Studies on the constituents of bocconia cordata. IV. Transformation of sanguinarine into bocconine

Nitration of ethoxysanguinarine with equimolar potassium nitrate and sulfuric acid, followed by treatment with sodium hydroxide and methanol, gives 10-nitromethoxysanguinarine. Successive hydrogenation, diazotization and methanolysis convert 10-nitromethoxysanguinarine into bocconine.     

A novel approach to the synthesis of bicyclic lactones via an interrupted Nazarov reaction of gem-divinyl dihydrofurans

[reaction: see text] A facile Lewis acid induced interrupted Nazarov reaction of gem-divinyl dihydrofurans to bicyclic lactones is described.     

Two unprecedented multicomponent reactions involving N-heterocyclic carbenes, activated acetylenes, and aldehydes

[reaction: see text] Two unprecedented multicomponent reactions of N-heterocyclic carbenes involving activated acetylenes and aldehydes are described.     

E‐1,2‐diarylsulfonylethene—Source for new class of heterocycles

A new class of pyrazolidinediones, isoxazolidinediones, pyrimidinetriones, and thioxopyrimidinediones were synthesized by the reaction of Michael adduct, dimethyl 2‐(1′,2′‐diarylsulfonyl)ethylmalonate with different nucleophiles, hydrazine hydrate, hydroxylamine hydrochloride, and urea derivatives. J. Heterocyclic Chem., 2011.     

Quantifying chaotic synchronization using error evolution

Evolution of synchronization error is used to quantify synchronization between coupled chaotic oscillators. A conceptually and computationally simple method to quantify synchronization is proposed by defining synchronization error decay coefficient (SEDC). SEDC can act as a bounded index of quality of synchronization, and indicator of nature of stability of synchronization. This measure is found efficient in detecting even the slightest change in the level of synchronization effected by the presence of noise in the drive signal.     

Three multicomponent reactions of 3,5-dimethyl-4-nitroisoxazole

The title compound is used to prepare 3-arylglutaric acids, bis-isoxazoles and bis-pyrazoles from commercially available materials. The methodologies described have afforded important synthetic intermediates in high yields and without the use of chromatography.     

Synthesis,Evaluation and Proposed Binding Pose of Substituted Spiro-Oxindole Dihydroquinazolinones as IRAP Inhibitors

Insulin-regulated aminopeptidase (IRAP) is a new potential macromolecular target for drugs aimed for treatment of cognitive disorders. Inhibition of IRAP by angiotensin IV (Ang IV) improves the memory and learning in rats. The majority of the known IRAP inhibitors are peptidic in character and suffer from poor pharmacokinetic properties. Herein, we present a series of small non-peptide IRAP inhibitors derived from a spiro-oxindole dihydroquinazolinone screening hit (pIC₅₀ 5.8). The compounds were synthesized either by a simple microwave (MW)-promoted three-component reaction, or by a two-step one-pot procedure. For decoration of the oxindole ring system, rapid MW-assisted Suzuki-Miyaura cross-couplings (1 min) were performed. A small improvement of potency (pIC₅₀ 6.6 for the most potent compound) and an increased solubility could be achieved. As deduced from computational modelling and MD simulations it is proposed that the S-configuration of the spiro-oxindole dihydroquinazolinones accounts for the inhibition of IRAP.     

Unprecedented reactivity of N-heterocyclic carbenes toward DMAD and aldehydes leading to novel multicomponent reactions

A facile synthesis of highly functionalized 2-oxymaleate and furanone derivatives by the multicomponent reaction of 1,3-dimesityl imidazolin-2-ylidene/imidazol-2-ylidene, DMAD, and aldehydes is described.