Dimethyl 2,6,8-trimethyl-1,2-dihydroquinoline-2,4-dicarboxylate

Gültekin, Z.; Frey, W.; Tercan, B.; Hökelek, T.

doi:10.1107/S160053681004153X

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 66| Part 11| November 2010| Pages o2891-o2892

https://doi.org/10.1107/S160053681004153X

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Dimethyl 2,6,8-trimethyl-1,2-dihydroquinoline-2,4-dicarboxylate

Zeynep Gültekin,^a Wolfgang Frey,^b Barış Tercan ^c and Tuncer Hökelek ^d ^*

^aDepartment of Chemistry, Çankırı Karatekin University, TR-18100, Çankırı, Turkey, ^bUniversität Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany, ^cDepartment of Physics, Karabük University, 78050 Karabük, Turkey, and ^dDepartment of Physics, Hacettepe University, 06800 Beytepe, Ankara, Turkey
^*Correspondence e-mail: merzifon@hacettepe.edu.tr

(Received 6 October 2010; accepted 14 October 2010; online 23 October 2010)

The title compound, C₁₆H₁₉NO₄, the hydrogenated ring adopts a twisted conformation. In the crystal, intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric R₂²(10) dimers. These dimers are further connected via intermolecular N—H⋯O hydrogen bonds, forming infinite double chains along [001].

Related literature

For the preparation of 1,2-dihydroquinoline, see: Edwards et al. (1998 ); Yan et al. (2004 ); Petasis & Butkevich (2009 ); Johnson et al. (1989 ); Waldmann et al. (2008 ); Rueping & Gültekin (2009 ). For the biological activity of dihydroquinolines, see: Elmore et al. (2001 ); Dillard et al. (1973 ); Muren & Weissmann (1971 ). For the preparation of quinolines, see: Dauphinee & Forrest (1978 ); Yan et al. (2004); Tom & Ruel (2001 ); Tokuyama et al. (2001 ); Sarma & Prajapati (2008 ); Martinez et al. (2008 ); Huang et al. (2009 ); Katritzky et al. (1996 ). For the biological activity of quinolines, see: Hamann et al. (1998 ); He et al. (2003 ); LaMontagne et al. (1989 ). For graph-set analysis, see: Bernstein et al. (1995 ). For ring puckering parameters, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₁₆H₁₉NO₄
M_r = 289.33
Monoclinic, P 2₁ /n
a = 7.7944 (5) Å
b = 23.4621 (8) Å
c = 8.2551 (5) Å
β = 93.729 (5)°
V = 1506.44 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 294 K
0.45 × 0.35 × 0.05 mm

Data collection

Nicolet P3 diffractometer
3188 measured reflections
2971 independent reflections
1999 reflections with I > 2σ(I)
R_int = 0.030
3 standard reflections every 50 reflections intensity decay: 2%

Refinement

R[F² > 2σ(F²)] = 0.056
wR(F²) = 0.144
S = 1.07
2971 reflections
244 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.91 (3)	2.30 (3)	3.190 (3)	166 (3)
C2—H2⋯O4ⁱⁱ	0.94 (3)	2.54 (3)	3.444 (3)	162 (2)
Symmetry codes: (i) x, y, z+1; (ii) -x+2, -y+1, -z.

Data collection: XSCANS (Siemens, 1996 ); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 2008 ); 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 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S160053681004153X/su2218sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681004153X/su2218Isup2.hkl

checkCIF report

Comment top

Dihydroquinolines have been widely studied and found an important structural unit in synthetic organic and medicinal chemistry (Elmore et al., 2001; Dillard et al., 1973; Muren & Weissmann, 1971). Many dihydroquinoline derivatives have been reported in the literature (Edwards et al., 1998; Yan et al., 2004; Petasis & Butkevich, 2009) and some of them have biological effects. For example, 2,2,4-substituted 1,2-dihydroquinolines have been shown antibacterial activities (Johnson et al., 1989). They are also powerful intermediates for the preparation of quinolines (Dauphinee & Forrest, 1978; Yan et al., 2004; Tom & Ruel, 2001; Tokuyama et al., 2001) and 1,2,3,4-tetrahydroquinolines (Katritzky et al., 1996). Many synthetic methods have been developed for the preparation of quinolines (Sarma & Prajapati, 2008; Martinez et al., 2008; Huang et al., 2009) and many quinolines display biological effects (Hamann et al., 1998; He et al., 2003; LaMontagne et al., 1989).

