KI‐VO(acac)2‐H2O2‐AcOH,A New Iodinating System for Selective Iodination at C‐5 Position of Activated Pyrimidinediones: A Combined Experimental and Density Functional Study

KI‐VO(acac)₂‐H₂O₂ in aqueous ethanolic medium with acetic acid as additive has been found to iodinate pyrimidinediones and aromatic amines. The methodology is mild, efficient, and environmentally benign. Density functional theory‐based reactivity parameters support the experimentally observed reactivity of pyrimidinedione derivatives.     

Some new modular equations in Ramanujan’s alternate theory of signature 3

The Ramanujan Journal - In this paper, we prove some new modular equations in the theory of signature 3 or cubic modular equations by using theta-function identities. Particularly, we prove modular...     

An improved stereoselective total synthesis of (R)-rugulactone

A novel route for the stereoselective total synthesis of (R)-rugulactone 1 has been developed, starting from substituted epoxide 4 and 3-phenylpropionaldehyde 5 employing Julia-Kocienski olefination as a key step to construct E-configured α,β-unsaturated keto-group. The overall yield of the synthesized rugulactone is 19.94% and is better than the reported methods.     

Synthesis of oxabicyclo[3.3.1]nonenes and substituted tetrahydropyrans via (3,5)-oxonium-ene reaction

An efficient methodology for the synthesis of oxabicyclo[3.3.1]nonenes and substituted tetrahydropyrans has been developed in moderate yields from the reaction of geraniol with aldehydes and epoxides promoted by boron trifluoride etherate.     

Studies on –SO3H functionalized Brønsted acidic imidazolium ionic liquids (ILs) for one-pot,two-step synthesis of 2-styrylquinolines

Four task-specific –SO₃H functionalized imidazolium ionic liquids (ILs) were investigated for Brønsted acidities by Hammett functions. After knowing their thermal stabilities, the catalytic activity was observed for the preparation of 2-styrylquinolines by following consecutive Friedländer and Knoevenagel reactions in solvent-free thermal energy. The acidity order ([Dsim][OOCCF₃] > [Dsim][OTs] > [Dsim][OOCCl₃] > [Msim][OOCCF₃]) of three ILs was consistent with their activity order observed in the acid-catalyzed synthesis of 2-styrylquinolines under solvent-free conditions at 90° C, with the exception of [Dsim][OTs]. The best catalytic activity was shown by 25 mol% of [Dsim][OOCCF₃] IL. The less acidic IL required 50 mol% to give good yield of 2-styrylquinolines under the optimized condition.     

Identification of Potential Vaccine Candidates Against Streptococcus pneumoniae by Reverse Vaccinology Approach

In the past few decades, genome-based approaches have contributed significantly to vaccine development. Our aim was to identify the most conserved and immunogenic antigens of Streptococcus pneumoniae, which can be potential vaccine candidates in the future. BLASTn was done to identify the most conserved antigens. PSORTb 3.0.2 was run to predict the subcellular localization of the proteins. B cell epitope prediction was done for the immunogenicity testing. Finally, BLASTp was done for verifying the extent of similarity to human proteome to exclude the possibility of autoimmunity. Proteins failing to comply with the set parameters were filtered at each step. Based on the above criteria, out of the initial 22 pneumococcal proteins selected for screening, pavB and pullulanase were the most promising candidate proteins.     

A convenient synthesis of novel 5-aryl-pyrido[2,3-d]pyrimidines and screening of their preliminary antibacterial properties

Exploiting the diene nature of 6-[1-aza-2-(dimethylamino)prop-l-enyl]-1,3-dimethyluracil (2), novel 5-aryl-pyrido[2,3-d]pyrimidines (5a–h) have been synthesized. The reaction proceeds through a triene intermediate whose structure has been conclusively established by single crystal X-ray analysis. Role of water is intriguing as the reaction can be stopped at the intermediate stage. Synthesized compounds have been screened for possible antibacterial properties and results showed modest activity.     

Base-promoted three-component cascade approach to unsymmetrical bis(indolyl)methanes

Here we report a base-catalyzed reaction of two different indoles with aldehydes under heating to produce unsymmetrical bis(indolyl)methanes (BIMs), in which one of the indole ring must be N-substituted. Mixture of EtOH-H₂O is used as solvent. The reaction did not give symmetrical BIMs of N-substituted indoles or N–H indoles. However, traces of latter were formed in few cases, especially when electron-rich aldehydes were used. Diversely substituted indoles and aldehydes were used for the reaction. The reaction proceeds via 3-indolylalcohol, which we confirmed through isolation. The method also gives good yield on multigram scale reaction.     

Acid-base equilibrium of anionic dyes partially bound to micelles of nonionic surfactants

The acid-base equilibria of the sulfonephthalein dyes, namely, bromothymol blue, thymol blue, and cresol red, in aqueous nonionic micellar solutions of Triton X-100, Tween-20, Tween-40, Tween-60, and Tween-80 have been investigated. The equilibrium constants of the partition of the dyes between micellar and aqueous pseudophases have been determined spectrophotometrically at fixed pH. The K(ass) increased with the surfactants in the order Tween-80相似文献   

Design of Supported Organocatalysts from Carboxylic Acids for the Mannich-Type Synthesis of β-Amino Carbonyl Compounds

New supported acidic organocatalysts were prepared by the impregnation of three carboxylic acids (CF₃COOH, CCl₃COOH, and CH₃COOH) on silica support at room temperature in diethyl ether. The catalysts were characterized by scanning electron microscopy, energy dispersion X-ray analysis (EDX), Brunauer-Emmett-Teller-surface-area-analysis (BET), thermogravitational analysis, Fourier transform infrared, and powder X-ray diffractometry analysis. These solid acids were observed as highly efficient reusable catalysts at room temperature for the selective synthesis of β-amino carbonyl compounds via Mannich-type reactions of acetophenone, arylamine and arylaldehydes using two different conditions in CH₂Cl₂ solution and solvent-free grinding within a short time. The more acidic two catalysts could be recycled for up to five cycles with a small loss in catalytic activity.