Hypervalent Iodine(III)-Mediated Regioselective N-Acylation of 1,3-Disubstituted Thioureas

Abstract

Reaction of asymmetrical 1,3-disubstituted thioureas with diacetoxyiodobenzene (DIB) produces regioselectively N-acetylurea in shorter time. Regioselectivity is dependent on the pKa's of the amine attached to the thiourea moiety with acylation taking place toward the amine having a lower pKa. This is the first example of DIB being employed as an N-acetylating agent. A mechanism for this novel transformation is also proposed. Mild reaction conditions, shorter reaction times, high efficiencies, environmentally benign methods, and facile isolation of the desired product make the present methodology a most suitable alternative.

A novel sensing capabilities and structural modification from thiourea to urea derivative by Hg(ClO4)2: Selective dual chemodosimeter for Hg2+ and F− ions

“…First, in the Hg 2+ sensing mechanism of L1, the Hg 2+ induces the desulfurization reaction, converting the theory derivative to a carbodiimide intermediate and followed by a perchlorate anion attack gives urea derivative [62][63][64][65]. The suggested mechanism for urea formation by the 1 equiv.…”

“…Herein, we report a rhodamine 6G phenylthiourea Page 6 of 44 A c c e p t e d M a n u s c r i p t 6 derivative (L1) as a simple and new chemosensor for Hg 2+ , which exhibits highly selective, dual selectivity and a rapid spectroscopic response towards Hg 2+ and F -in acetonitrile. Our design is based on the well-known reactions of thiourea derivatives with amines to yield urea, in the course of desulfurization, reacts with the intermediary diphenylcarbodiimide derivatives in the presence of Hg 2+ ions, as depicted in Scheme 1 [62][63][64][65]. First, we chose the general mercury-promoted desulfurization reaction as the recognition event to impart high selectivity based on the strong thiophilic affinity of Hg 2+ ions.…”

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

“…Recently we have taken advantage of the desulfurizing ability of a hypervalent iodine reagent, diacetoxyiodobenzene (DIB), for the oxidative N-acylation of 1,3-disubstituted thiourea, [1] in the preparation of isothiocyanates and for the construction of heterocycles [2a] and cyanamides, [2b] from dithiocarbamate salts. However, methods using a hypervalent iodine reagent are efficient but not economically viable when applied to large-scale reactions.…”

A convenient one-pot synthesis of amines from aldoximes mediated by Koser’s reagent

“…5 Our group has explored the thiophilicity of hypervalent iodine(III) reagent, (diacetoxyiodo)benzene (DIB), for various useful organic transformations. These include the preparation of N-acylureas from 1,3-disubstituted thioureas, 6 isothiocyanates, 7 cyanamides 8 and various heterocycles 7 from dithiocarbamic acid salts by an oxidative desulfurization strategy. Very recently, we have reported the oxidation of aldoximes to N-acetoxy or N-hydroxy amides mediated by hypervalent iodine(III) reagent DIB or HTIB.…”