An efficient synthesis of β-acylureas via a three-component, one-pot synthesis using TCS/ZnCl2

A simple and efficient one-pot, three-component synthesis of new trisubstituted ureas containing diastereotopic protons is achieved via the reaction of aromatic aldehydes, aromatic ketones, and dimethyl cyanamide using a TCS/ZnCl₂ reagent mixture at room temperature.     

SYNTHESIS AND MOLECULAR STRUCTURE OF [Cu(μ-OC6H3-2,6-Me2)(thd)]2: A LIGAND-MEDIATED REDUCTION TO METALLIC COPPER

Abstract

The reaction between barium 2,6-dimethylphenoxide (1) and copper 2,2,6,6-tetramethylheptane-3,5-dionate gave the volatile β-diketonatoaryloxide [Cu(μ-OC₆H₃-2,6-Me₂)(thd)]₂ (2). The complex was characterized by elemental analysis, IR and ESR spectroscopy as well as single-crystal X-ray diffraction. It crystallises in the space group P2₁ /c with a = 6.602(2), b = 24.454(5), c = 12.391(4) Å, β = 95.49(2)°. TGA experiments at 1 atmosphere show that 2 is volatile and decomposes at 292°C to metallic copper by a ligand-mediated reduction.     

The effect of 2-hydroxypropyl-β-cyclodextrin on the excited triplet state of promazine and chlorpromazine

Chlorpromazine hydrochloride (CPZ) is a widely used anti-psychotic drug that induces skin photosensitization and photoallergy response after systematic use or topical applications. The photoallergic mechanism is still unknown. However, it has been proposed that the triplet excited state (³CPZ*) could participate in the photodamaging effects. In this work, we report the photophysical properties of the triplet excited state of CPZ and its parent derivative promazine hydrochloride (PZ) in the presence of 2-hydroxypropyl-β-cyclodextrin (HPC). Absorption measurements indicate that PZ and CPZ form an inclusion complex with HPC through a 1:1 stoichiometry. The equilibrium constant at 25 °C is (2.55 ± 0.09) × 10³ M⁻¹ and (3.27 ± 0.07) × 10³ M⁻¹ for PZ and CPZ, respectively. The CPZ and PZ triplet excited state properties changed in the presence of HPC. The triplet lifetime increases with HPC concentration that is related to the amount of drug bound. In addition, the triplet intersystem crossing quantum yield was determined to be 0.45 and 0.17 for PZ and CPZ, respectively, when more than 95% of the drug molecules are bound to HPC. Altogether, these results suggest that the microenvironment plays a crucial role in the ³CPZ* and ³PZ* properties and thus it can modulate their photosensitizing effects.     

Synthesis and Crystal Structure Analysis of 9-Phenyl-β-carboline

An efficient method is described for the synthesis of 9-phenyl-9H-pyrido[3,4-b]indole and 9-(4-chlorophenyl)-9H-pyrido[3,4-b]indole by employing a catalytic amount of CuI (10 mole%) without any ligand. The single crystal of 9-phenyl-9H-pyrido[3,4-b]indole was produced by crystallization from hexane and ethyl acetate mixture that was investigated by single X-ray diffraction (XRD). The compound crystallizes in monoclinic P21/c space group with unit cell dimensions a = 11.3132(5) Å, b = 12.0061(5) Å, c = 9.2498(4) Å, α = 90°, β = 103.187(3)°, γ = 90°. ¹H and ¹³C NMR, IR, and mass spectroscopic methods of the compounds are also discussed.     

