2-(Cyclo­hexyl­amino)-1,4-naphthoquinone

Knight, J.C.; Tatchell, T.; Fallis, I.A.

doi:10.1107/S1600536807005466

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 63| Part 3| March 2007| Pages o1226-o1227

https://doi.org/10.1107/S1600536807005466

2-(Cyclohexylamino)-1,4-naphthoquinone

James C. Knight,^a ^* Thomas Tatchell ^a and Ian A. Fallis ^a

^aMain Building, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales
^*Correspondence e-mail: knightjc@cardiff.ac.uk

(Received 31 January 2007; accepted 1 February 2007; online 9 February 2007)

The molecules of the title compound, C₁₆H₁₇NO₂, interact by π–π stacking between the naphthoquinone ring systems.

Comment

In research focusing on the development of redox-active naphthoquinone-based chealting agents we have observed unexpected reactivity of amine-substituted chloronapthoquinones and we report here a by-product from one of our syntheses. In an attempt to prepare 3-(cyclohexylamino)-2-(p-tolylsulfanyl)naphthalene-1,4-dione by reaction of 2-chloro-3-(cyclohexylamino)naphthalene-1,4-dione with thiocresol under basic conditions, we isolated the title compound, (I), in modest yield. We postulate that the dechlorinated product was obtained via a quinolic intermediate obtained after oxidation of thiocresol to the corresponding disulfide. The reduction of chloronaphthoquinones has been described before (Reynolds et al., 1964 ), but what is unusual here is that a low-potential aminoquinone is acting as an oxidant. Elimination of HCl from the intermediate 2-chloro-3-(cyclohexylamino)naphthalene-1,4-diol would be readily achieved under the basic conditions employed to afford the title compound.

In (I), the naphthoquinone system is substituted with a cyclohexylamino group in position 2 (Fig. 1). The cyclohexyl group is in the chair conformation with an average C—C bond length of 1.496 (2) Å which lies well within the range of classical values. The central C10—N1—C11 angle is 126.73 (12)°, a value which is slightly more obtuse than that found in the related compound 3-chloro-2-pyrrolidino-1,4-naphthoquinone (Lynch et al., 2002 ). An acute intramolecular N—H⋯O bond (Table 1) helps to establish the molecular conformation of (I).

The molecular packing diagram (Fig. 2) shows the occurrance of centrosymmetric intermolecular π–π stacking of the C1/C2/C3/C8/C9/C10 aromatic ring, with a centroid–centroid distance of 3.8694 (8) Å.

Figure 1
View of the molecular structure of (I)

, showing 50% displacement ellipsoids (H atoms are represented by spheres of arbitrary radius).

Figure 2
The packing of (I)

showing the π–π stacking. The dashed line indicates the intramolecular hydrogen bond.

Experimental

3-Chloro-2-(cyclohexylamino)-1,4-naphthoquinone (0.5 g, 1.73 mmol), potassium carbonate (365 mg, 2.64 mmol) and p-thiotoluene (241 mg, 2.54 mmol) were reacted in acetonitrile (40 ml). The solution mixture was refluxed overnight under an inert nitrogen atmosphere. This solution was filtered, dried and purified by flash column chromatography (SiO₂) using CHCl₃ as the eluant. The title compound was found at R_F = 0.36. Ruby-red blocks of (I) were obtained by slow evaporation of a CHCl₃ solution (yield 185 mg, 42%).

Crystal data

C₁₆H₁₇NO₂
M_r = 255.31
Monoclinic, P 2₁ /c
a = 10.3204 (3) Å
b = 6.3380 (2) Å
c = 18.9664 (7) Å
β = 96.179 (1)°
V = 1233.40 (7) Å³
Z = 4
D_x = 1.375 Mg m⁻³
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 (2) K
Block, red
0.52 × 0.40 × 0.22 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
φ and ω scans
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ) T_min = 0.954, T_max = 0.980
11095 measured reflections
3094 independent reflections
2075 reflections with I > 2σ(I)
R_int = 0.068
θ_max = 28.7°

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.136
S = 1.05
3094 reflections
172 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0722P)² + 0.0683P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O2	0.88	2.19	2.5917 (16)	107

The H atoms were placed in calculated positions (C—H = 0.95–1.00 and N—H = 0.88 Å) and refined as riding, with U_iso(H) = 1.2Ueq(C,N).

Data collection: COLLECT (Nonius, 2000 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536807005466/hb2282sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807005466/hb2282Isup2.hkl

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).

