The X-ray structures of three simple heterocyclic compounds have been obtained for the first time. Structures both 3-acetyloxazolidin-2-one 1 and its unsaturated analogue 3-acetyloxazolin-2-one 3 show a planar imide nitrogen with exocyclic C=O oriented anti to ring N–C(=O) bond negligible intermolecular interactions, pattern consistent previously reported analogues. In contrast parent NH hetero...

In the title compound, C(12)H(13)N(3)O(2)S, the oxazolidin ring displays an envelope conformation. The dihedral angle between the benzimidazole ring and the 1,3-oxazolidin-2-one mean plane is 69.85 (13)°. In the crystal, mol-ecules are linked by inter-molecular N-H⋯N hydrogen bonds, forming a chain parallel to the b axis.

In the title compound, C(9)H(8)N(2)O(4), the indolin-2-one ring system is substanti-ally planar [maximum deviation = 0.0353 (15) Å]. In the crystal structure, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds are responsible for the formation of a three-dimensional network.

In the title compound, C(21)H(23)N(3)O(2), the indolin-2-one group is essentially planar, with a maximum deviation of 0.016 (2) Å for the N atom, and makes a dihedral angle of 84.38 (14)° with the benzene ring. The =N-N(H)-C(=O)-C- torsion angle is 0.9 (3)°. In the crystal, mol-ecules are linked into a three-dimensional network via N-H⋯O and C-H⋯O hydrogen bonds. In addition, a C-H⋯π inter-acti...

In the title compound, C(20)H(21)NO(2), the benzyl group and the oxazolidin-2-one unit are each essentially planar, with maximum deviations of 0.026 (2) and 0.031 (2) Å, respectively. The dihedral angle between the phenyl ring and the oxazolidin-2-one unit is 69.25 (2)°. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O and C-H⋯π inter-actions.