Dimethyl 8-acetyl-2-methyl-1,2-dihydro­quinoline-2,4-dicarboxyl­ate

Zeynep Keleşoğlu; Zeynep Gültekin; Orhan Büyükgüngör

doi:10.1107/S1600536811003564

. 2011 Feb 2;67(Pt 3):o544–o545. doi: 10.1107/S1600536811003564

Dimethyl 8-acetyl-2-methyl-1,2-dihydroquinoline-2,4-dicarboxylate

Zeynep Keleşoğlu ^a, Zeynep Gültekin ^b, Orhan Büyükgüngör ^a,^*

PMCID: PMC3052105 PMID: 21522312

Abstract

In the title compound, C₁₆H₁₇NO₅, the six-membered N-containing ring has a half-boat form; the spiro C atom deviates by 0.34 (2) Å from the plane (r.m.s. deviation = 0.051 Å) defined by the N and four aromatic C atoms. Intramolecular N—H⋯O hydrogen bonding generates an S(6) ring motif and the dihedral angle between the mean plane though the S(6) ring and that through the five-atom half-boat plane is 3.39 (2)°. In the crystal, weak intermolecular C—H⋯O hydrogen bonds link molecules into zigzag chains along [001] due to c-glide symmetry, and C—H⋯π interactions extend along [010].

Related literature

For the preparation of 1,2-dihydroquinoline, see: Dauphinee & Forrest (1978 ▶); Katritzky et al. (1996 ▶); Elmore et al. (2001 ▶); Lu & Malinakova (2004 ▶); Wang et al. (2009 ▶); Rezgui et al. (1999 ▶). For related structures, see: Yadav et al. (2007 ▶); Kamakshi & Reddy (2007 ▶); Kim et al. (2001 ▶); Sundèn et al. (2007 ▶); Waldmann et al. (2008 ▶). For ring puckering analysis, see: Cremer & Pople (1975 ▶). For graph-set theory, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₆H₁₇NO₅
M _r = 303.31
Monoclinic,
a = 8.0222 (3) Å
b = 18.2466 (9) Å
c = 10.3478 (4) Å
β = 101.042 (3)°
V = 1486.65 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 296 K
0.74 × 0.43 × 0.23 mm

Data collection

Stoe IPDS 2 diffractometer
Absorption correction: integration (X-RED32; Stoe & Cie, 2002 ▶) T _min = 0.823, T _max = 0.968
14613 measured reflections
3068 independent reflections
2221 reflections with I > 2σ(I)
R _int = 0.055

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.169
S = 1.07
14613 reflections
205 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2002 ▶); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811003564/si2329sup1.cif

e-67-0o544-sup1.cif^{(18.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811003564/si2329Isup2.hkl

e-67-0o544-Isup2.hkl^{(147.5KB, hkl)}

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

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

Cg1 is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1	0.86 (2)	1.95 (2)	2.650 (2)	138 (2)
C10—H10⋯O3ⁱ	0.93	2.59	3.517 (3)	174
C14—H14C⋯Cg1ⁱ	0.96	2.89	3.692 (3)	142
C8—H8B⋯Cg1ⁱⁱ	0.96	2.85	3.501 (3)	126

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

Acknowledgments

The title product was synthesized at RWTH Aachen University. The authors thank Professor Magnus Rueping of RWTH Aachen University, Germany, for helpful discussions and acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund).

supplementary crystallographic information

Comment

Dihydroquinoline moiety is found in a wide variety of natural products and they have attracted a lot of attention from synthetic organic chemists (Kamakshi & Reddy, 2007). 1,2-Dihydroquinolines have received substantial attention due to their potential biological activities arising from their antioxidative properties as well as their usefulness as precursors of some other biologically active compounds (Kim et al., 2001). 1,2-Dihydroquinoline derivatives are known to exhibit a wide spectrum of biological activities such as antimalarial, antibacterial and anti-inflammatory behavior (Yadav et al., 2007).

Asymmetric synthesis of 1,2-dihydroquinolin have been attracted in recent years (Wang et al., 2009; Rezgui et al., 1999). Sundèn and co-worker has reported asymmetric synthesis of 1,2-dihydroquinolines using Domino reactions between 2-aminobenzaldehyde and α,β-unsaturated aldehydes to give pharmaceutically valuable 1,2-dihydroquinolines in high enantioselectivity (Sundèn et al., 2007). 1,2-dihydroquinolines was used for several applications, such as synthesis of quinolines: (Dauphinee & Forrest, 1978; Lu & Malinakova, 2004), 1,2,3,4- tetrahydroquinolines: (Katritzky et al., 1996) and natural products: (Elmore et al., 2001).

The molecule of the title compound contains dihydroquinoline, two methoxycarbonyl (O=C—O—CH₃) and acetyl group (O=C—CH₃). The two –CO₂Me groups are antisymmetric with respect to atom C10 (Fig. 1).

The six-membered N containing ring of the quinoline system displays a half-boat conformation with the puckering parameters of Q_T=0.261 (2) Å, Φ=146.7 (6)° and Θ=112.7 (4) ° (Cremer & Pople, 1975) and the spiro carbon atom deviates 0.34 (2) Å from the plane (r.m.s. deviation 0.051 Å) defined by the N1 and C1, C6, C9, C10 atoms. The intramolecular N—H..O hydrogen bond generate S(6) ring motif (Bernstein et al., 1995) (Fig. 1, Table 1). The dihedral angle between the S(6) ring mean plane and the half-boat plane of five atoms is 3.39 (2)°.

The crystal packing is stabilized by C10—H10···O3ⁱ intermolecular hydrogen bonds linking the molecules into chains in a zigzag mode along [0 0 1] due to c-glide symmetry, and there are also two C—H···π interactions C14—H14c···Cg1ⁱ and C8—H8b···Cg1ⁱⁱ [(i): x,1/2 - y,-1/2 + z; (ii):1 - x,1 - y,1 - z] extending along the b axis (Fig. 2., Table 1.).

Experimental

The title compound was synthesized after a method described by Waldmann et al., (2008). 2'-aminoacetophenone (100 mg, 1 eq) was dissolved in acetonitrile (1.5 ml) in a screw-capped test tube and Bi(OTf)₃ (5 mol %, 0.05 eq) was added to the mixture. This mixture were stirred at room temperature for 4 days until the starting material was completely consumed as monitored by TLC. The resultant residue was directly purified by flash chromatography on silica (EtOAc: Cyclohexane 2:98) gave 27% yield as a yellow solid. Recrystallized over pentan and ethyl acetate gave yellow crystalline solid. R_f 0.5 (2:1 Cyclohexane/EtOAc); m.p: (374–375 K).