Synthetic Studies toward Aryl-(4-aryl-4H-[1,2,4]triazole-3-yl)-amine from 1,3-Diarylthiourea as Urea Mimetics

Abstract

A thiophile promoted synthesis of di-substituted 4H-[1,2,4]triazole-3-yl-amines as urea mimetics from the corresponding 1,3-disubstituted thioureas has been studied and the scope and limitations of this reaction are presented. The reaction proceeds through the formation of a carbodiimide, followed by a sequential addition-dehydration with acyl hydrazides. 1,3-Branched dialkylthioureas result in the formation of the corresponding ureas. The electronic and steric effect of the substitution on the phenyl rings of the 1,3-diarylthioureas play an important role in the formation of the intermediary carbodiimde and the direction of the subsequent ring closure of the N-acyl hydrazide adduct.

Highly Sensitive and Fast Responsive Fluorescence Turn‐On Chemodosimeter for Cu2+ and Its Application in Live Cell Imaging

“…These results indicate a distinct recognition mechanism of 4 towards Cu 2 + as compared to that of its response to Hg 2 + . Recently, Chorev et al [26] have reported that dialkyl-substituted thioureas undergo rapid formation of the intermediate carbodiimide in the presence of HgA C H T U N G T R E N N U N G (OAc) 2 (Scheme 4). Thus, we can deduce a recognition mechanism of 4 towards Hg 2 + as follows (Scheme 3): a) In the presence of less than one equiv Hg 2 + , 4 undergoes an irreversible desulfurization reaction and is thereby converted into an intermediate carbodiimide 7, in accordance with the observations of Chorev et al [26] This is further confirmed by the appearance of a peak at m/z 538.2 (calcd for 538.3) assigned to [7+H] + in the ESI mass spectrum of a colorless and weakly fluorescent mixture of 4 with 0.5 equiv of Hg 2 + in ethanol (see Figure S10 in the Supporting Information).…”

5-amino-3,4-dihydro-2h-1,2,4-triazole-3-thiones. synthesis and chemosensor properties

“…In the case of compounds 4d,f, the NH group signal is found at 9.10-9.20 ppm as a singlet. Such a downfield shift is characteristic for some derivatives of N-aryl-N-(1,2,4-triazol-3-yl)amines [13]. The structure of intermediates 3 was demonstrated for thiosemicarbazide 3e, which could be separated and characterized.…”

“…Derivatives of 1,2,4-triazole have found common use in medicine [1-3] and as efficient corrosion inhibitors [4], catalysts [5], ligands [6], and chemosensors [7], Various pathways and methods exist for the synthesis and modification of both 1,2,4-triazole [8][9][10] and its 3-thio derivatives [11][12][13]. Greatest interest is found for one-and two-step methods for the preparation of similar structures.…”

1,3-Disubstituted Thioureas: Versatile Building Blocks for the Construction of Heterocycles

“…13 When 1,3-disubstituted thiourea was reacted with formic hydrazide and mercury(II) acetate as thiophile, the reaction mixture produced acyl hydrazide adduct, which was cyclized to the corresponding [1,2,4]triazole under acidic conditions. …”