5,6,7,8-Tetra­hydro­quinolin-8-one

In the quinoline fused-ring system of the title compound, C₉H₉NO, the pyridine ring is planar to within 0.011 (3) Å, while the partially saturated cyclo­hexene ring adopts a sofa conformation with an asymmetry parameter ΔC_s(C6) = 1.5 (4)°. There are no classical hydrogen bonds in the crystal structure. Mol­ecules form mol­ecular layers parallel to (100) with a distance between the layers of a/2 = 3.468 Å.

Related literature

The title compound is an inter­mediate for the synthesis of polyheterocycles giving photoluminescence (Kelly & Lebedev, 2002) and a key substrate to synthesis of its 8-amino substituted derivatives with pharmacological activity (e.g. Gudmundsson et al., 2009). For our ongoing study on the synthesis and structure of condensed pyridine and quinoline derivatives, see: Lipińska (2005); Karczmarzyk et al. (2010). For the synthesis, see: Kelly & Lebedev (2002). For a related structure, see: OXHYQU (Cygler et al., 1981). For structure inter­pretation tools, see: Bruno et al. (2002); Spek (2009). For a description of the Cambridge Structural Database, see: Allen (2002). For bond-length data, see: Allen et al. (1987). For asymmetry parameters, see: Duax & Norton (1975).

Experimental

Crystal data

• C₉H₉NO

• M_r = 147.17

• Orthorhombic, P 2₁ 2₁ 2₁

• a = 6.9393 (2) Å

• b = 8.0885 (3) Å

• c = 13.4710 (4) Å

• V = 756.11 (4) ų

• Z = 4

• Cu Kα radiation

• μ = 0.68 mm⁻¹

• T = 293 K

• 0.60 × 0.16 × 0.15 mm

Data collection

• Bruker SMART APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005) T_min = 0.878, T_max = 1.000

• 5358 measured reflections

• 761 independent reflections

• 734 reflections with I > 2σ(I)

• R_int = 0.022

Refinement

• R[F² > 2σ(F²)] = 0.050

• wR(F²) = 0.153

• S = 1.14

• 761 reflections

• 100 parameters

• H-atom parameters constrained

• Δρ_max = 0.28 e Å⁻³

• Δρ_min = −0.18 e Å⁻³

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; 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: SHELXL97 and WinGX (Farrugia, 1999).

Supporting information

S1. Comment

6,7-Didro-5H-quinolin-8-one, (I), is an important intermediate for the synthesis of polyheterocycles giving photoluminescence (Kelly & Lebedev, 2002) and a key substrate to synthesis of its 8-amino substituted derivatives with pharmacological activity (e.g. Gudmundsson et al., 2009). As a part of our ongoing study on the synthesis and structure of condensed pyridine and quinoline derivatives (Lipińska, 2005; Karczmarzyk et al., 2010) we report herein the X-ray structure of the title compound. This compound is well-known on organic chemistry but its crystal structure is not current in the Cambridge Structural Database (November 2010 Release; Allen, 2002; Bruno et al., 2002).

The bond lengths and angles for (I) are within expected ranges (Allen et al., 1987) and are comparable to the corresponding values observed in related structure of 8-oxo-2-phenyl-5,6,7,8-tetrahydroquinoline (OXHYQU; CSD, November 2010 Release). In the two-ring fused system the aromatic pyridine ring is planar within 0.011 (3) Å, while the partially saturated cyclohexene ring adopts a sofa conformation with asymmetry parameter ΔC_S(C6) = 1.5 (4)° (Duax & Norton, 1975).

There are no classical hydrogen bonds in the crystal structure of (I). The nearly planar molecules form molecular layers parallel to (100) crystallographic plane (Fig. 2) imposing in the unit cell the pseudo-mirror plane passing through N, O, C(sp²) and C5(sp³) atoms (higher pseudosymmetry Pnma space group). The distance between neighbouring planes of a/2 = 3.468 Å is comparable to a van der Waals distance of about 3.5 Å for the π-π interacting aromatic skeletons of pyridine rings.

Related literature

The title compound is an intermediate for the synthesis of polyheterocycles giving photoluminescence (Kelly & Lebedev, 2002) and a key substrate to synthesis of its 8-amino substituted derivatives with pharmacological activity (e.g. Gudmundsson et al., 2009). For our ongoing study on the synthesis and structure of condensed pyridine and quinoline derivatives, see: Lipińska (2005); Karczmarzyk et al. (2010). For the synthesis, see: Kelly & Lebedev (2002). For a related structure, see: OXHYQU (Please give author names). For structure interpretation tools, see: Bruno et al. (2002); Spek (2009). For a description of the Cambridge Structural Database, see: Allen (2002). For bond-length data, see:Allen et al. (1987). For asymmetry parameters, see: Duax & Norton (1975).

