In the title compound, C(23)H(19)N(3)O(2), the dihedral angles formed by the pyrazolone ring with the three benzene rings are 30.91 (6), 60.96 (4) and 57.01 (4)°. The ligand is in the enamine-keto form and its structure is stabilized by an intra-molecular N-H⋯O hydrogen bond. In the crystal, O-H⋯N hydrogen bonds link mol-ecules into chains parallel to [01-1].

In the title compound, C19H17Cl2N3O2, the amide group is planar and, through N-H⋯O hydrogen bonding to an adjoining mol-ecule, forms dimers of the R2(2)(10) type. As a result of steric repulsion, the amide group is rotated with respect to both the dichloro-phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings, making dihedral angles of 71.63 (11) and 57.93 (10)°, respectively. The dihedral angle between...

This study focused on the mechanistic interpretation of ex vivo oxidation of a candidate drug in blood plasma samples. An unexpected lipid peroxide-mediated epoxidation followed by a dramatic rearrangement led to production of a five-membered oxazole derivative from the original six-membered pyrazinone-carboxamide core of a human neutrophil elastase inhibitor, 6-(1-(4-cyanophenyl)-1H-pyrazol-5-...

The title compound, C(21)H(23)N(3)O, exists in an enamine-keto form with the amino group involved in an intra-molecular N-H⋯O hydrogen bond. The dihedral angle between the phenyl rings is 73.59 (6)°. The five-membered ring is nearly planar, the largest deviation being 0.0004 (7) Å, and makes dihedral angles of 4.81 (6) and 69.81 (5)° wth the phenyl rings. In the crystal, pairs of weak C-H⋯O int...