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.

(5S,11aS)-5-Hydro-per-oxy-1,5,11,11a-tetra-hydro-[1]benzothieno[3,2-f]indol-izin-3(2H)-one.

The absolute configuration of the title compound, C14H13NO3S, was assigned from the synthesis and confirmed by the structure determination. The central six-membered ring of the indolizine moiety adopts an envelope conformation, with the greatest deviation from the mean plane of the ring being 0.661 (2) Å for the bridgehead C atom.

(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.

4-Chloro-N-(3,5-dimethyl-phen-yl)benzamide.

In the mol-ecular structure of the title compound, C(15)H(14)ClNO, the amide group forms dihedral angles of 15.8 (2) and 27.2 (2)°, respectively, with the benzoyl and aniline rings, while the angle between the benzoyl and aniline rings is 11.

2-Chloro-N-(3-methyl-phen-yl)benzamide.

In the structure of the title compound, C(14)H(12)ClNO, the ortho-Cl atom in the benzoyl ring is positioned syn to the C=O bond, while the meta-methyl group in the aniline ring is positioned anti to the N-H bond. The amide group forms dihedral angles of 60.1 (1) and 22.

(6S,7S,8S,8aS)-6-Ethyl-3-oxo-1,2,3,5,6,7,8,8a-octa-hydro-indolizine-7,8-diyl diacetate.

In the mol-ecular structure of the title compound, C(14)H(21)NO(5), the six-membered ring of the indolizine moiety adopts a chair conformation. There are two independent mol-ecules in the asymmetric unit. The oxopyrrolidine ring attached to the indolizine ring system is nearly planar, with mean deviations of 0.

N-(4-Chloro-phen-yl)-4-methyl-benzamide.

In the title compound, C(14)H(12)ClNO, the aromatic rings make a dihedral angle of 59.25 (5)°. The methyl group is disordered over two equally occupied positions.

3-Methyl-N-(4-methyl-phen-yl)benzamide.

In the title compound, C(15)H(15)NO, the two aromatic rings make a dihedral angle of 70.06 (3)°, while the central amide core -NH-C(=O)- is twisted by 30.24 (4) and 40.

(4R,6S,7S,8S,8aS)-6-Ethyl-7,8-dihy-droxy-4-methyl-1,2,3,5,6,7,8,8a-octa-hydro-indolizin-4-ium iodide.

The title compound, C(11)H(22)NO(2) (+)·I(-), is a chiral mol-ecule with five stereogenic centres. The absolute configuration was assigned from the synthesis and confirmed by the structure determination. The central six-membered ring of the indolizine system adopts a chair conformation, with two atoms displaced by -0.

N-(2,3-Dimethyl-phen-yl)-2-methyl-benzamide.

In the title compound, C(16)H(17)NO, the two aromatic rings make a dihedral angle of 5.9 (2)°, while the central amide core -NH-C(=O)- is twisted by 44.0 (3) and 47.

N-(4-Chloro-2-methyl-phen-yl)maleamic acid.

In the mol-ecular structure of the title compound, C(11)H(10)ClNO(3), the conformation of the N-H bond in the amide segment is syn to the ortho-methyl group in the phenyl ring. The C=O and O-H bonds of the acid group are in the relatively rare anti position with respect to each other. This is an obvious consequence of the hydrogen bond donated to the amide carbonyl group.

(8aRS)-8,8a-Dihydro-furo[3,2-f]indolizine-6,9(4H,7H)-dione.

The title compound, C(10)H(9)NO(3), is a chiral mol-ecule with one stereogenic carbon atom, but which crystallizes as a racemate in the centrosymmetric space group P2(1)/n. The central six-membered ring of the indolizine moiety adopts a definite envelope conformation, while the conformation of the oxopyrrolidine ring is close to that of a flat-envelope with a maximum deviation of 0.352 (1) Å for the flap atom.

(6S,7S,8S,8aS)-6-Ethyl-7,8-dihy-droxy-1,5,6,7,8,8a-hexa-hydro-indolizin-3(2H)-one monohydrate.

The absolute configuration of the title compound, C(10)H(17)NO(3)·H(2)O, was assigned from the synthesis. In the mol-ecular structure, the central six-membered ring of the indolizine moiety adopts a chair conformation, with two atoms displaced by -0.578 (2) and 0.

(6S,7S,8R,8aS)-6-Ethyl-perhydro-indolizine-7,8-diol.

In the title compound, C(10)H(19)NO(2), the piperidine and pyrrolidine rings of the perhydro-indolizine ring system adopt chair and envelope conformations, respectively. In the crystal structure, inter-molecular O-H⋯N and O-H⋯O hydrogen bonds link the mol-ecules into a chain running along the a axis.

(3aR,8aS,9S,9aR)-9-Hydroxy-perhydro-furo[3,2-f]indolizin-6-one.

In the title compound, C(10)H(15)NO(3), the central six-membered ring of the indolizine system adopts a chair conformation, while the oxopyrrolidine and hydro-furan rings attached to the indolizine ring system have envelope conformations. In the crystal, the mol-ecules form chains parallel to the b axis via inter-molecular O-H⋯O hydrogen bonds. The absolute configuration was assigned from the synthesis.

(7R,8S,8aS)-8-Hydr-oxy-7-phenyl-perhydro-indolizin-3-one.

In the title compound, C(14)H(17)NO(2), the six-membered ring of the indolizine system adopts a chair conformation. In the crystal, mol-ecules form chains parallel to the b axis via inter-molecular O-H⋯O hydrogen bonds. The absolute mol-ecular configuration was assigned from the synthesis.

(7R,8R,8aS)-8-Hydr-oxy-7-phenyl-per-hydro-indolizin-3-one.

The absolute configuration of the title compound, C(14)H(17)NO(2), was assigned from the synthesis. There are two mol-ecules in the asymmetric unit. Their geometries are very similar and corresponding bond lengths are almost identical [mean deviation for all non-H atoms = 0.

(8aS)-7,8,8a,9-Tetra-hydro-thieno[3,2-f]indolizin-6(4H)-one.

In the mol-ecular structure of the title compound, C(10)H(11)NOS, the central six-membered ring of the indolizine unit adopts an envelope conformation, the maximum deviations from the mean plane of the ring being 0.533 (2) Å. The fused thieno ring is nearly coplanar [mean deviation = 0.

(11R,11aS)-11-Hydr-oxy-1,5,11,11a-tetra-hydro-1-benzothieno[2,3-f]indolizin-3(2H)-one.

The absolute configuration of the title compound, C(14)H(13)NO(2)S, was assigned from the synthesis and confirmed by the structure determination. The central six-membered ring of the indolizine system adopts an envelope conformation, the greatest deviation from the mean plane of the ring being 0.459 (2) Å for the N atom.