“On-water” synthesis of thioxoimidazolidinone-isatin/ninhydrin conjugates, followed by temperature-induced dehydration by a ZnMnO3@Ni(OH)2 nano-catalyst

Abstract

A novel and efficient “on water” mediated one-pot ZnMnO₃@Ni(OH)₂ catalyzed straight-forward synthesis of 3-hydroxy-3-(3-methyl-5-oxo-2-thioxoimidazolidin-4-yl)oxindole via a thiazolidinedione–isatin conjugate has been explored. Concurrently, temperature-regulated dehydrated adducts of 3-hydroxy-3-(3-methyl-5-oxo-2-thioxoimidazolidin-4-yl)oxindole were also demonstrated. The use of a recyclable ZnMnO₃@Ni(OH)₂ nano-catalyst in the aqueous medium makes the protocol sustainable and green. The synthesis of ZnMnO₃@Ni(OH)₂ nanopowder has been meticulously characterized using powdered XRD, HRTEM, EDX and BET analyses. Moreover, the choice of readily available and readily made starting materials under mild and operationally simple reaction conditions is the major advantage of this strategy. The catalyst exhibits high water compatibility and demonstrates the ability to be recycled and reused for a minimum of eight cycles. Through a standard leaching experiment, it was confirmed that the reaction proceeded heterogeneously with this recyclable catalyst.