Redetermined structure of oxaline: absolute configuration using Cu Kα radiation

In the title compound, C(24)H(25)N(5)O(4), the stereogenic C atom bonded to three N atoms and one C atom has an S configuration and its directly bonded neighbour has an R configuration. An intra-molecular N-H⋯O hydrogen bond supports the near coplanarity of the two C(3)N(2)-five-membered rings [dihedral angle = 5.64 (10)°]. In the crystal, mol-ecules are linked by N-H⋯N hydrogen bonds, forming a C(8) chain propagating in [001]. The chains are connected by C-H⋯O inter-actions, generating a three-dimensional network. The previous study [Nagel et al. (1974 ▶). Chem. Commun. pp. 1021-1022] did not establish the absolute structure and no atomic coordinates were published or deposited.