概率度量空间中广义β-可容许映射的二元重合点定理及其应用

在Menger PM-空间中,引入广义β-可容许映射的概念。在不要求两映射可交换的情况下,利用迭代法,建立了广义β-可容许映射的二元重合点定理。获得了一些新的结果,推广和改进了相关文献中的不动点定理和二元重合点定理。最后,给出了主要结果的一个应用。     

Computing tolerance limits for the lifetime of a k-out-of-n:F system based on prior information and censored data

Exact guaranteed-coverage and expected-coverage Bayesian tolerance limits for the lifetime distribution of a k-out-of-n:F system are computed by solving nonlinear equations. The bounds are based on exponential component test data and available prior information concerning the expected component lifetime which is described by an inverted gamma distribution. The Bayesian tolerance limits are valid for single (right or left), double and progressive (standard or general) censoring, and even have frequentist validity in the noninformative case. The derived results allow the reliability engineer to judge the quality of a system prior to assembly, which offers obvious practical and economic benefits. Minimum and expected percentages of conforming systems are assessed by constructing suitable tolerance limits. Even though the viewpoints are different, the Bayesian tolerance limits that adopt the natural diffuse prior coincide numerically with recently published conditional tolerance limits in the double censoring case. The proposed Bayesian approach may be deemed as an extension of the existing frequentist methodology under double censoring that also takes into account the presence of prior information and general progressive censoring. The perspective developed simplifies and unifies the computation of tolerance limits with both frequentist and Bayesian interpretations, and also provides a probabilistic way of updating the tolerance limits in the light of new, relevant data, which is especially important in the dynamic analysis of a sequence of data. Moreover, the Bayesian approach is shown to outperform the frequentist viewpoint in terms of accuracy. In most situations, the use of substantial prior information significantly increases the accuracy level and considerably reduces the required number of failures to attain a specified degree of accuracy. Two illustrative numerical examples are studied, including the analysis of a system of water pumps for cooling a reactor. The results developed are extended to the Weibull case with unknown scale parameter and other probability models.     

Effects of Homogenization Models and Emulsifiers on the Physicochemical Properties of β-Carotene Nanoemulsions

Microfluidization and high pressure valve homogenization were applied to prepare β-carotene nanoemulsions, and the mathematical relationship between homogenization pressures and emulsion temperatures, homogenization pressures/cycles, and droplet sizes, were established. Emulsions through Microfluidizer had lower temperature and much smaller droplet sizes, compared with those through high pressure valve homogenizer. Four emulsifiers were compared for their capacities to stabilize nanoemulsions. The two large molecule emulsifiers, octenyl succinate starch (OSA) and whey protein isolate (WPI), were less effective for the formation of nanoemulsions with smaller droplets than the two small molecule emulsifiers, polyoxyethylene sorbitan monolaurate (Tween 20, TW) and decaglycerol monolaurate (DML). The nanoemulsion containing WPI was the most stable, while the one containing DML was the least stable. During storage, significant degradation of β-carotene occurred in all nanoemulsions, especially in the DML stabilized one, while WPI showed the greatest capacity to protect β-carotene from degradation.     

Synthesis of Chiral Benzofuran-Derived β-Amino Esters Induced by N-tert-Butanesulfinamide

The benzofuran skeleton is commonly found in a wide variety of natural products that display a wide range of biological activities. For this reason, benzofuran has a high potential for use as a scaffold in both chemical and pharmaceutical syntheses of natural products. This work describes the development of a novel asymmetric synthetic method of benzofuran-derived β-amino esters via K₂CO₃-promoted domino reactions of ortho-hydroxyl aromatic N-tert-butylsulfinyl imines and diethyl bromomalonate. A small library of target compounds was prepared under optimized reaction conditions in moderate to good yields with high distereoselective and enantioselective properties. The newly generated chiral carbon center was of an (S)-configuration as determined by x-ray diffraction.     

Stereoselective Synthesis of β-Amino Ketones: A Three-Component Mannich-Type Reaction of Aromatic Aldehydes,Anilines, and Cyclohexanone Using Amberlyst-15

A three-component Mannich-type reaction of aromatic aldehydes, anilines, and cyclohexanone in the presence of Amberlyst-15 affords the corresponding β-amino ketones in good yields at room temperature. The conversion is highly diastereoselective, favoring the formation of anti-isomers.