(RS)-2-Oxo-4-(1-phenyl­ethyl­amino)-1,2-dihydro­quinoline-3-carb­oxy­lic acid

Svitlana V Shishkina; Igor V Ukrainets; Elena V Mospanova

doi:10.1107/S1600536811043297

. 2011 Oct 29;67(Pt 11):o3054. doi: 10.1107/S1600536811043297

(RS)-2-Oxo-4-(1-phenylethylamino)-1,2-dihydroquinoline-3-carboxylic acid

Svitlana V Shishkina ^a,^*, Igor V Ukrainets ^b, Elena V Mospanova ^b

PMCID: PMC3247446 PMID: 22220064

Abstract

The molecular structure of the title compound, C₁₈H₁₆N₂O₃, 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.

Related literature

For the S and R enantiomers, see: Ukrainets et al. (2010 ▶). For bond lengths in related structures, see: Bürgi & Dunitz (1994 ▶).

Experimental

Crystal data

C₁₈H₁₆N₂O₃
M _r = 308.33
Monoclinic,
a = 14.612 (2) Å
b = 5.9750 (6) Å
c = 18.014 (2) Å
β = 110.814 (14)°
V = 1470.0 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 293 K
0.30 × 0.10 × 0.05 mm

Data collection

Oxford Diffraction Xcalibur 3 diffractometer
10943 measured reflections
2541 independent reflections
1174 reflections with I > 2σ(I)
R _int = 0.068

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.033
S = 0.66
2541 reflections
221 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.10 e Å⁻³
Δρ_min = −0.10 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2005 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis RED (Oxford Diffraction, 2005 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811043297/jj2104sup1.cif

e-67-o3054-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811043297/jj2104Isup2.hkl

e-67-o3054-Isup2.hkl^{(124.8KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811043297/jj2104Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O1ⁱ	1.038 (17)	1.794 (17)	2.8291 (15)	174.5 (14)
N2—H2N⋯O2	0.926 (14)	1.738 (14)	2.5849 (17)	150.4 (12)
O3—H3O⋯O1	0.943 (19)	1.59 (2)	2.4712 (15)	154.1 (18)

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

In the title compound, (I), the racemate of 2-oxo-4-(1-phenylethylamino)-1,2- dihydroquinoline-3-carboxylic acid reveals high analgesic activity. Compared to its pure S and R enantiomers, they are completely inactive (Ukrainets et al., 2010). In this paper we compare the molecular and crystal structure of the racemate (I) with a previously studied structure of the pure enantiomer (II). In the title compound (Fig. 1) the formation of two strong N2—H···O2 and O3—H···O1 intramolecular hydrogen bonds (Table 1) contributes to the coplanarity of the heterocycle, carboxyl, carbonyl groups and N2 atom all to be within 0.02 Å. As a result a significant redistribution of the electron density occurs in the quinolone fragment: the O3—C10 and C8—C9 bonds are shortened (Table 1) as compared with their mean values of 1.362 Å and 1.455 Å (Bürgi & Dunitz, 1994). The O1—C9, O2—C10, and C7—C8 bonds are elongated (mean values are 1.210 Å for a Csp²= O bond and 1.418 Å for a Csp²= Csp² bond). The substituent at the amino group has a sp- conformation. The C6—C7 bond (C11/N2/C7/C6 torsion angle = -1.6 (2)%A) is twisted slghtly allowing the methyl group to be ap- oriented relative to the C7—N2 bond (C7/N2/C11/C12 torsion angle = 171.3 (1)%A). The phenyl substituent is in a -sc-conformation relative to the C7—N2 bond and is twisted toward the N2—C11 bond (C7/N2/C11/C13 and N2/C11/C13/C18 torsion angles = -67.3 (2) %A and 36.3 (2) %A, respectively). The crystal structure of (I), therefore, differs significantly from that of (II). In the pure enantiomer (II) infinite chains (Fig. 2) result from the formation of an N1—H···O2 intermolecular hydrogen bond (Ukrainets et al., 2010). In the racemte, (I), centrosymmetric dimers (Fig. 3) are formed by a N1—H1N···O1 intermolecular hydrogen bond (Table 2). This allows for Cg1—Cg1 π—π stacking interactions to be observed [centroid–centroid distance = 3.894 (1)Åⁱ; i = 1-x, 2-y, -z; Cg1 = N1/C1/C6-C9].

Experimental

2-Oxo-4-(1-phenylethylamino)-1,2-dihydroquinoline-3-carboxylic acid was synthesized using the published method (Ukrainets et al., 2010). Yield 75%. M.p. 225–227° C.