No abstract

New pyrazole-, 1,3,4-oxadiazole-, and 1,2,4-triazole-conjugated pyrazolylquinoxalines were synthesized from 4-phenyl-1,5-benzodiazepine-2-thione. The identification of these compounds was carried out using 1 H-and 13 C-NMR, IR, and mass spectrometry.

The title compound, C18H16N4O, is built up from fused six- and five-membered rings linked to a five-membered isoxazole ring and to a six-membered pyridine ring through a CH2 group. The fused-ring system is essentially planar, with a maximum deviation of 0.019 (1) Å. It forms inter­planar angles of 70.03 (7)° with the isoxazole ring and 81.68 (7)° with the pyridine ring; the two latter rings are also planar, the maximum deviations from the mean planes being 0.0028 (15) and 0.0047 (12) Å, respectively. In the crystal, weak inter­molecular non-classical C—H⋯N hydrogen bonds link the mol­ecules, forming a zigzag-like chain parallel to the b axis. A weak intra­molecular C—H⋯N hydrogen bond may help to define the conformation of the mol­ecule.

The di­hydro­quinoxaline ring system of the title mol­ecule, C19H17N3O3, is approximately planar [maximum deviation = 0.050 (2) Å], the dihedral angle between the planes through the two fused rings being 4.75 (8)°. The mean plane through the fused-ring system forms a dihedral angle of 30.72 (5)° with the attached phenyl ring. The mol­ecular conformation is enforced by C—H⋯O hydrogen bonds. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming a three-dimensional network.

In the title compound, C15H14N4, the phenyl and pyrazole rings are essentially coplanar, being twisted relative to each other by a dihedral of only 3.68 (11)°. The benzene ring makes a dihedral angle of 64.47 (11)° with the pyrazole ring. The crystal structure is stabilized by two inter­molecular N—H⋯N hydrogen-bonds, which build a two-dimensional network developing parallel to (100). An intra­molecular N—H⋯N hydrogen bond also occurs.