2-(Cyclohexylamino)-1,4-naphthoquinone top

Crystal data top

C₁₆H₁₇NO₂	F(000) = 544
M_r = 255.31	D_x = 1.375 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6520 reflections
a = 10.3204 (3) Å	θ = 2.9–27.5°
b = 6.3380 (2) Å	µ = 0.09 mm⁻¹
c = 18.9664 (7) Å	T = 150 K
β = 96.179 (1)°	Block, red
V = 1233.40 (7) Å³	0.52 × 0.40 × 0.22 mm
Z = 4

Data collection top

Bruker–Nonius KappaCCD diffractometer	3094 independent reflections
Radiation source: fine-focus sealed tube	2075 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.068
φ and ω scans	θ_max = 28.7°, θ_min = 3.1°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −13→12
T_min = 0.954, T_max = 0.980	k = −8→8
11095 measured reflections	l = −23→24

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.136	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0722P)² + 0.0683P] where P = (F_o² + 2F_c²)/3
2944 reflections	(Δ/σ)_max = 0.001
172 parameters	Δρ_max = 0.21 e Å⁻³
0 restraints	Δρ_min = −0.28 e Å⁻³

Special details top

Experimental. ¹H NMR (CDCl₃): δ 1.10–1.35 (m, 5H, Cy ring), 1.55 (m, 1H, Cy ring), 1.70 (m, 2H, Cy ring), 1.95 [dd, (J_HH = 1.70 + 3.40 Hz), 2H, Cy ring], 3.20 [quintet, (J_HH = 3.20 Hz), 1H, Cy ring], 5.65 (s, 1H, Ar), 5.75 [d, (J_HH = 5.77 Hz), 1H, NH], 7.45 [t, (J_HH = 7.50 Hz), 1H, Ar], 7.60 [t, (J_HH = 7.60 Hz), 1H, Ar], 7.90 [d, (J_HH = 7.90 Hz), 1H, Ar] and 7.95 [d, (J_HH = 8.00 Hz), 1H, Ar]. ¹³C NMR (CDCl₃): δ 24.56, 25.46, 31.64, 31.86, 51.12, 100.73, 126.07, 126.21, 130.56, 131.56, 133.66, 134.67, 146.67, 182.09, 182.82. IR (KBr) cm^-1: 3342, 3041, 2926, 2856, 1671, 1619, 1597, 1571, 1522, 1441, 1350, 1304, 1267, 1250, 1120, 1098, 1002, 952, 890, 862, 778, 726, 669, 635 and 565.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.62825 (14)	0.2358 (2)	1.01432 (8)	0.0225 (3)
H1A	0.6059	0.1130	0.9870	0.027*
C2	0.54304 (13)	0.3009 (2)	1.06508 (8)	0.0218 (3)
C3	0.57619 (13)	0.4910 (2)	1.10630 (7)	0.0188 (3)
C4	0.49385 (14)	0.5627 (2)	1.15364 (8)	0.0243 (4)
H4	0.4178	0.4850	1.1610	0.029*
C5	0.52166 (15)	0.7429 (2)	1.18922 (8)	0.0272 (4)
H5	0.4660	0.7931	1.2223	0.033*
C6	0.63093 (15)	0.8536 (3)	1.17734 (8)	0.0279 (4)
H6	0.6487	0.9837	1.2014	0.033*
C7	0.71608 (14)	0.7814 (2)	1.13138 (8)	0.0233 (3)
H7	0.7925	0.8591	1.1246	0.028*
C8	0.68908 (13)	0.5990 (2)	1.09624 (7)	0.0189 (3)
C9	0.78112 (13)	0.5186 (2)	1.04880 (8)	0.0189 (3)
C10	0.73880 (13)	0.3397 (2)	1.00320 (7)	0.0192 (3)
C11	0.80372 (14)	0.1429 (2)	0.89982 (8)	0.0205 (3)
H11	0.7102	0.0986	0.8930	0.025*
C12	0.88468 (16)	−0.0420 (2)	0.92266 (9)	0.0280 (4)
H12A	0.8546	−0.1035	0.9660	0.034*
H12B	0.9767	0.0019	0.9338	0.034*
C13	0.87457 (16)	−0.2031 (2)	0.86481 (9)	0.0318 (4)
H13A	0.7837	−0.2553	0.8573	0.038*
H13B	0.9314	−0.3242	0.8799	0.038*
C14	0.91285 (15)	−0.1184 (3)	0.79535 (9)	0.0290 (4)
H14A	1.0056	−0.0755	0.8014	0.035*
H14B	0.9021	−0.2302	0.7587	0.035*
C15	0.83056 (15)	0.0644 (2)	0.77231 (8)	0.0264 (4)
H15A	0.7386	0.0192	0.7621	0.032*
H15B	0.8592	0.1251	0.7284	0.032*
C16	0.84189 (14)	0.2266 (2)	0.82992 (8)	0.0219 (3)
H16A	0.7854	0.3481	0.8148	0.026*
H16B	0.9330	0.2779	0.8371	0.026*
N1	0.81963 (11)	0.30046 (19)	0.95388 (7)	0.0238 (3)
H1	0.8897	0.3801	0.9550	0.029*
O1	0.44263 (10)	0.20911 (18)	1.07492 (6)	0.0347 (3)
O2	0.88904 (9)	0.59166 (16)	1.04622 (6)	0.0265 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0255 (8)	0.0203 (7)	0.0222 (8)	−0.0047 (6)	0.0055 (6)	−0.0034 (6)
C2	0.0224 (8)	0.0225 (7)	0.0214 (8)	−0.0028 (6)	0.0058 (6)	0.0004 (6)
C3	0.0203 (7)	0.0209 (7)	0.0151 (8)	0.0024 (6)	0.0014 (6)	0.0004 (6)
C4	0.0195 (7)	0.0299 (8)	0.0240 (9)	0.0020 (6)	0.0046 (6)	−0.0011 (7)
C5	0.0254 (8)	0.0322 (8)	0.0244 (9)	0.0057 (7)	0.0048 (6)	−0.0066 (7)
C6	0.0312 (8)	0.0256 (8)	0.0262 (9)	0.0045 (7)	0.0005 (7)	−0.0063 (7)
C7	0.0256 (8)	0.0216 (7)	0.0226 (8)	−0.0006 (6)	0.0023 (6)	−0.0013 (6)
C8	0.0211 (7)	0.0204 (7)	0.0150 (8)	0.0017 (6)	0.0015 (6)	0.0008 (6)
C9	0.0208 (7)	0.0196 (7)	0.0167 (8)	−0.0028 (6)	0.0036 (6)	0.0026 (6)
C10	0.0205 (7)	0.0211 (7)	0.0166 (8)	0.0001 (6)	0.0042 (6)	−0.0008 (6)
C11	0.0220 (7)	0.0221 (7)	0.0187 (8)	−0.0049 (6)	0.0075 (6)	−0.0048 (6)
C12	0.0358 (9)	0.0242 (8)	0.0235 (9)	−0.0030 (7)	0.0015 (7)	0.0015 (6)
C13	0.0363 (9)	0.0198 (8)	0.0387 (11)	0.0008 (7)	0.0015 (8)	−0.0048 (7)
C14	0.0238 (8)	0.0290 (8)	0.0347 (10)	0.0001 (7)	0.0056 (7)	−0.0136 (7)
C15	0.0281 (8)	0.0308 (8)	0.0212 (9)	−0.0047 (7)	0.0067 (6)	−0.0051 (7)
C16	0.0246 (7)	0.0207 (7)	0.0212 (8)	−0.0008 (6)	0.0055 (6)	−0.0005 (6)
N1	0.0245 (7)	0.0239 (6)	0.0249 (7)	−0.0095 (5)	0.0112 (5)	−0.0086 (5)
O1	0.0315 (6)	0.0334 (6)	0.0423 (8)	−0.0142 (5)	0.0190 (5)	−0.0103 (5)
O2	0.0237 (6)	0.0269 (6)	0.0301 (7)	−0.0069 (5)	0.0092 (4)	−0.0069 (5)

