Hydrogen-bonded dimers in 3-amino-4-anilino-1H-isochromen-1-one and a hydrogen-bonded sheet in 3-amino-4-[methyl(phenyl)amino]-1H-isochromen-1-one
Fecha de publicación: 01/07/2013

The molecules of 3-amino-4-anilino-1H-isochromen-1-one, C15H12N2O2, (I), and 3-amino-4-[methyl(phenyl)amino]-1Hisochromen-1-one, C16H14N2O2, (II), adopt very similar conformations, with the substituted amino group PhNR, where R = H in (I) and R = Me in (II), almost orthogonal to the adjacent heterocyclic ring. The molecules of (I) are linked into cyclic centrosymmetric dimers by pairs of N—H…O hydrogen bonds, while those of (II) are linked into complex sheets by a combination of one three-centre N—H…(O)2 hydrogen bond, one two-centre C—H…O hydrogen bond and two C—H…Pi(arene) hydrogen bonds.

A concise and efficient synthesis of amino-substituted (1H-benzo[d ]imidazol-1-yl)pyrimidine hybrids: synthetic sequence and the molecular and supramolecular structures of six examples
Fecha de publicación: 13/08/2019

A concise and efficient synthesis of a series of amino-substituted benzimidazole–pyrimidine hybrids has been developed, starting from the readily available N4-(2-aminophenyl)-6-methoxy-5-nitrosopyrimidine-2,4-diamine. In each of N5-benzyl-6-methoxy-4-(2-phenyl-1H-benzo[d]imidazol-1-yl)pyrimidine-2,5-diamine, C25H22N6O, (I), 6-methoxy-N5-(4-methoxybenzyl)-4-[2-(4-methoxyphenyl)-1H-benzo[d]imidazol-1-yl]pyrimidine-2,5-diamine, C27H26N6O3, (III), 6-methoxy-N5-(4-nitrobenzyl)-4-[2-(4-nitrophenyl)-1H-benzo[d]imidazol-1-yl]pyrimidine-2,5-diamine, C25H20N8O5, (IV), the molecules are linked into three-dimensional framework structures, using different combinations of N—H…N, N—H…O, C—H…O, C—H…N and C—H…. hydrogen bonds in each case. Oxidative cleavage of 6-methoxy-N5-(4-methylbenzyl)-4-[2-(4-methylphenyl)-1H-benzo-[d]imidazol-1-yl]pyrimidine-2,5-diamine, (II), with diiodine gave 6-methoxy-4-[2-(4-methylphenyl)-1H-benzo[d]imidazol-1-yl]pyrimidine-2,5-diamine, which crystallized as a monohydrate, C19H18N6OH2O, (V), and reaction of (V) with trifluoroacetic acid gave two isomeric products, namely N-{5-amino-6-methoxy-6-[2-(4-methylphenyl)-1H-benzo[d]imidazol-1-yl]pyrimidin-2-yl}-2,2,2-trifluoroacetamide, which crystallized as an ethyl acetate monosolvate, C21H17F3N6O2.C4H8O2, (VI), and N-{2-amino-6-methoxy-4-[2-(4-methylphenyl)-1Hbenzo[d]imidazol-1-yl]pyrimidin-5-yl}-2,2,2-trifluoroacetamide, which crystallized as a methanol monosolvate, C21H17F3N6O2.CH4O, (VIIa). For each of (V), (VI) and (VIIa), the supramolecular assembly is two-dimensional, based on different combinations of O—H…N, N—H…O, N—H…N, C—H…O and C—H…. hydrogen bonds in each case. Comparisons are made with some related structures.

A concise synthesis of a highly substituted 6-(1H-benzimidazol-1-yl)-5-nitrosopyrimidin-2- amine: synthetic sequence and the molecular and supramolecular structures of one product and two intermediates
Fecha de publicación: 08/07/2018

A concise and efficient synthesis of 6-benzimidazolyl-5-nitrosopyrimidines has been developed using Schiff base-type intermediates derived from N4-(2-aminophenyl)- 6-methoxy-5-nitrosopyrimidine-2,4-diamine. 6-Methoxy-N4-{2-[(4-methylbenzylidene) amino]phenyl}-5-nitrosopyrimidine-2,4-diamine, (I), and N4-{2-[(ethoxymethylidene)amino]phenyl}-6-methoxy-5-nitrosopyrimidine-2,4-diamine, (III), both crystallize from dimethyl sulfoxide solution as the 1:1 solvates C19H18N6O2.C2H6OS, (Ia), and C14H16N6O3.C2H6OS, (IIIa), respectively. The interatomic distances in these intermediates indicate significant electronic polarization within the substituted pyrimidine system. In each of (Ia) and (IIIa), intermolecular N—H…O hydrogen bonds generate centrosymmetric four molecule aggregates. Oxidative ring closure of intermediate (I), effected using ammonium hexanitratocerate(IV), produced 4-methoxy-6-[2-(4-methylphenyl- 1H-benzimidazol-1-yl]-5-nitrosopyrimidin-2-amine, C19H16N6O2, (II) [Cobo et al. (2018). Private communication (CCDC 1830889). CCDC, Cambridge, England], where the extent of electronic polarization is much less than in (Ia) and (IIIa). A combination of N—H N and C—H O hydrogen bonds links the molecules of (II) into complex sheets.

Synthesis of new 1,2-diaryl[2]benzopyrano[3,4-d]imidazol-5(1H)-one derivatives mediated by ceric ammonium nitrate
Fecha de publicación: 12/07/2017

In summary, we have implemented a simple two-step methodology for obtaining a new series of 1,2-diaryl[2]benzopyrano[3,4-d]imidazol-5(1H)-one derivatives 6a–j in acceptable to good yields through a carbon-nitrogen bond-forming reaction by using CAN as key mediator. Which constitutes a simple way to form this interesting tricyclic system that fused isocoumarin and imidazole rings, what is of interest to develop new bioactive derivatives. The role of the CAN is important since it acts as Lewis catalyst, as it was proposed in the mechanism.