Two cyclic dipeptide anticonvulsants: cyclo-glycyl-L-phenylglycine (1) and cyclo-L-alanyl-D-phenylglycine (2)

Abstract

In the title compounds, C 10 H 10 N 2 O 2 .0.25H 2 O (1) and C 11 H 12 N 2 O 2 (2), the phenyl rings are almost perpendicular to the mean planes of the diketopiperazine rings, which assume flattened twist-boat conformations. The methyl group of the alanyl residue in (2) lies in a quasiaxial position. In both structures, hydrogen bonds connect molecules into infinite layers. In compound (1), there are two molecules per asymmetric unit and each forms an independent layer. Water molecules bind the neighboring layers of only one type into pairs. There is no interaction between symmetrically independent molecules