S2. Experimental

The titled compound was obtained by ozonolysis of 8-benzylidene-5,6,7,8-tetrahydroquinoline according to the method described by Kelly & Lebedev (2002). Crystals suitable for X-ray diffraction analysis were grown by slow evaporation of a ethyl acetate/hexane (1:1) solution.

S3. Refinement

The H atoms were positioned geometrically and treated as riding on their C atoms, with C—H distances of 0.93 (aromatic) and 0.97 Å (CH₂), and were refined with U_ĩso(H) values of 1.5U_eq(C). The Flack parameter originally was refined to 0.4 (6), which is essentially indeterminate. For this reason, the Friedel equivalents were merged using MERG4 in SHELXL97 (Sheldrick, 2008) and the absolute structure was arbitrarily assigned. The PLATON symmetry check (Spek, 2009) reveals the presence of pseudosymmetry in the structure suggesting the higher symmetry space group Pnma in the unit cell with the cell constants of a' = b, b' = a and c' = c and origin shifted to:-0.2500, 0.2577, 0.0000. This pseudosymmetry forces the molecule to locate on the crystallographic mirror plane passing through N, O, all C(sp²) and C5(sp³) atoms and C6 atom to be disordered over two positions above and below the mirror plane. The attempt to refine the structure in the Pnma space group resulted in a more disordered model with high R and wR values of 0.199 and 0.527, respectively.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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: SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of (I), with atom labels and 30% probability displacement ellipsoids for non-H atoms.
	Fig. 2. A view of the molecular packing in (I).

5,6,7,8-Tetrahydroquinolin-8-one

Crystal data

C9H9NO	Dx = 1.293 Mg m^−3
Mr = 147.17	Melting point = 369–371 K
Orthorhombic, P212121	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: P 2ac 2ab	Cell parameters from 40 reflections
a = 6.9393 (2) Å	θ = 7.2–34.8°
b = 8.0885 (3) Å	µ = 0.68 mm^−1
c = 13.4710 (4) Å	T = 293 K
V = 756.11 (4) Å^3	Needle, colourless
Z = 4	0.60 × 0.16 × 0.15 mm
F(000) = 312

Data collection

Bruker SMART APEXII CCD diffractometer	761 independent reflections
Radiation source: fine-focus sealed tube	734 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 65.0°, θmin = 6.4°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −8→8
Tmin = 0.878, Tmax = 1.000	k = −9→7
5358 measured reflections	l = −15→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.153	H-atom parameters constrained
S = 1.14	w = 1/[σ^2(Fo^2) + (0.1138P)^2 + 0.0433P] where P = (Fo^2 + 2Fc^2)/3
761 reflections	(Δ/σ)max < 0.001
100 parameters	Δρmax = 0.28 e Å^−3
0 restraints	Δρmin = −0.18 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.0077 (5)	0.3562 (2)	0.54598 (13)	0.0827 (8)
N1	0.0144 (4)	0.0574 (3)	0.64019 (14)	0.0617 (6)
C2	0.0232 (4)	−0.0911 (4)	0.68161 (18)	0.0673 (7)
H2	0.0116	−0.0986	0.7502	0.101*
C3	0.0486 (5)	−0.2350 (4)	0.6282 (2)	0.0763 (9)
H3	0.0575	−0.3364	0.6604	0.114*
C4	0.0606 (6)	−0.2257 (3)	0.5270 (2)	0.0784 (10)
H4	0.0776	−0.3212	0.4896	0.118*
C5	0.0569 (7)	−0.0575 (4)	0.36824 (19)	0.0850 (12)
H51	0.1908	−0.0533	0.3478	0.128*
H52	−0.0010	−0.1544	0.3381	0.128*
C6	−0.0431 (6)	0.0917 (4)	0.3321 (2)	0.0899 (11)
H61	−0.1807	0.0782	0.3419	0.135*
H62	−0.0203	0.1031	0.2613	0.135*
C7	0.0218 (5)	0.2459 (3)	0.38350 (19)	0.0685 (8)
H71	−0.0596	0.3370	0.3626	0.103*
H72	0.1526	0.2708	0.3630	0.103*
C8	0.0157 (4)	0.2338 (3)	0.49507 (19)	0.0547 (6)
C9	0.0250 (3)	0.0646 (3)	0.54022 (17)	0.0498 (6)
C10	0.0472 (4)	−0.0740 (3)	0.48064 (18)	0.0593 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.1330 (18)	0.0423 (10)	0.0727 (12)	−0.0004 (12)	0.0010 (14)	−0.0078 (7)
N1	0.0823 (14)	0.0571 (12)	0.0455 (10)	0.0067 (12)	0.0018 (10)	−0.0021 (8)
C2	0.0834 (17)	0.0693 (15)	0.0491 (12)	0.0051 (16)	0.0046 (12)	0.0103 (11)
C3	0.099 (2)	0.0553 (16)	0.0748 (16)	0.0030 (15)	0.0054 (16)	0.0198 (12)
C4	0.121 (3)	0.0434 (15)	0.0710 (17)	0.0049 (16)	0.0102 (17)	−0.0019 (11)
C5	0.146 (3)	0.0603 (17)	0.0493 (14)	−0.0020 (19)	0.0052 (16)	−0.0100 (11)
C6	0.141 (3)	0.080 (2)	0.0489 (13)	−0.011 (2)	−0.0132 (16)	0.0019 (13)
C7	0.0942 (18)	0.0564 (14)	0.0549 (13)	−0.0025 (14)	−0.0030 (14)	0.0134 (11)
C8	0.0668 (13)	0.0410 (12)	0.0563 (12)	−0.0016 (11)	0.0007 (12)	−0.0020 (9)
C9	0.0616 (12)	0.0445 (12)	0.0434 (10)	−0.0013 (11)	0.0012 (10)	−0.0015 (8)
C10	0.0805 (16)	0.0462 (13)	0.0512 (13)	−0.0051 (13)	0.0066 (11)	−0.0042 (10)

