Selective functional group transformation using guanidine: the conversion of an ester group into an amide in vinylogous ester–aldehydes of imidazole (original) (raw)
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Synthesis of the Guanidine Derivative: N-{(7-(4,5-Dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)aminomethylene}benzamide
2021
The guanidine derivative N-{[(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)amino](phenylamino)methylene}benzamide (3) has been obtained by the reaction of one measure of N-{[7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene]carbamothioyl}benzamide (2) with one measure of aniline in the presence of mercury(II) chloride and triethylamine in anhydrous dimethylformamide. The structure of product 3 was confirmed by 1H and 13C-NMR, infrared spectroscopy, and elemental analysis.
Efficient synthesis of imidazole and pyrimidine derivatives
Chemistry of Heterocyclic Compounds, 2020
Amidines are known reagents in some synthetic methods for obtaining heterocyclic compounds as well as they are used as suitable reagents in numerous cycloaddition processes. An example of their application is the synthesis of pyrimidines and imidazoles shown by Vidal and coauthors. 1 Also, a new efficient and convenient approach was proposed to the synthesis of pyrimidines by Cu-catalyzed and 4-HO-TEMPO-mediated [3+3] annulation of commercially available amidines with saturated ketones. 2 On the other hand, diazaheterocyclic compounds are interesting from various scientific aspects 3 and have a significant potential as modern functional materials, 4 as well as they could be considered as objects which have a significant interest from the point of view of biological activity. 5 The aim of the work was to develop on the basis of known procedures 6 a method for the synthesis of N,N'-unsubstituted α-aminoamidines and ways for their further modification to synthesize new promising imidazole-and pyrimidine-containing compounds. We proposed and optimized a convenient and affordable pathway for the synthesis of previously undescribed α-aminoamidines 4a-e starting from N-protected amino-nitriles 1a-e, which can be easily obtained by described methods (Scheme 1). 7,8 The key stage of the approach is a procedure of hydrogenation of O-acetyl-substituted amino-oximes 3a-e in the presence of palladium catalyst. 9,10 It should be noted, that our attempts to perform direct reduction of aminooximes 2a-e to aminoamidines 4a-e were unsuccessful, though such transformations for amidines had been described in literature earlier. 11-16 Therefore, we carried out preliminary O-acylation of compounds 2a-e by acetic anhydride. A convenient and affordable synthetic pathway for obtaining new α-aminoamidines starting from aminonitriles is proposed. The α-aminoamidines obtained can be applied as substrates for further transformations and synthesis of imidazole-and pyrimidine-containing building blocks.
Synthesis and Characterization of Some New 4-Methyl-5-Imidazole Carbaldehyde Derivatives
Journal of the Turkish Chemical Society Section A: Chemistry, 2019
Imidazole is a common and important heterocyclic fragment of many biologically important molecules. 5-imidazole-carbaldehydes containing mono- (N-1) methyl (or aryl) analogs are commonly used as building blocks in medical chemistry. In this study, starting from 4-methyl-1H-imidazole-5-carbaldehyde, the N-1 atom of the imidazole ring is derived with different alkyl groups. In addition, both N atoms of the starting imidazole-carbaldehyde were methylated to give 5-carbaldehyde-1,3,4-trimethyl-3-imidazolium salt. The salt which possess quite reactive carbaldehyde group could be used as a precursor for synthesis of other imidazolium derivatives. Furthermore, 4-methyl-5-imidazole carbaldehyde was converted into the benzoxazole, benzothiazole and benzoimidazole by a two-step reaction over the aldehyde group. These new compounds could display some biological activities.
An efficient synthesis of tetrasubstituted imidazoles from N-(2Oxo)-amides
Tetrahedron Letters, 1998
N-(2-Oxo)-amides were efficiently converted to tri- and tetra- substituted imidazoles under neutral reaction conditions upon treatment with neat ammonium trifluoroacetate.N-(2-Oxo)-amides were efficiently converted to tri- and tetra- substituted imidazoles under neutral reaction conditions upon treatment with neat ammonium trifluoroacetate.
Functionalization of imidazole N-oxide: a recent discovery in organic transformations
Beilstein Journal of Organic Chemistry, 2022
Nowadays heterocyclic compounds are widely used in medicinal chemistry and industry to develop life-saving drugs and medicines. Imidazole is one of the pharmacologically important heterocyclic motifs found in widely used and well-known medicines and bioactive molecules. The applications of imidazole derivatives displaying various biological activities, motivated researchers for the development of more potent and significant drugs containing imidazole moieties. The formation of imidazole derivatives can be achieved using imidazole N-oxide as starting material. In this review, the scope of substrates and reaction mechanisms of various synthetic approaches using imidazole N-oxides as substrates are summarized so that the chemists, researchers, and pharmaceutical industries find its effectiveness in near future for the synthesis of potent, novel, and non-toxic drug molecules.
ChemistrySelect, 2020
A new synthetic protocol for the synthesis of 1H-benzotriazole-1-carboximidamides starting from aryl amines in presence of acylbenzotriazole has been reported. The versatile guanylating agents could be an efficient synthetic tool for the synthesis of various guanidines. The present approach enables all possible variations of the substituents at different positions of the products. Single crystal of compound 4e was obtained by recrystallization from suitable solvent systems for X-ray and DFT studies. The reaction goes faster and yields more product with higher purity when Cbz protected aminoacyl benzotriazole used instead of aryl benzotriazole for the synthesis of the 1H-benzotriazole-1-carboximidamides. Computational studies were carried out to elucidate the energy profile and transition states to support the experimental data. Short reaction time, simple workup, high yields, and mild conditions are the key advantages of this protocol.
A Safe and Efficient Synthetic Route to a 2,5-Dimethyl-1-aryl-1 H -imidazole Intermediate
Organic Process Research & Development, 2011
An optimized route to an iodo-imidazole intermediate in the synthesis of 4-ethynyl-2,5-dimethyl-1aryl-1H-imidazoles (6) was devised. Important data for the optimization work was obtained by carrying out a DOE study to gain understanding of the parameters that affect the key intramolecular cyclization to build the imidazole ring. Additional information on the reaction mechanism of this step was obtained by carrying out a flow NMR experiment. In order to complete the proof of concept, the iodoimidazole intermediate was converted to two ethynyl imidazoles (6a, b) using metal-catalyzed reactions.