In the title molecule, illustrated in Fig. 1, ring A (C1-C4/C9/N1) is not planar with the puckering parameters (Cremer & Pople, 1975) Q_T = 0.358 (2) Å, φ = 155.3 (4)° and θ = 67.1 (4)°.

In the crystal of the title compound intermolecular C-H···O hydrogen bonds (Table 1) link the molecules into R₂²(10) dimers centered about an inversion center (Bernstein et al., 1995). These dimers are further connected via intermolecular N-H···O hydrogen bonds (Table 1) to form infinite double chains propagating along [001] (Fig. 2).

Related literature top

For the preparation of 1,2-dihydroquinoline, see: Edwards et al. (1998); Yan et al. (2004); Petasis & Butkevich (2009); Johnson et al. (1989); Waldmann et al. (2008); Rueping & Gültekin (2009). For the biological activity of dihydroquinolines, see: Elmore et al. (2001); Dillard et al. (1973); Muren & Weissmann (1971). For the preparation of quinolines, see: Dauphinee & Forrest (1978); Yan et al. (2004); Tom & Ruel (2001); Tokuyama et al. (2001); Sarma & Prajapati (2008); Martinez et al. (2008); Huang et al. (2009); Katritzky et al. (1996). For the biological activity of quinolines, see: Hamann et al. (1998); He et al. (2003); LaMontagne et al. (1989). For graph-set analysis, see: Bernstein et al. (1995). For ring puckering parameters, see: Cremer & Pople (1975).

Experimental top

The title compound was synthesized by the literature method (Waldmann et al., 2008). 2,4-dimethylaniline (100 mg, 1 eq) was dissolved in chloroform (1.5 ml) in a screw-capped test tube and Bi(OTf)₃ (5 mol%, 0.05 eq) was added to the mixture. The mixture was stirred at room temperature for 6 d until the starting material was completely consumed as monitored by TLC. The resultant residue was directly purified by flash chromatography on silica (EtOAc:Cylohexane 2:98) and gave, in 60% yield, a pale yellow solid. This solid was recrystallized over pentane and ethyl acetate (70:30) to give a pale yellow crystalline solid; R_f 0.25 (2:1 Cyclohexanone/EtOAc); mp. 420-421 K (Rueping & Gültekin, 2009).

Structure description top

In the title molecule, illustrated in Fig. 1, ring A (C1-C4/C9/N1) is not planar with the puckering parameters (Cremer & Pople, 1975) Q_T = 0.358 (2) Å, φ = 155.3 (4)° and θ = 67.1 (4)°.

For the preparation of 1,2-dihydroquinoline, see: Edwards et al. (1998); Yan et al. (2004); Petasis & Butkevich (2009); Johnson et al. (1989); Waldmann et al. (2008); Rueping & Gültekin (2009). For the biological activity of dihydroquinolines, see: Elmore et al. (2001); Dillard et al. (1973); Muren & Weissmann (1971). For the preparation of quinolines, see: Dauphinee & Forrest (1978); Yan et al. (2004); Tom & Ruel (2001); Tokuyama et al. (2001); Sarma & Prajapati (2008); Martinez et al. (2008); Huang et al. (2009); Katritzky et al. (1996). For the biological activity of quinolines, see: Hamann et al. (1998); He et al. (2003); LaMontagne et al. (1989). For graph-set analysis, see: Bernstein et al. (1995). For ring puckering parameters, see: Cremer & Pople (1975).

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: SHELXTL (Sheldrick, 2008); 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) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A partial packing diagram, viewed down the a-axis, of the title compound. Hydrogen bonds are shown as dashed cyan lines (see Table 1 for details).

Dimethyl 2,6,8-trimethyl-1,2-dihydroquinoline-2,4-dicarboxylate top

Crystal data top

C₁₆H₁₉NO₄	F(000) = 616
M_r = 289.33	D_x = 1.276 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 26 reflections
a = 7.7944 (5) Å	θ = 12–14°
b = 23.4621 (8) Å	µ = 0.09 mm⁻¹
c = 8.2551 (5) Å	T = 294 K
β = 93.729 (5)°	Plate, pale yellow
V = 1506.44 (14) Å³	0.45 × 0.35 × 0.05 mm
Z = 4

Data collection top

Nicolet P3 diffractometer	R_int = 0.030
Radiation source: fine-focus sealed tube	θ_max = 26.0°, θ_min = 1.7°
Graphite monochromator	h = 0→9
Wyckoff–Scan scans	k = 0→28
3188 measured reflections	l = −10→10
2971 independent reflections	3 standard reflections every 50 reflections
1999 reflections with I > 2σ(I)	intensity decay: 2%

