Silica Supported Perchloric Acid: A Convenient and Environmentally Friendly Catalyst for the One-pot Multicomponent Synthesis of β-Acetamido Ketones

SiO2-supported HClO4 catalyzed synthesis of (Z)-thiazolylhydrazonoindolin-2-ones and their electrochemical properties

In this paper, an environmentally benign silica-supported perchloric acid (HClO₄-SiO₂) catalyzed green FCDR strategy has been developed for the synthesis of (Z)-THIs (6) with high stereospecificity via an intramolecular hydrogen bond (IHB) directed approach, involving the reaction of methyl ketones (1), N-bromosuccinimide (NBS) (2), isatins (4) and thiosemicarbazide (5) in ethanol at reflux temperature for 45-60 min in one-pot. The reaction proceeds through the construction of C-Br (α-bromination), C-S & C-N (heterocyclization), and CN (condensation) bonds in one pot. The absolute structure of the compound (Z)-3-(2-(4-(4-bromophenyl)thiazol-2-yl)hydrazono)indolin-2-one (6e) has been confirmed by single-crystal XRD analysis. Further, the role of IHB on Z-configuration of the synthesized (Z)-THIs is proved by single-crystal XRD and ¹H NMR studies. Wide substrate scope, good functional group tolerance, scalability, improved safety since the method circumvents the use of highly lachrymatric α-bromoketones as starting materials, high product yields (up to 98%), short reaction times, reusable solid Brønsted acid catalyst (HClO₄-SiO₂), and products that do not require column chromatography purification are all attractive features of this FCDR strategy. Electrochemical properties of THIs (6) are examined by cyclic voltammetry. The HOMO and LUMO energy level of THIs, 6a, 6c, 6d, 6j, 6o-6v, 6y, and 6aa are comparable with the reported ambipolar materials, and the HOMO levels of other THIs, 6b, 6e-6i, 6n, 6w, 6x, 6z and 6 ab-6ae are similar with the most commonly used hole transporting materials (HTMs).

One-pot Synthesis of β-acetamido-β-(phenyl) Propiophenone using ZnO/Carbon Nanocomposites

AIM AND OBJECTIVES

The focus of the present work is to synthesize ZnO/C composite using dextrose as carbon source by combustion method and study the comparative evaluation on one-pot synthesis of β-acetamido- β-(phenyl) propiophenone over ZnO nanoparticles and ZnO/C composite catalyst.

MATERIALS AND METHODS

The ZnO nanoparticles has been synthesized by sol-gel method using zinc nitrate and NaOH and ZnO/Carbon composites by combustion method using zinc nitrate and dextrose as carbon source. The resulting gel was placed in a preheated muffle furnace at 400oC. The solution boils and ignites with a flame. On cooling highly amorphous powder of ZnO/Carbon composite is obtained.

RESULTS

The XRD patterns reveal the hexagonal phase with Wurtzite structure and the nanocrystalline nature of the catalysts. The SEM image of ZnO/C composite showed that it contains spherical particles with an average size of 41 nm. The average particle size of the composite was around 60nm by DLS method. The catalytic activity of the ZnO/Carbon composites has been analyzed by one-pot four-component condensation of benzaldehyde, acetophenone, acetyl chloride and acetonitrile. The feed molar ratio of 1:1 (Bz:AP) and catalyst loading of 30 mol% is found to be the optimal condition for β-acetamido ketone conversion over ZnO/carbon composite.

CONCLUSION

The substantial catalytic activity of the synthesized ZnO/C composite materials was tested by one-pot four-component condensation of benzaldehyde (Bz), acetophenone (AP), acetyl chloride (AC) and acetonitrile (AN) which showed a high β-acetamido ketone conversion under the optimized reaction conditions. It has also been found that the catalyst is very stable and reusable.

CeO2 nanoparticles: A robust and reusable heterogeneous catalyst for the diastereoselective synthesis of β-acetamido esters

The preparation of seven β-acetamido esters, two of which are novel, has been achieved by a one-pot condensation reaction of an araldehyde, ethyl acetoacetate and acetyl chloride in the presence of CeO2 nanoparticles under reflux conditions in acetonitrile. This method provides several advantages including easy workup, excellent yields, short reaction times, diastereoselective synthesis, reusability of the catalyst and low catalyst loading.

Synthesis of Amido Carbonyl Compounds through the Dakin–West Reaction using Lewis Acid Catalysts

The synthesis is described of β-amido carbonyl compounds with enolisable ketones and esters in the presence of aldehyde derivatives and nitrile compounds using Lewis acid catalysts.

One-pot synthesis of β-acetamido ketones using boric acid at room temperature

β-acetamido ketones were synthesized in excellent yields through one-pot condensation reaction of aldehydes, acetophenones, acetyl chloride, and acetonitrile in the presence of boric acid as a solid heterogeneous catalyst at room temperature. It is the first successful report of boric acid that has been used as solid acid catalyst for the preparation of β-acetamido ketones. The remarkable advantages offered by this method are green catalyst, mild reaction conditions, simple procedure, short reaction times, and good-to-excellent yields of products.