Naphtho[1′,2′:5,6]pyrano[2,3–6][1,5]benzodiazepine Derivatives

The reaction of 3-(dimethylamino)-1-oxo-1H-naphtho[2,1-b]pyran-2-carbaldehyde (Ia) with o-phenylenediamines or N-monosubstituted o-phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(8H)ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N-monosubstituted o-phenylenediamine hydrochlorides. The isolation of a significant intermediate as well as the synthesis through a different univocal pathway confirmed the structure of the compounds V. Moreover the reaction of Ia with N-monosubstituted o-phenylenediamines in refluxing pyridine generally afforded only low yields of compounds V, sometimes together with naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(13H)ones VII, isomers of V.     

1,2-fused pyrimidines. V. Synthesis of 1-alkyl or phenyl-2H-dipyrido-[1,2-a:2′,3′-d]pyrimidine-2,5(1H)-diones

The reaction of 2-[(N-acyl, N-alkyl or phenyl)amino]-4H-pyrido[1,2-a]pyrimidin-4-ones 8a-g with the N,N-dimethylformamide/phosphorus oxychloride Vilsmeier reagent 1 (95°, 90 minutes) afforded 1-alkyl or phenyl-2H-dipyrido[1,2-a:2′,3′-d]pyrimidine-2,5(1H)^?diones, 3-alkyl substituted or not, 10a-g . The starting compounds 8 were prepared by treating 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones N-alkyl substituted 7a,b or N-phenyl substituted 4 with excess anhydrides (130°, 7 hours) when the 2-(alkylamino) derivatives 7 were used in the reaction, compounds 8 were obtained along with very small amounts of 3-acyl-2-(alkylamino)-4H-pyrido[1,2-a]pyrimidin-4-ones 9 .     

Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2

Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding material properties. These properties mainly rely on maximizing the number of strong covalent bonds, with crosslinked XN₆ octahedra frameworks being particularly attractive. In this study, the phosphorus–nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells, and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. δ-P₃N₅ and PN₂ were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN₆ units. The two compounds are ultra-incompressible, having a bulk modulus of K₀=322 GPa for δ-P₃N₅ and 339 GPa for PN₂. Upon decompression below 7 GPa, δ-P₃N₅ undergoes a transformation into a novel α′-P₃N₅ solid, stable at ambient conditions, that has a unique structure type based on PN₄ tetrahedra. The formation of α′-P₃N₅ underlines that a phase space otherwise inaccessible can be explored through materials formed under high pressure.     

Novel stereocontrolled addition of allylmetal reagents to alpha-imino esters: efficient synthesis of chiral tetrahydroquinoline derivatives

To prepare in multigram scale new antagonists of the glycine binding site associated to the NMDA receptor, an efficient distereoselective route was set up. The addition of suitable allyltin reagents to chiral N-aryl alpha-imino esters (R-(+)-tert-butyl lactate used as chiral auxiliary), gave the corresponding alpha amino acid-type derivative in high chemical yield and optical purity. This allylation reaction represents a novel example of efficient long-range stereodifferentiation process. In the last part of the synthesis, a regioselective Heck-type cyclization reaction enabled preparation of the target tetrasubstituted exocycle and trisubtituted endocycle double bond derivatives.     

Stability in the Rotating Bénard Problem and Its Optimal Lyapunov Functions

Stability analysis of the rotating Bénard problem gives a spectral instability threshold of the purely conducting solution that can be expressed as a critical Rayleigh number R ² depending on the Taylor number T ². The definition of a functional which can be used to prove Lyapunov stability up to the threshold of spectral instability (optimal Lyapunov function) is an important step forward both, for a proof of nonlinear stability and for the investigation of the basin of attraction of the equilibrium. In previous works a Lyapunov function was found, but its optimality could be proven only for small T ². In this work we describe the reason why this happens, and provide a weaker definition of Lyapunov function which allows to prove that, for the linearized system, the spectral instability threshold is also the Lyapunov stability threshold for every value of T ².     

The ultraviolet spectra of the chloropyridines and chlorinated pyridines possessing a sulfur (-SR), nitrogen (-NR2), or oxygen (-OR) substituent in either the 2 or 4-position: A convenient method for distinguishing such positional isomers

The ultraviolet spectra for a series of 15 chlorinated pyridines which contain a sulfur, nitrogen or an oxygen substituent at either the 2 or 4-position have been examined. A correlation has been established between the position (2 vs 4) of the S, N, or O substituent on the chlorinated pyridines and their ultraviolet spectra. It was found that the chlorinated pyridines with S, N, or O substitution at the 2-position gave ultraviolet spectra whose longest wavelength absorption maxima were enhanced (moved to a greater wavelength and an increased extinction coefficient) when compared to the spectra of the 4-substituted isomers. The difference is great enough so that an easy identification of positional isomers can be made with a relatively high degree of confidence even when only one positional isomer is available. The ultraviolet spectra of all the chlorinated pyridines has been recorded, and it was observed that the number of chlorine atoms, and not their position, was the more significant factor in determining the overall character of the spectra.     

Novel developments for the production of 6APA in the penicillin g fermentation plant by using fiber-entrapped penicillin amidase

The production of 6APA by enzymatic hydrolysis of penicillin G can be integrated with the production of penicillin G. The penicillin G solutions obtained during the extraction from the fermented broth can be directly hydrolyzed to 6APA and phenyl acetic acid. The 6APA is then recovered while the phenyl acetic acid can also be recovered and recycled to the fermentation plant. Some of the results obtained by the research work performed by SNAM Progetti in their Microbiological Laboratories with the advice of Biochem Design are presented and analyzed. The economic potential of the integrated process is discussed.     

A mathematical model of anorexia and bulimia

In this paper, we propose a mathematical model to study the dynamics of anorexic and bulimic populations. The model proposed takes into account, among other things, the effects of peers' influence, media influence, and education. We prove the existence of three possible equilibria that without media influences are disease‐free, bulimic‐endemic, and endemic. Neglecting media and education effects, we investigate the stability of such equilibria, and we prove that under the influence of media, only one of such equilibria persists and becomes a global attractor. Which of the three equilibria becomes global attractor depends on the other parameters. Copyright © 2014 John Wiley & Sons, Ltd.