Geometric parameters (Å, º) top

C1—C10	1.3535 (19)	C11—N1	1.4281 (18)
C1—C2	1.433 (2)	C11—C12	1.477 (2)
C1—H1A	0.9500	C11—C16	1.519 (2)
C2—O1	1.2201 (16)	C11—H11	1.0000
C2—C3	1.457 (2)	C12—C13	1.494 (2)
C3—C4	1.378 (2)	C12—H12A	0.9900
C3—C8	1.3820 (19)	C12—H12B	0.9900
C4—C5	1.342 (2)	C13—C14	1.514 (2)
C4—H4	0.9500	C13—H13A	0.9900
C5—C6	1.367 (2)	C13—H13B	0.9900
C5—H5	0.9500	C14—C15	1.475 (2)
C6—C7	1.381 (2)	C14—H14A	0.9900
C6—H6	0.9500	C14—H14B	0.9900
C7—C8	1.349 (2)	C15—C16	1.495 (2)
C7—H7	0.9500	C15—H15A	0.9900
C8—C9	1.468 (2)	C15—H15B	0.9900
C9—O2	1.2120 (16)	C16—H16A	0.9900
C9—C10	1.464 (2)	C16—H16B	0.9900
C10—N1	1.3419 (18)	N1—H1	0.8800

