Ethyl 1-cyclo­propyl-6,7-difluoro-8-meth­oxy-4-oxo-1,4-dihydro­quinoline-3-carboxyl­ate

De-Cai Wang; Xin-Ming Huang; Yan-Ping Liu; Chun-Lei Tang

doi:10.1107/S1600536808034715

. 2008 Oct 31;64(Pt 11):o2214. doi: 10.1107/S1600536808034715

Ethyl 1-cyclopropyl-6,7-difluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylate

De-Cai Wang ^a,^*, Xin-Ming Huang ^a, Yan-Ping Liu ^a, Chun-Lei Tang ^a

PMCID: PMC2959496 PMID: 21581071

Abstract

In the title compound, C₁₆H₁₅F₂NO₄, the dihedral angle between the three-membered ring and the quinoline ring system is 64.3 (3)°. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules, forming a column running along [101].

Related literature

The title compound is a key intermediate in the synthesis of a series of fluoroquinolones, see: Matsumoto et al. (1996 ▶); Nagano et al. (1989 ▶); Petersen et al. (1993 ▶).

Experimental

Crystal data

C₁₆H₁₅F₂NO₄
M _r = 323.29
Monoclinic,
a = 16.395 (3) Å
b = 17.732 (4) Å
c = 12.199 (2) Å
β = 123.71 (3)°
V = 2950.1 (14) Å³
Z = 8
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 293 (2) K
0.10 × 0.10 × 0.05 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.988, T _max = 0.994
2760 measured reflections
2663 independent reflections
1580 reflections with I > 2σ(I)
R _int = 0.068
3 standard reflections every 200 reflections intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.061
wR(F ²) = 0.175
S = 1.04
2663 reflections
208 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808034715/is2351sup1.cif

e-64-o2214-sup1.cif^{(19.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808034715/is2351Isup2.hkl

e-64-o2214-Isup2.hkl^{(130.9KB, hkl)}

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
C1—H1A⋯O2ⁱ	0.96	2.58	3.220 (8)	124
C12—H12B⋯O2ⁱⁱ	0.97	2.50	3.273 (5)	136

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Symmetry codes: (i) Inline graphic ; (ii) .

supplementary crystallographic information

Comment

The title compound, 1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid ethyl ester, is a key intermediate to synthesize a series of fluoroquinolones,such as moxifloxacin (Petersen et al., 1993), balofloxacin (Nagano et al., 1989) and gatifloxacin (Matsumoto et al., 1996). As part of our studies in this area, we report here the synthesis and crystal structure of the title compound, (I) (Fig. 1).

The benzene ring and its adjacent six-membered ring were almost coplanar. The dihedral angles between the three-membered ring and the benzene ring is 65.30 (14)°. In the crystal structure, intermolecular C—H···O hydrogen bonds link the molecules, in which they are effective in the stabilization of the structure.

Experimental

A solution of 26 g (0.075 mol) of 3-cyclopropylamino-2- (2,4,5-trifluoro-3-methoxybenzoyl)acrylic acid ethyl ester and 110 ml of DMF was treated with 22 g (0.16 mol) of K₂CO₃, and then heated to 50 °C with stirring for 1 h. The resulting precipitate was filtered, washed with the mixture of ice and water, and dried to give 23 g of the title compound (yield 95%). Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of a methanol solution.