Supported protic acid-catalyzed synthesis of 2,3-disubstituted thiazolidin-4-ones: enhancement of the catalytic potential of protic acid by adsorption on solid supports
作者:Dinesh Kumar、Mukesh Sonawane、Brahmam Pujala、Varun K. Jain、Srikant Bhagat、Asit K. Chakraborti
DOI:10.1039/c3gc41218k
日期:——
The catalytic potential of various protic acids has been assessed for the one pot tandem condensation–cyclisation reaction involving an aldehyde, an amine, and thioglycolic acid to form 2,3-disubstituted thiazolidin-4-ones. The catalytic potential of the various protic acids that follows the order TfOH > HClO4 > H2SO4 ∼ p-TsOH > MsOH ∼ HBF4 > TFA ∼ AcOH is improved significantly by adsorption on solid supports, in particular using silica gel (230–400 mesh size), with the resulting relative catalytic potential following the order HClO4–SiO2 > TfOH–SiO2 ≫ H2SO4–SiO2 > p-TsOH–SiO2 > MsOH–SiO2 ∼ HBF4–SiO2 > TFA–SiO2 ∼ HOAc–SiO2. The better catalytic potential of HClO4–SiO2 as compared to that of Tf–SiO2, although TfOH is a stronger protic acid than HClO4, can be rationalised through a transition state model depicting the interaction of the individual protic acid with SiO2. The catalytic efficiency of HClO4 adsorbed on various solid supports was in the order HClO4–SiO2 ≫ HClO4–K10 > HClO4–KSF > HClO4–TiO2 ∼ HClO4–Al2O3. The catalytic system HClO4–SiO2 is compatible with different variations of aldehydes (aryl/heteroaryl/alkyl/cycloalkyl) and the amines (aryl/heteroaryl/arylalkyl/alkyl/cycloalkyl) affording the desired 2,3-disubstituted thiazolidin-4-ones in 70–87% yields (43 examples). The electronic and the steric factors associated with the aldehydes and the amines provide a handle for selective thiazolidinone formation and were found to be dependent on the extent of imine formation. No significant amount of thiazolidinone formation took place during the reaction of the preformed amide (synthesised from the amine and thioglycolic acid) with benzaldehyde suggesting that the reaction proceeds through the initial reversible imine formation followed by cyclocondensation of the preformed imine with thioglycolic acid, the reversible imine formation being the determining step to control selectivity of thiazolidinone formation in competitive environments. The feasibility of a large scale reaction and catalyst recycling/reuse is demonstrated.
Silica chloride (SiO<sub>2</sub>-Cl) catalyzed one pot synthesis of 2,3-disubstituted-thiazolidin-4-one
作者:Kunal M. Gokhale、Vikas N. Telvekar
DOI:10.1080/00397911.2020.1741641
日期:2020.5.2
Abstract In this paper, we report one-pot, three-component cyclo condensation of an aldehyde, an amine and thioglycolic acid to form 2,3-disubstituted-thiazolidin-4-one by using supported protic acid (Silica Chloride: SiO2-Cl) catalyst. The catalyst SiO2-Cl is compatible with a variety of aldehydes (aryl/heteroaryl) and the aromatic amines affording 2,3-disubstituted-thiazolidin-4-one analogs in 72–89%
A visible-light-induced, one-pot mild and efficient, multicomponent-tandem synthesis of diversified 1,3-thiazolidin-4-ones under catalyst and solvent-free conditions is reported. Here, visible-light, an ideal source of energy, has been used as photochemical activator to generate CN and CS bonds under radical mechanistic pathway from aromatic amines, aldehydes and thioglycolic acid. The reported methodology
An efficient three-component synthesis of 1,3-thiazolidin-4-ones is described by one-pot condensation of aldehydes, aniline and thioglycolic acid with nano-CdZr4(PO4)6 as a robust heterogeneouscatalyst under ultrasonic irradiation. Use of simple and readily available starting materials, experimental simplicity, applying the sonochemical methodology as an efficient method and innocuous means of activation
Preparation and characterization of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>/APTPOSS core-shell composite nanomagnetics as a novel family of reusable catalysts and their application in the one-pot synthesis of 1,3-thiazolidin-4-one derivatives
作者:Javad Safaei-Ghomi、Seyed Hadi Nazemzadeh、Hossein Shahbazi-Alavi
DOI:10.1002/aoc.3520
日期:2016.11
The inorganic–organic hybrid polyhedral oligomeric silsesquioxane magneticnanoparticles were used as an efficient new heterogeneous catalyst for the one‐pot three‐component synthesis of 1,3‐thiazolidin‐4‐ones under solvent‐free conditions. Moreover, these nanoparticles could be easily separated using an external magnet and then reused several times without significant loss of catalytic activity. Copyright