C10—C1—C2	123.59 (13)	C16—C11—H11	108.8
C10—C1—H1A	118.2	C11—C12—C13	109.52 (13)
C2—C1—H1A	118.2	C11—C12—H12A	109.8
O1—C2—C1	123.94 (13)	C13—C12—H12A	109.8
O1—C2—C3	117.81 (13)	C11—C12—H12B	109.8
C1—C2—C3	118.23 (12)	C13—C12—H12B	109.8
C4—C3—C8	120.97 (13)	H12A—C12—H12B	108.2
C4—C3—C2	119.79 (13)	C12—C13—C14	113.14 (13)
C8—C3—C2	119.23 (13)	C12—C13—H13A	109.0
C5—C4—C3	119.67 (14)	C14—C13—H13A	108.9
C5—C4—H4	120.2	C12—C13—H13B	108.9
C3—C4—H4	120.2	C14—C13—H13B	108.9
C4—C5—C6	119.30 (15)	H13A—C13—H13B	107.8
C4—C5—H5	120.4	C15—C14—C13	109.90 (13)
C6—C5—H5	120.4	C15—C14—H14A	109.7
C5—C6—C7	121.76 (15)	C13—C14—H14A	109.7
C5—C6—H6	119.1	C15—C14—H14B	109.7
C7—C6—H6	119.1	C13—C14—H14B	109.7
C8—C7—C6	118.97 (14)	H14A—C14—H14B	108.2
C8—C7—H7	120.5	C14—C15—C16	109.05 (13)
C6—C7—H7	120.5	C14—C15—H15A	109.9
C7—C8—C3	119.27 (14)	C16—C15—H15A	109.9
C7—C8—C9	119.16 (13)	C14—C15—H15B	109.9
C3—C8—C9	121.57 (13)	C16—C15—H15B	109.9
O2—C9—C10	119.27 (13)	H15A—C15—H15B	108.3
O2—C9—C8	123.40 (13)	C15—C16—C11	112.98 (12)
C10—C9—C8	117.33 (12)	C15—C16—H16A	109.0
N1—C10—C1	128.03 (14)	C11—C16—H16A	109.0
N1—C10—C9	112.78 (12)	C15—C16—H16B	109.0
C1—C10—C9	119.19 (13)	C11—C16—H16B	109.0
N1—C11—C12	109.08 (12)	H16A—C16—H16B	107.8
N1—C11—C16	111.20 (12)	C10—N1—C11	126.73 (12)
C12—C11—C16	109.97 (12)	C10—N1—H1	116.6
N1—C11—H11	108.8	C11—N1—H1	116.6
C12—C11—H11	108.8

C10—C1—C2—O1	179.28 (14)	C3—C8—C9—C10	10.3 (2)
C10—C1—C2—C3	0.9 (2)	C2—C1—C10—N1	−174.88 (14)
O1—C2—C3—C4	−1.0 (2)	C2—C1—C10—C9	5.2 (2)
C1—C2—C3—C4	177.50 (14)	O2—C9—C10—N1	−11.0 (2)
O1—C2—C3—C8	−179.79 (13)	C8—C9—C10—N1	169.59 (12)
C1—C2—C3—C8	−1.3 (2)	O2—C9—C10—C1	168.95 (13)
C8—C3—C4—C5	1.7 (2)	C8—C9—C10—C1	−10.5 (2)
C2—C3—C4—C5	−177.05 (13)	N1—C11—C12—C13	−176.86 (12)
C3—C4—C5—C6	0.6 (2)	C16—C11—C12—C13	−54.66 (16)
C4—C5—C6—C7	−2.2 (2)	C11—C12—C13—C14	56.74 (18)
C5—C6—C7—C8	1.4 (2)	C12—C13—C14—C15	−57.82 (17)
C6—C7—C8—C3	1.0 (2)	C13—C14—C15—C16	56.06 (16)
C6—C7—C8—C9	−178.34 (13)	C14—C15—C16—C11	−57.67 (17)
C4—C3—C8—C7	−2.5 (2)	N1—C11—C16—C15	178.25 (12)
C2—C3—C8—C7	176.24 (13)	C12—C11—C16—C15	57.32 (16)
C4—C3—C8—C9	176.77 (13)	C1—C10—N1—C11	2.6 (2)
C2—C3—C8—C9	−4.4 (2)	C9—C10—N1—C11	−177.49 (13)
C7—C8—C9—O2	10.2 (2)	C12—C11—N1—C10	−99.26 (17)
C3—C8—C9—O2	−169.11 (13)	C16—C11—N1—C10	139.29 (15)
C7—C8—C9—C10	−170.40 (12)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2	0.88	2.19	2.5917 (16)	107

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