Hydrogen-bonded chains of rings in methyl 4-[(5-methyl-1<i>H</i>-pyrazol-3-yl)amino]-3-nitrobenzoate and hydrogen-bonded sheets in methyl 1-(5-methyl-1<i>H</i>-pyrazol-3-yl)-1<i>H</i>-benzimidazole-5-carboxylate
作者:Jaime Portilla、Ernesto G. Mata、Manuel Nogueras、Justo Cobo、John N. Low、Christopher Glidewell
DOI:10.1107/s0108270106044611
日期:2007.1.15
Molecules of methyl 4-[(5-methyl-1H-pyrazol-3-yl)amino]-3-nitrobenzoate, C12H12N4O4, (I), exhibit a polarized (charge-separated) structure in the nitroaniline portion. The molecules are linked into chains of edge-fused R-2(2)(16) and R22( 22) rings by a combination of N-H center dot center dot center dot O(carbonyl) and C-H center dot center dot center dot O(nitro) hydrogen bonds. Methyl 1-(5-methyl-1H-pyrazol-3-yl)-1H-benzimidazole-5-carboxylate, C13H12N4O2, (II), which is readily formed from (I) by reduction followed by ring formation, crystallizes with Z' = 2 in the space group P1. Each of the two independent molecular types is linked into sheets of R-4(4)(28) rings by a combination of N-H center dot center dot center dot N and C-H center dot center dot center dot O(carbonyl) hydrogen bonds.
Solution-Phase and Solid-Phase Synthesis of 1-Pyrazol-3-ylbenzimidazoles
The facile solution and solid-phase synthesis of 1-pyrazol-3-ylbenzimidazoles from 4-fluoro-3-nitrobenzoate derivatives and 5(3)-amino-3(5)-subtituted-1 H-pyrazoles is reported. The key step is the unexpected nucleophilic aromatic displacement of the activated fluorine by the exocyclic amino group of the pyrazole ring leading to 4-pyrazolylamino-3-nitrobenzoate derivatives, which are easily converted