Crystal structure of 1'-ethyl-spiro[chroman-4,4'-imidazolidine]-2',5'-dione: a hydantoine derivative.

The title compound, C13H13N2O3, a hydantoin derivative, crystallized with two mol-ecules (A and B) in an asymmetric unit. In mol-ecule A, the imidazolidine ring is twisted about the C-N bond involving the spiro C atom, while in mol-ecule B this ring is flat (r.m.s. deviation = 0.010 Å). The pyran rings in both mol-ecules have distorted half-chair conformations. The mean plane of the imidazolidine ring is inclined to the aromatic ring of the chroman unit by 79.71 (11)° in mol-ecule A and 82.83 (12)° in mol-ecule B. In the crystal, pairs of N-H⋯O hydrogen bonds link the individual mol-ecules to form A-A and B-B inversion dimers. The dimers are linked via N-H⋯O and C-H⋯O hydrogen bonds, forming sheets lying parallel to the bc plane, viz. (011). Within the sheets, the A and B mol-ecules are linked by C-H⋯π inter-actions.