Multi-catalysis reactions: direct organocatalytic sequential one-pot synthesis of highly functionalized cyclopenta[b]chromen-1-ones

We have developed a new technology called multi-catalysis for the sequential one-pot synthesis of highly functionalized heterocycles. A practical and novel multi-component aniline-, self- and Br?nsted acid-catalyzed selective process for the sequential one-pot synthesis of highly substituted 2-(2-hydroxy-aryl)-cyclopentane-1,3-diones, 3,9-dihydro-2H-cyclopenta[b]chromen-1-ones and 3,3-dimethyl-2,3,4,9-tetrahydro-xanthen-1-ones is reported. Direct combination of aniline- and self-catalyzed cascade olefination-hydrogenation (O-H) and Br?nsted acid-catalyzed cascade oxy-Michael-dehydration (OM-DH) of 1,3-diones, salicylic aldehydes and organic-hydrides is developed in one-pot to furnish the highly functionalized 3,9-dihydro-2H-cyclopenta[b]chromen-1-ones and 3,3-dimethyl-2,3,4,9-tetrahydro-xanthen-1-ones with high yields.     

Facile One‐Pot Multicomponent Synthesis of β‐Acetamido Ketones with Amberlyst‐15 as Heterogeneous Catalyst

The one‐pot multicomponent coupling of an aromatic aldehyde, an enolizable ketone or keto ester, acetonitrile, and acetyl chloride at room temperature in the presence of Amberlyst‐15 as catalyst affords β‐acetamido ketones in high yields. The inexpensive catalyst works under heterogeneous conditions and can be readily reused.     

Double cascade reactions based on the Barbas dienamine platform: highly stereoselective synthesis of functionalized cyclohexanes for cardiovascular agents

The amino acid proline catalyzed the three- and five-component cascade olefination-Diels-Alder-epimerization and olefination-Diels-Alder-epimerization-olefination-hydrogenation reactions of readily available precursors enones 1a-i, arylaldehydes 2a-k, alkyl cyanoacetates 3a-e and Hantzsch ester 9 to furnish highly substituted prochiral 1-cyano-4-oxo-2,6-diaryl-cyclohexanecarboxylic acid alkyl esters 6 and 1-cyano-4-(cyano-alkoxycarbonyl-methyl)-2,6-diaryl-cyclohexanecarboxylic acid alkyl esters 10 in a highly diastereoselective fashion with excellent yields. Prochiral cis-isomers 6 are excellent starting materials for the synthesis of cardiovascular agents and hypnotic active products.     

pi-Conjugated macrocycles from thiophenes and benzenes

pi-Conjugated macrocycles consisting of thiophenes and benzenes exhibit benzenoid features for 4npi macrocycles, whereas (4n + 2)pi macrocycles are annulenoid due to rapid interconversion between quinoid and Kekule canonical forms in the benzene units.     

Total synthesis and stereochemical confirmation of manassantin A, B, and B1

Stereocontrolled total syntheses of manassantins A, B, and B1 and saucerneol are described for the first time based on a novel cycloetherification of end-differentiated benzylic alcohols as a common intermediate. [structure: see text].     

Cu(OTf)2/Cu-catalyzed four-component reaction: a facile synthesis of α-alkoxytriazoles via click chemistry

Aldehyde, alcohol, azide, and alkyne undergo smooth coupling by means of acetal formation, azidation, and a subsequent ‘click reaction’ in the presence of copper(II) triflate and copper metal in acetonitrile to furnish α-alkoxy-1,2,3-triazoles in good yields. The method provides a convenient route to prepare a wide range of triazoles in a one-pot operation via a four-component reaction.     

Ligand dependence of the synthetic approach and chiroptical properties of a magic cluster protected with a bicyclic chiral thiolate

Chiral gold clusters stabilised by enantiopure thiolates were prepared, size-selected and characterised by circular dichroism and mass spectrometry. The product distribution is found to be ligand dependent. Au(25) clusters protected with camphorthiol show clear resemblance of their chiroptical properties with their glutathionate analogue.     

Simple and one-pot protocol for synthesis of indene-spiro-oxindoles involving tandem Prins and Friedel-Crafts reactions

[reaction: see text] A simple and one-pot protocol for the synthesis of indene-spiro-oxindole derivatives via TiCl4-mediated reaction between 1,1-diarylethylenes and isatin derivatives involving construction of two carbon-carbon bonds through tandem Prins and intramolecular Friedel-Crafts (PFC) reactions has been described. A plausible mechanism for this transformation is also presented.     

Synthesis of functionalized carboranes as potential anticancer and BNCT agents

Carboranyl aldehydes react with alpha,beta-unsaturated esters, ketones, and nitriles in the presence of DABCO to provide functionalized carboranyl alcohols in good yields. Acetates of these alcohols undergo a facile isomerization with a variety of nucleophiles and afford structurally interesting carboranes. Biological evaluation of these molecules exhibited impressive antiproliferative activity for brain and breast cancer cells.     

Human cytokines characterized by dielectric thermal analysis, thermogravimetry, and differential scanning calorimetry

Malaria affects over 500 million people worldwide leading to 1–2 million deaths each year, the majority of whom are children. Four Plasmodium species cause malaria in humans. To properly diagnose, and correctly treat malarial infections, accurate diagnosis of infection is required. Proper diagnosis of infection will result in a reduction of morbidity, mortality, and of drug resistant parasites. However, the current tests for malaria diagnosis do not efficiently identify the appropriate human and parasite biomarkers associated with disease. Detection of specific inflammatory mediators such as cytokines associated with malaria pathogenesis will aid the determination of disease progression, disease prognosis, and the early diagnosis of malaria infection. In this study, we used dielectric thermal analysis (DETA), thermogravimetric analysis, and differential scanning calorimetry (DSC) to characterize five human cytokines (IL-1α, IL-2, IL-4, IL-6, and IL-10), to demonstrate how their thermoanalytical properties can be investigated for sensor design. Analysis for DETA was performed at a frequency range of 0.1–300,000 Hz. Permittivity and loss factor measurements were used to calculate tan δ values. Peak frequencies were used to determine dielectric signatures for each cytokine. The peak frequencies were different for each cytokine analyzed. In addition, activation energies were frequency dependent for IL-2 but frequency independent for the remaining four cytokines. Cytokines were also examined using DSC which established variance in heat of crystallization and heat of fusion of solvent among the five cytokines. A noticeable differentiation was observed with IL-1α among the other four cytokines when analyzed using trend analysis. Detection of unique dielectric signals will aid development of sensitive dielectric sensors capable of detecting cytokines in various human samples.