Geometric parameters (Å, º)

O1—C8	1.205 (3)	C5—H51	0.9700
N1—C2	1.326 (3)	C5—H52	0.9700
N1—C9	1.350 (3)	C6—C7	1.497 (4)
C2—C3	1.380 (4)	C6—H61	0.9700
C2—H2	0.9300	C6—H62	0.9700
C3—C4	1.368 (4)	C7—C8	1.507 (3)
C3—H3	0.9300	C7—H71	0.9700
C4—C10	1.380 (4)	C7—H72	0.9700
C4—H4	0.9300	C8—C9	1.499 (3)
C5—C6	1.475 (5)	C9—C10	1.387 (3)
C5—C10	1.521 (3)
C2—N1—C9	117.2 (2)	C5—C6—H62	109.0
N1—C2—C3	123.4 (2)	C7—C6—H62	109.0
N1—C2—H2	118.3	H61—C6—H62	107.8
C3—C2—H2	118.3	C6—C7—C8	113.5 (2)
C4—C3—C2	118.7 (2)	C6—C7—H71	108.9
C4—C3—H3	120.6	C8—C7—H71	108.9
C2—C3—H3	120.6	C6—C7—H72	108.9
C3—C4—C10	119.7 (2)	C8—C7—H72	108.9
C3—C4—H4	120.1	H71—C7—H72	107.7
C10—C4—H4	120.1	O1—C8—C9	121.4 (2)
C6—C5—C10	112.3 (3)	O1—C8—C7	121.0 (2)
C6—C5—H51	109.1	C9—C8—C7	117.57 (19)
C10—C5—H51	109.1	N1—C9—C10	123.3 (2)
C6—C5—H52	109.1	N1—C9—C8	116.21 (19)
C10—C5—H52	109.1	C10—C9—C8	120.5 (2)
H51—C5—H52	107.9	C4—C10—C9	117.7 (2)
C5—C6—C7	112.8 (3)	C4—C10—C5	121.7 (2)
C5—C6—H61	109.0	C9—C10—C5	120.7 (2)
C7—C6—H61	109.0
C9—N1—C2—C3	2.2 (4)	O1—C8—C9—C10	−175.6 (3)
N1—C2—C3—C4	−1.8 (5)	C7—C8—C9—C10	2.9 (4)
C2—C3—C4—C10	0.1 (6)	C3—C4—C10—C9	1.0 (5)
C10—C5—C6—C7	52.3 (4)	C3—C4—C10—C5	−179.1 (4)
C5—C6—C7—C8	−51.6 (4)	N1—C9—C10—C4	−0.5 (4)
C6—C7—C8—O1	−158.0 (3)	C8—C9—C10—C4	178.1 (3)
C6—C7—C8—C9	23.5 (4)	N1—C9—C10—C5	179.6 (3)
C2—N1—C9—C10	−1.0 (4)	C8—C9—C10—C5	−1.8 (4)
C2—N1—C9—C8	−179.7 (2)	C6—C5—C10—C4	154.3 (3)
O1—C8—C9—N1	3.1 (4)	C6—C5—C10—C9	−25.9 (5)
C7—C8—C9—N1	−178.4 (3)