Total synthesis of Cinncassin A1

In this communication, we report the first total synthesis of the phenolic natural product Cinncassin A₁, which was recently isolated from the twigs of the cinnamon plant (Cinnamomum cassia). The novel and concise synthesis strategy involves a highly diastereoselective titanium enolate homocoupling and a permanganate-mediated oxidative lactonization reaction as key steps. The structure of the compound was verified by single-crystal X-ray crystallography.     

Crystallization kinetics and morphology of poly(lactic acid) with polysaccharide as nucleating agent

Journal of Thermal Analysis and Calorimetry - An ever-increasing concern about environmental pollution has spearheaded research into alternative biodegradable polymers. Currently, poly(lactic acid)...     

Efficacy of nanolime in restoration procedures of salt weathered limestone rock

Salt crystallisation process is one of the most powerful weathering agents in stone materials, especially in the coastal areas, where sea-spray transports large amount of salts on the stone surface. The consolidation of such degraded stone material represents a critical issue in the field of restoration of cultural heritage. In this paper, the nanolime consolidation behaviour in limestone degraded by salt crystallization has been assessed. For this purpose, a stone material taken from a Sicilian historical quarry and widely used in the eastern Sicilian Baroque architecture has been artificially degraded by the salt crystallization test. Then degraded samples have been treated with NanoRestore^®, a suspension of nanolime in isopropyl alcohol. To evaluate the consolidating effectiveness, the peeling test and point load test were performed. Moreover, mercury intrusion porosimetry has been executed to evaluate the variations induced by treatment, while colorimetric measurements have been aimed to assess aesthetical issues.     

Zero–Hopf bifurcation in a hyperchaotic Lorenz system

We characterize the zero–Hopf bifurcation at the singular points of a parameter codimension four hyperchaotic Lorenz system. Using averaging theory, we find sufficient conditions so that at the bifurcation points two periodic solutions emerge and describe the stability of these orbits.     

Cycloadditions of methyl dichloroacetate to electrophilic alkenes

Seven MIRC reactions of methyl dichloroacetate with alkenes containing electron-withdrawing groups were used to make 1-chlorocyclopropanecarboxylates.     

Kinetic study of the formation of N‐chloro compounds using N‐chlorosuccinimide

Second‐order rate constants were determined for the chlorination reaction of 2,2,2‐trifluoethylamine and benzylamine with N‐chlorosuccinimide at 25 °C and an ionic strength of 0.5 M. These reactions were found to be of first order in both reagents. According to the experimental results, a mechanism reaction was proposed in which a chlorine atom is transferred between both nitrogenous compounds. Kinetics studies demonstrate that the hydrolysis process of the chlorinating agent does not interfere in the chlorination process, under the experimental conditions used in the present work. Free‐energy relationships were established using the results obtained in the present work and others available in the literature for chlorination reactions with N‐chlorosuccinimide, being the pK_a range included between 5.7 and 11.22. Copyright © 2014 John Wiley & Sons, Ltd.     

Real Valuations on Skew Polynomial Rings

Let D be a division ring, T be a variable over D, σ be an endomorphism of D, δ be a σ-derivation on D and R?=?D[T; σ, δ] the left skew polynomial ring over D. We show that the set \((Val_\nu(R),\preceq)\) of σ-compatible real valuations which extend to R a fixed proper real valuation ν on D has a natural structure of parameterized complete non-metric tree, where \(\preceq \) is the partial order given by \(\mu \preceq \widetilde{\mu}\) if and only if \(\mu (f)\leq \widetilde{\mu}(f)\) for all f?∈?R and \(\mu, \widetilde{\mu} \in Val_\nu (R)\) . Furthermore and as a consequence, we also prove a criterion of irreducibility for left skew polynomials that includes as a particular case an Eisenstein valuation criterion which generalizes a similar one of Churchill and Zhang (J Algebra 322:3797–3822, 2009).