Ramesh Yella

It is “2-imino-4-thiazolidinones” and not thiohydantoins as the reaction product of 1,3-disubstituted thioureas and chloroacetylchloride

The products obtained by the reaction of 1,3-disubstituted thioureas with chloroacetylchloride are actually 2-imino-4-thiazolidinone derivatives and not thiohydantoins as previously reported (M. Kidwai, R. Venkataraman and B. Dave, Green. Chem., 2001, 3, 278). A highly efficient method for the preparation of 2-imino-4-thiazolidinones has been achieved from both symmetrical and unsymmetrical thioureas in the absence of base. The reaction gives a regioselective product for unsymmetrical thiourea which is dependent on the pKas of the amines. For unsymmetrical thiourea, regioselective 2-imino-4-thiazolidinone formation takes place with the amine attached to the thiourea having lower pKa as part of the imino component and the amine having higher pKa contributes to the other heterocyclic nitrogen.

Efficient Preparation of Isothiocyanates From Dithiocarbamates Using Bromineless Brominating Reagent

For the first time, the crystal structure of a ditribromide reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been determined. Utilizing this thiophilic bromineless brominating agent EDPBT, highly useful synthetic intermediates (alkyl and aryl isothiocyanates) have been achieved directly from dithiocarbamates. EDPBT can be easily prepared from readily available reagents. It has been used as a thiophilic reagent, and its thiophilicity dominates over its brominating ability for substrates amenable to bromination. This is a sustainable process for the preparation of isothiocyantes because the spent reagent can be recovered, regenerated, and reused.

Efficient one-pot preparation of bisalkyl xanthogen disulfides from alcohols

An efficient one-pot synthetic procedure for the preparation of bisalkyl xanthogen disulfides is achieved via oxidation of the in situ generated xanthate salt in an aqueous condition using half an equivalent of molecular iodine in one pot.

Bromineless Bromine as an Efficient Desulfurizing Agent for the Preparation of Cyanamides and 2-Aminothiazoles from Dithiocarbamate Salts

Abstract In a one-pot procedure, bromineless brominating reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been used as a desulfurizing agent in the preparation of organic cyanamides and substituted thiazoles starting from dithiocarbamic acid salts. In this approach, alkyl/aryl isothiocyantes were first obtained by the desulfurization of dithiocarbamic acid salts with EDPBT. The in situ–generated isothiocyanates reacts with an aqueous ammonia, forming alkyl or aryl thioureas, which on subsequent oxidative desulfurization with EDPBT led to the formation of corresponding cyanamides in good yields. Alternatively, an efficient one-pot synthesis of substituted thiazoles has been achieved by the condensation of the in situ–generated 1-aryl thioureas with the in situ–generated α-bromoketones from ketones, again using EDPBT. The reagent EDPBT can be easily prepared from the readily available reagents. Desulfurizing ability dominates over its brominating ability for substrates amenable to bromination.

It is ‘thiazolidine-2,4-dione’ and not thiohydantoins as the reaction product of monosubstituted thioureas and chloroacetylchloride

The reaction products of monosubstituted phenylthioureas with chloroacetylchloride in a polyethylene glycol (PEG-400) medium and K2CO3 as base/catalyst at an elevated temperature are exclusively thiazolidine-2,4-diones and not thiohydantoins as has been reported. The core unit thiazolidine-2,4-dione is essentially derived from chloroacetylchloride and the thioamidic part of the phenylthiourea. The scope of this unprecedented transformation has been evaluated with electron-rich and electron-poor phenylthioureas.