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Facile synthesis of phthalidyl fused spiro thiohydantoins through silica sulfuric acid induced oxidative rearrangement of ninhydrin adducts of thioureas
S. Mandal,
Published in Elsevier Ltd
Volume: 76
Issue: 2
A one-pot three-component sequential synthetic protocol produces structurally and biologically important phthalidyl fused spiro N,N′-disubstituted thiohydantoins from readily available aromatic isothiocyanates, primary amines and ninhydrin. In this three-step synthesis while the initial two steps are catalyst-free, in the final step silica sulfuric acid (SSA) induces an oxidative rearrangement in [3.3.0]-bicyclic 1,2-diol adducts of ninhydrin and thioureas under solvent-free condition to generate the final products spiro-fused thiohydantoins. The adequate acidity of SSA in cooperation with moderate oxidizing property promotes a facile oxidative rearrangement in 1,2-diol intermediates to produce the spiro-fused thiohydantoins with diverse functionalities. Easy recyclability of SSA, good to excellent yield of the products, wider substrate scope, shorter reaction time, solvent-free two steps out of three and high atom economy make this method attractive and practicable. © 2019 Elsevier Ltd
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JournalData powered by TypesetTetrahedron
PublisherData powered by TypesetElsevier Ltd