A general preparation of pyridines and pyridones via the annulation of ketones and esters

A general preparation of pyridines 4a-f from stabilized ketones 3a-c and aryl ketones 3d-f is described. The annulation of stabilized esters 3g,h gives access to the corresponding 2-pyridones 4g,h. The annulation reactions proceed in fair to excellent yields (46-87%) with vinamidinium hexafluorophosphate salts 2a-d containing electron-withdrawing groups at the beta-position. The mechanism of the reaction was investigated by NMR and proceeds through the formation of a dienaminone intermediate.     

Transitive Spaces of Operators

We investigate algebraic and topological transitivity and, more generally, k-transitivity for linear spaces of operators. In finite dimensions, we determine minimal dimensions of k-transitive spaces for every k, and find relations between the degree of transitivity of a product or tensor product on the one hand and those of the factors on the other. We present counterexamples to some natural conjectures. Some infinite dimensional analogues are discussed. A simple proof is given of Arveson’s result on the weak-operator density of transitive spaces that are masa bimodules. Authors partially supported by NSERC grants.     

Semi-synthesis of a HGF/SF kringle one (K1) domain scaffold generates a potent in vivo MET receptor agonist

The development of MET receptor agonists is an important goal in regenerative medicine, but is limited by the complexity and incomplete understanding of its interaction with HGF/SF (Hepatocyte Growth Factor/Scatter Factor). NK1 is a natural occurring agonist comprising the N-terminal (N) and the first kringle (K1) domains of HGF/SF. In the presence of heparin, NK1 can self-associate into a “head to tail” dimer which is considered as the minimal structural module able to trigger MET dimerization and activation whereas isolated K1 and N domains showed a weak or a complete lack of agonistic activity respectively. Starting from these structural and biological observations, we investigated whether it was possible to recapitulate the biological properties of NK1 using a new molecular architecture of isolated N or K1 domains. Therefore, we engineered multivalent N or K1 scaffolds by combining synthetic and homogeneous site-specifically biotinylated N and K1 domains (NB and K1B) and streptavidin (S). NB alone or in complex failed to activate MET signaling and to trigger cellular phenotypes. Importantly and to the contrary of K1B alone, the semi-synthetic K1B/S complex mimicked NK1 MET agonist activity in cell scattering, morphogenesis and survival phenotypic assays. Impressively, K1B/S complex stimulated in vivo angiogenesis and, when injected in mice, protected the liver against fulminant hepatitis in a MET dependent manner whereas NK1 and HGF were substantially less potent. These data reveal that without N domain, proper multimerization of K1 domain is a promising strategy for the rational design of powerful MET agonists.     

Onset of Rayleigh-Bénard convection in a ternary liquid system and the Onsager law with generalized thermal diffusion

For the ternary system isopropanol-ethanol-water, a model was proposed to estimate the cross diffusion coefficients from measurements of the critical parameters for the onset of Rayleigh-Bénard convection, together with the consideration of the reciprocity laws of Onsager. Among the three forms of the chemical potentials used, not a single chemical potential was found to provide a correlation between the Onsager laws and the experimental data. The present study shows that consideration of a generalized thermal diffusion term taking account of all components is adequate to estimate quantitative values of the cross diffusion coefficients.     

On abelian, triangularizable, total reduction algebras

Suppose that is a complex Hilbert space and that () denotes the bounded linear operators on .In this paper we show that if () is an abelian algebrawith elements that admit representations under which they havea spanning set of eigenvectors, and if has the property that given any bounded representation: () of ona Hilbert space , every invariant subspace of () is topologically complemented by an invariantsubspace of (), then is similar to an abelian C^*-algebra. From thisit follows that any amenable Banach algebra of triangular operatorson a separable Hilbert space is similar to an abelian C^*-algebra.     

An approximate,multivariable version of Specht's theorem

In this article we provide generalizations of Specht's theorem which states that two n × n matrices A and B are unitarily equivalent if and only if all traces of words in two non-commuting variables applied to the pairs (A, A?) and (B, B?) coincide. First, we obtain conditions which allow us to extend this to simultaneous similarity or unitary equivalence of families of operators, and secondly, we show that it suffices to consider a more restricted family of functions when comparing traces. Our results do not require the traces of words in (A, A?) and (B, B?) to coincide, but only to be close.     

Discrete salt crystallization at the surface of a porous medium

Efflorescence refers to crystallized salt structures that form at the surface of a porous medium. The challenge is to understand why these structures do not form everywhere at the surface of the porous medium but at some specific locations and why there exists an exclusion distance around an efflorescence where no new efflorescence forms. These are explained from a visualization experiment, pore-network simulations and a simple efflorescence growth model.     

On the closed Lie ideals of certainC *-algebras

In this article we determine the closed Lie ideals of a uniformly hyperfiniteC ^*-algebra, and of the tensor product of such an algebra withC(X), the space of continuous functions on a compact, Hausdorff space. This is done by localizing the Lie ideals in algebras of the form , where is an algebra over a field of characteristic not equal to 2.This research is partially supported by NSERC (Canada)     

Preparation and novel reduction reactions of vinamidinium salts.

Substituted acetic acids and formamides react in the presence of phosphorus oxychloride to yield the vinamidinium hexafluorophosphate salts 5a-d, 6a-d, and 7 in moderate to good unoptimized recrystallized yields (40-67%) as easily handled nonhygroscopic solids. The 1,3-differentially substituted vinamidinium salts 8 was prepared by amine exchange in 81% yield as are the cyclic diazapinium salts 9 and 10 in > 76% yield. The symmetrical 2-chlorovinamidinium 11 was prepared by displacement of 3 in 71% yield. The 2-chlorovinamidinium salts are cleanly reduced to the parent vinamidinium salts 12-16 using HI or PPh3/pTSA in up to 99% assay yield.