCSD(T), MP2, B3LYP, PWB6K, AMBER). All methods predict that the hydrogen-bonding interaction in the hypoxanthine-cytosine pair is approximately 25 kJ mol(-1) stronger than that in the other dimers. Although the calculations support suggestions from experiments that hypoxanthine preferentially binds with cytosine, the trend in the calculated hydrogen-bond strengths for the remaining natural nucleobases do not show a strong correlation with the experimentally predicted binding preferences. However, our calculations suggest that the stacking interactions of hypoxanthine are similar in magnitude to the hydrogen-bonding interactions at all levels of theory (with the exception of B3LYP, which incorrectly predicts stacked dimers to be unstable). Therefore, stacking interactions should also be considered when analyzing the stability of DNA helices containing hypoxanthine and the use of larger models that account for both hydrogen-bonding and stacking within DNA duplexes will likely result in better agreement with experimental observations. For the majority of the dimers, PWB6K and AMBER provide reasonable binding strengths at reduced computational costs, and therefore will be useful techniques for considering larger models.