Crystal structure of cyclic dehydroaminoacid derivatives: II. An (E)-5(4H)-oxazolone

Abstract

Abstract The crystal and molecular structures of an “E” 5(4H)-oxazolone related to α,β-unsaturated amino acids have been determined from three-dimensional X-ray data. C16H11NO2 (1a) is monoclinic, space group C2/c, Z = 8, a = 21.568(4), b = 6.757(2), c = 17.163(3) Å, β = 94.74(5)°. The investigation of 5(4H) oxazolones provides, by comparison with studies of analogous systems, information on the conformational flexibility of α, β-unsaturated amino acid derivatives. The main peculiarity is the presence of an accepting nitrogen atom instead of an NH group. This allows in principle fully planar conformations, at least to monosubstituted (both “Z” and “E”) systems.