Etude cinetique de la catalyse par LiClO4 de la reaction d'esterification des olefines

LiClO₄ catalyses the addition of CHCl₂CO₂H to olefins (cyclopentene cycloheptene and trans-cyclo-octene). Specific salt effects are discussed in terms of general acid catalysis. This mechanism is supported by the linear relation: log k_ex = ? αH_o + β. Solvent isotope effects show a slow proton transfer. Eyring parameters are determined; ΔS* < 0. These experiments are consistent with a mechanism involving carbocation formation as the slow step.     

On uniform propagation of chaos

In this paper we obtain a time-uniform propagation estimate for a system of interacting diffusion processes. Using a well defined metric function h , our result guarantees a time-uniform estimate for the convergence of a class of interacting stochastic differential equations towards their mean field limit, under conditions that ensure that the decay associated to the internal dynamics term dominates the interaction and noise terms. Our result should have diverse applications, particularly in neuroscience, and allows for models more elaborate than the one of Wilson and Cowan. In particular, the internal dynamics need not be that of linear decay.     

A practical route to enantiopure 3-hydroxy-pyrrolidines: application to a straightforward synthesis of (−)-bulgecinine

A practical synthesis of enantiopure substituted 3-hydroxy-pyrrolidines is reported. In four steps, starting from commercially available amino acids as chiral educts, this method allows for an efficient preparation of a variety of 3-hydroxy-pyrrolidines, as well as 3-hydroxy-piperidines and azepanes. Application of this methodology for a straightforward asymmetric synthesis of (−)-bulgecinine is also described.     

Concise, flexible syntheses of 4-(4-imidazolyl)pyrimidine cyclin-dependent kinase 2 (CDK2) inhibitors

A flexible six-step synthesis of potential cyclin-dependent kinase 2 (CDK2) inhibitors is reported. The synthesis involves the condensation between 3-chloro-4,4-dimethoxy-2-butanone and amidines, which provides acetyl-imidazoles and late stage palladium-catalyzed N-arylation to give the target pyrimidine derivatives.     

A simple proof for a theorem of Luxemburg and Zaanen

In this paper a simple proof for the following theorem, due to Luxemburg and Zaanen is given: an Archimedean vector lattice A is Dedekind σ-complete if and only if A has the principal projection property and A is uniformly complete. As an application, we give a new and short proof for the following version of Freudenthal's spectral theorem: let A be a uniformly complete vector lattice with the principal projection property and let 0<u∈A. For any element w in A such that 0?w?u there exists a sequence in A which satisfies , where each element sn is of the form , with real numbers α₁,…,αk such that 0?αi?1 (i=1,…,k) and mutually disjoint components p₁,…,pk of u.     

Total synthesis of chaetominine

An efficient, asymmetric synthesis of the cytotoxic natural product chaetominine was achieved in 14 steps. The strategy employs a copper(I)-mediated cyclization reaction as a key step to install the abc-tricyclic ring system, which was further elaborated by diastereoselective oxidation and reduction reactions. This effort also documents the first example of an oxidative rearrangement yielding to homochiral spirocyclic pyrrolidinyloxindoles.     

A relationship between the space of orthomorphisms and the centre of a vector lattice revisited

In (Chil et al. Positivity, 2014), the authors claim to give a counterexample to the main result, about Wickstead’s question, in a recent paper of Toumi (see Theorem 3, When orthomorphisms are in the ideal center, Positivity 18(3):579–583, 2014). In this note we show that their example is consistent with the main result of Toumi and not a counterexample.     

Raman spectroscopic study of K3H(SO4)2 (phases I and II) single crystals

A Raman study of K₃H(SO₄)₂ as a function of temperature reveals that this compound undergoes a phase transition at T_c = 483 K prior to the decomposition at 508 K.     

Investigations of the reduced Redlich–Kister excess properties of 1,4-dioxane + isobutyric acid binary mixtures at temperatures from 295.15 to 313.15 K

Excess molar volumes and refractive index, molar refraction deviations and isentropic compressibility changes in 1,4-dioxane + isobutyric acid binary mixtures (from 295.15 to 313.15) K. were calculated from experimental density, refractive index and sound velocity data presented in previous work. Here, these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation as well as their corresponding relative functions which are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. The results of these observations have been interpreted in terms of structural effects of the solvents. The correlating equation recently proposed by Belda, has also been applied to the present system in order to assess the validity of this equation and to give thermodynamic limiting partial molar quantities interesting to evaluate solute–solvent interaction.