(RS)-2-Oxo-4-(1-phenyl-ethyl-amino)-1,2-dihydro-quinoline-3-carb-oxy-lic acid.

The mol-ecular structure of the title compound, C(18)H(16)N(2)O(3), does not differ in the crystals of the racemic mixture, (I), and the pure enantiomer, (II). In their crystal structures, inversion dimers occur in (I) via N-H⋯O hydrogen bonds and infinite chains in (II) also via N-H⋯O hydrogen bonds.

Methyl 2-(4-hy-droxy-1-methyl-2-oxo-1,2-dihydro-quinolin-3-yl)acetate.

In the title compound, C(13)H(13)NO(4), the bicyclic quinolone fragment and the ester group are approximately orthogonal, making a dihedral angle of 83.3 (2)° and an intramolecular C-H⋯O interaction occurs. In the crystal, inter-molecular O-H⋯O hydrogen bonding generates a zigzag chain along the c axis.