Crystal structures of pure 3-(4-bromo-2-chlorophenyl)-1-(pyridin-4-yl) benzo [4, 5] imidazo [1, 2-d][1, 2, 4] triazin-4 (3H)-one and contaminated with 3-(4-bromophenyl)-1 …

The side product of the cyclocondensation reaction between ethyl benzimidazole-2-carboxylate and the nitrile imine of the corresponding hydrazonyl chloride, C20H11BrClN5O, crystallized in two crystal forms. Form (1) is a co-crystal of the target compound (without any chlorine substituent) and a side product containing a Cl atom in position 2 of the bromophenyl group, C20H12BrN5O·0.143C20H11BrClN5O. (2) contains the pure side product. The slightly different conformation of the ring systems leads to a different packing of (1) and (2), but both crystal structures are dominated by π–π interactions

Efficient Synthesis and X-ray Structure of [1,2,4]Triazolo[4,3-a]pyridines via Oxidative Cyclization Using N-Chlorosuccinimide (NCS)

Triazolopyridines are a family of compounds that, owing to their biological activity, have many pharmaceutical applications. In this study, 3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine and 6-bromo-3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine were synthesized by using the chlorinated agent NCS for hydrazones under very mild conditions. The characterization of these compounds was achieved by 1H NMR, 13C NMR, FTIR, MS and X-ray diffraction. The compound 3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine was crystallized in the monoclinic space group P 21/c with a = 15.1413(12), b = 6.9179(4), c = 13.0938(8) Å, β = 105.102(6)°, V = 1324.16(16)Å3, Z = 4, and R = 0.0337. Also compound 6-bromo-3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine was crystallized in the monoclinic space group P 21/c with a = 14.3213(11), b = 6.9452(4) (4), c = 12.6860(8)Å, β = 100.265(6)°, V = 1241.62(14)Å3, Z = 4, and R = 0.0561

Crystal structures of pure 3-(4-bromo-2-chlorophenyl)-1-(pyridin-4-yl)benzo[4,5]imidazo[1,2-d][1,2,4]triazin-4(3H)-one and contaminated with 3-(4-bromophenyl)-1-(pyridin-4-yl)benzo[4,5]imidazo[1,2-d][1,2,4]triazin-4(3H)-one

The side product of the cyclocondensation reaction between ethyl benzimidazole-2-carboxylate and the nitrile imine of the corresponding hydrazonyl chloride, C20H11BrClN5O, crystallized in two crystal forms. Form (1) is a co-crystal of the target compound (without any chlorine substituent) and a side product containing a Cl atom in position 2 of the bromophenyl group, C20H12BrN5O·0.143C20H11BrClN5O. (2) contains the pure side product. The slightly different conformation of the ring systems leads to a different packing of (1) and (2), but both crystal structures are dominated by π–π interactions

1-(Pyridin-4-yl)-3-(2,4,6-trichlorophenyl)benz[4,5]imidazo[1,2-d][1,2,4]triazin-4(3H)-one

In the title compound, C20H10Cl3N5O, the 13-membered ring system makes dihedral angles of 78.64 (9)° with the trichlorophenyl ring and 62.60 (10)° with the pyridine ring. The crystal packing is dominated by π–π interactions between the 13-membered ring systems [centroid–centroid distance = 3.6655 (11)°]