Electronic structure, novel synthesis, and O-H...O and C-H...O interactions in two 6-oxopiperidine-2-carboxylic acid derivatives.

Molecules of (S)-6-oxo-1-(thiophen-2-ylmethyl)piperidine-2-carboxylic acid, C11H13NO3S, crystallize as single enantiomers in the space group P21 and the thiophene ring is disordered over two positions, while (S)-6-oxo-1-(thiophen-3-ylmethyl)piperidine-2-carboxylic acid, C11H13NO3S, crystallizes as a single enantiomer in the space group P212121. Their absolute configurations were confirmed by anomalous dispersion effects in diffraction measurements on the crystals. The molecules of each compound are linked by a combination of strong O-H.

(11aS)-1,5,11,11a-Tetra-hydro-1-benzo-thieno[3,2-f]indolizin-3(2H)-one.

The absolute configuration of the title compound, C14H13NOS, was assigned from the synthesis and confirmed by the structure determination. There are two independent mol-ecules in the asymmetric unit. The central six-membered ring of the indolizine moiety adopts an envelope conformation, with the greatest deviations from the mean planes being 0.

(8aR,9R)-9-Hy-droxy-7,8,8a,9-tetra-hydro-furo[3,2-f]indolizin-6(4H)-one.

The title compound, C(10)H(11)NO(3), crystallizes with four independent mol-ecules in the asymmetric unit. Their geometries are very similar and corresponding bond distances are almost identical. The central six-membered ring of the indolizine moiety adopts a envelope conformation [the displacement of the flap atom (the C atom opposite the N atom) being 0.

2-Chloro-N-(2-methyl-phen-yl)benzamide.

In the title compound, C(14)H(12)ClNO, the two aromatic rings are almost coplanar, making a dihedral angle of 4.08 (18)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into infinite chains running along the a axis.

2-Chloro-N-(2,6-dimethyl-phen-yl)benzamide.

In the title compound, C(15)H(14)ClNO, the dihedral angle between the benzoyl and the aniline rings is 3.30 (18)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into chains running along the a axis.