- Ultrasound assisted, VOSO4 catalyzed synthesis of 4-thiazolidinones: Antimicrobial evaluation of indazole-4-thiazolidinone derivatives
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A simple and expedient multicomponent protocol was developed to synthesize 4-thiazolidinones by employing VOSO4 as a catalyst under ultrasonic irradiation. The significant features of this protocol includes shorter reaction time, high yields, low catalyst loading, and also the catalyst can be recovered and reused up to next four cycles without significant loss in catalytic activity. All the synthesized novel indazole compounds were evaluated for their antibacterial and anti-biofilm activities. Compounds 9n, 9o and 9q showed promising activity (MIC value of 3.9 μg/mL) against K. planticola (MTCC 530). They also exhibited significant bactericidal activity against K. planticola (MTCC 530) (MBC value of 15.6 μg/mL). Additionally, 9n, 9o and 9q inhibited biofilm formation (IC50 values ranging between 20.28–20.79 μg/mL) in this organism.
- Angapelly, Srinivas,Sri Ramya,SunithaRani, Routhu,Kumar, C. Ganesh,Kamal, Ahmed,Arifuddin, Mohammed
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supporting information
p. 4632 - 4637
(2017/11/10)
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- 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
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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 HClO 4-SiO2 > TfOH-SiO2 ? H2SO 4-SiO2 > p-TsOH-SiO2 > MsOH-SiO 2 ~ HBF4-SiO2 > TFA-SiO2 ~ HOAc-SiO2. The better catalytic potential of HClO 4-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-SiO 2 ? HClO4-K10 > HClO4-KSF > HClO 4-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.
- Kumar, Dinesh,Sonawane, Mukesh,Pujala, Brahmam,Jain, Varun K.,Bhagat, Srikant,Chakraborti, Asit K.
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p. 2872 - 2884
(2013/10/08)
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