Designing and Synthesis of Novel Amidated Fentanyl Analogs

Some new amidated fentanyl (=N‐[1‐(2‐phenylethyl)piperidin‐4‐yl]‐N‐phenylpropanamide) analogs with a 4‐(N‐phenylamido)piperidine scaffold and additional amide bonds have been designed and synthesized through Ugi four‐component reaction (Ugi‐4CR). Good‐to‐high yields, diversity‐oriented synthesis, and possible applications in drug discovery are advantages of this approach.     

Rotating waves within a hollow vortex core

The rotating waves within a hollow vortex core (polygonal patterns) are generated under shallow water conditions inside a cylindrical tank by a revolving disk at its bottom. We previously reported some basic features of these polygonal patterns during transition and at the equilibrium states. The present paper includes a more comprehensive investigation into the transition process of these polygonal patterns and expands the recent partial results that have been previously reported. We show that the parent wave (or the N-gon pattern) to disk frequencies ratio is around one-third (1/3) regardless of the flow conditions. A detailed insight into the transition process from the parent wave N-gon to daughter wave (N + 1)-gon is provided, which consists of two regimes, quasi-periodic and synchronized. Based on these observations, we explained the shrinking of the disk speed subintervals over which the N-gon patterns occur, when N increases.     

Crystal Structure of the Second Polymorph of Octaethylporphyrin Iron(III) with Monoanion 1,4-Phenyldicyanamide, [Fe(OEP)(DicydH)]

Abstract  

Molecular structure of the second polymorph of [Fe(OEP)(DicydH)], where OEP is the dianion of octaethylporphyrin and DicydH = monoanion of 1,4-phenyldicyanamide, was determined by single-crystal X-ray diffraction. Fe(III) atom is five-coordinate to four N atoms of the porphyrin ring and to one nitrogen atom of DicydH. The compound is characterized by an average Fe–N_p bond length of 2.057 ?. The Fe–N_ax bond distance is 1.969(6) ?. Crystal data: crystal system, orthorhombic, a = 15.048(2), b = 17.515(3), c = 29.440(4) ?, space group, Pcab, V = 7759(2) ?³, Z = 8.     

Classification of Curves in 2D and 3D via Affine Integral Signatures

We propose new robust classification algorithms for planar and spatial curves subjected to affine transformations. Our motivation comes from the problems in computer image recognition. To each planar or spatial curve, we assign a planar signature curve. Curves, equivalent under an affine transformation, have the same signature. The signatures are based on integral invariants, which are significantly less sensitive to small perturbations of curves and noise than classically known differential invariants. Affine invariants are derived in terms of Euclidean invariants. We present two types of signatures: the global and the local signature. Both signatures are independent of curve parameterization. The global signature depends on a choice of the initial point and, therefore, cannot be used for local comparison. The local signature, albeit being slightly more sensitive to noise, is independent of the choice of the initial point and can be used to solve local equivalence problem. An experiment that illustrates robustness of the proposed signatures is presented.     

Erratum to: The catalytic effect of Al-KIT-5 and KIT-5-SO3H on the conversion of fructose to 5-hydroxymethylfurfural

Research on Chemical Intermediates -     

Novel isocyanide-based three-component reaction: a facile synthesis of substituted 1H-chromeno[2,3-d]pyrimidine-5-carboxamides

A mild and efficient method for the synthesis of 1H-chromeno[2,3-d]pyrimidine-5-carboxamide derivatives via a one-pot, three-component reaction of an isocyanide, barbituric acid, and a salicylaldehyde in the presence of acetic acid in ethanol/water mixture at 75 °C is reported. This high atom economy reaction led to the construction of one benzopyran ring, and one amide group in a single synthetic step.     

Effects of length and number of aromatic rings in carboxylic acid ligands on structure and optical properties of lead(II) coordination polymers

Research on Chemical Intermediates - To systematically examine the effects of the length and number of aromatic rings in carboxylic acid ligands on the structure and properties of lead(II)...     

Palladium-catalyzed stereoselective synthesis of 3-(aminomethylene)-oxindoles

An efficient palladium-catalyzed protocol for the stereoselective synthesis of 3-(aminoarylmethylene)-oxindoles has been developed. In this approach, Ugi-4-component reaction adducts were used as starting materials for carbopalladative cyclization-Buchwald reaction sequences.     

Photo-oxidation of 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones

A variety of Biginelli 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones are efficiently oxidized to their corresponding pyrimidin-2(1H)-one derivatives upon UV irradiation under argon atmosphere in chloroform solution. The nature of the additional substituent on the phenyl ring located on C-4 of the heterocyclic ring influences the rate of reaction. An electron-transfer induced photoreaction is proposed based on the formation of HCl and CH₂Cl₂.