Facile synthesis of phthalidyl fused spiro thiohydantoins through silica sulfuric acid induced oxidative rearrangement of ninhydrin adducts of thioureas was written by Mandal, Subhro;Pramanik, Animesh. And the article was included in Tetrahedron in 2020.Electric Literature of C7H3Cl2NS This article mentions the following:
A one-pot three-component sequential synthetic protocol produces structurally and biol. 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. In the experiment, the researchers used many compounds, for example, 2,4-Dichlorophenylisothiocyanate (cas: 6590-96-1Electric Literature of C7H3Cl2NS).
2,4-Dichlorophenylisothiocyanate (cas: 6590-96-1) belongs to organic chlorides. Organic chlorides can cause corrosion in pipelines, valves and condensers, and cause catalyst poisoning. The hydrocarbon processing industry (HPI) and others are affected by damage caused by these substances. Aryl chlorides may be prepared by the Friedel-Crafts halogenation, using chlorine and a Lewis acid catalyst.Electric Literature of C7H3Cl2NS
Referemce:
Chloride – Wikipedia,
Chlorides – an overview | ScienceDirect Topics