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.144	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ²(F_o²) + (0.0504P)² + 0.6624P] where P = (F_o² + 2F_c²)/3
2971 reflections	(Δ/σ)_max < 0.001
244 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₆H₁₉NO₄	V = 1506.44 (14) Å³
M_r = 289.33	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 7.7944 (5) Å	µ = 0.09 mm⁻¹
b = 23.4621 (8) Å	T = 294 K
c = 8.2551 (5) Å	0.45 × 0.35 × 0.05 mm
β = 93.729 (5)°

Data collection top

Nicolet P3 diffractometer	R_int = 0.030
3188 measured reflections	3 standard reflections every 50 reflections
2971 independent reflections	intensity decay: 2%
1999 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.056	0 restraints
wR(F²) = 0.144	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	Δρ_max = 0.19 e Å⁻³
2971 reflections	Δρ_min = −0.21 e Å⁻³
244 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.7764 (3)	0.59692 (11)	−0.3063 (2)	0.0640 (6)
O2	0.5173 (2)	0.61471 (9)	−0.2180 (2)	0.0502 (5)
O3	1.1234 (3)	0.60687 (11)	0.3726 (3)	0.0738 (7)
O4	1.1641 (2)	0.56175 (9)	0.1411 (2)	0.0539 (6)
N1	0.7690 (3)	0.60501 (9)	0.3076 (3)	0.0393 (5)
H1	0.792 (4)	0.6030 (12)	0.417 (4)	0.054 (9)*
C1	0.7476 (3)	0.61554 (11)	−0.0238 (3)	0.0334 (5)
C2	0.8247 (3)	0.56972 (11)	0.0436 (3)	0.0352 (6)
H2	0.849 (3)	0.5376 (11)	−0.018 (3)	0.035 (7)*
C3	0.8769 (3)	0.56643 (10)	0.2214 (3)	0.0353 (6)
C4	0.7347 (3)	0.65906 (11)	0.2432 (3)	0.0341 (5)
C5	0.7101 (3)	0.70451 (12)	0.3481 (3)	0.0415 (6)
H5	0.733 (3)	0.6993 (10)	0.464 (3)	0.033 (6)*
C6	0.6669 (3)	0.75784 (12)	0.2865 (3)	0.0447 (7)
C7	0.6494 (4)	0.76513 (12)	0.1202 (4)	0.0466 (7)
H7	0.620 (3)	0.8011 (12)	0.074 (3)	0.046 (8)*
C8	0.6763 (3)	0.72106 (11)	0.0118 (3)	0.0403 (6)
C9	0.7161 (3)	0.66663 (11)	0.0741 (3)	0.0342 (5)
C10	0.6878 (3)	0.60882 (11)	−0.1978 (3)	0.0389 (6)
C11	0.4423 (5)	0.60908 (19)	−0.3831 (4)	0.0605 (9)
H111	0.475 (5)	0.6429 (16)	−0.448 (4)	0.084 (12)*
H112	0.485 (5)	0.5743 (16)	−0.428 (4)	0.077 (12)*
H113	0.322 (6)	0.6056 (16)	−0.371 (5)	0.095 (13)*
C12	0.8522 (4)	0.50594 (13)	0.2861 (4)	0.0500 (7)
H121	0.873 (4)	0.5072 (12)	0.407 (4)	0.057 (9)*
H123	0.734 (4)	0.4934 (13)	0.252 (4)	0.064 (9)*
H122	0.926 (4)	0.4786 (14)	0.238 (4)	0.070 (10)*
C13	1.0681 (3)	0.58165 (11)	0.2556 (3)	0.0376 (6)
C14	1.3481 (4)	0.57041 (17)	0.1667 (5)	0.0720 (10)
H14A	1.4029	0.5604	0.0698	0.108*
H14B	1.3924	0.5468	0.2549	0.108*
H14C	1.3709	0.6097	0.1924	0.108*
C15	0.6472 (6)	0.80746 (16)	0.4010 (5)	0.0637 (9)
H151	0.582 (6)	0.7969 (18)	0.496 (5)	0.108 (15)*
H152	0.588 (6)	0.840 (2)	0.347 (5)	0.115 (16)*
H153	0.754 (6)	0.8168 (18)	0.450 (5)	0.109 (16)*
C16	0.6685 (4)	0.73525 (12)	−0.1667 (3)	0.0536 (8)
H16A	0.7586	0.7154	−0.2172	0.080*
H16B	0.6828	0.7756	−0.1802	0.080*
H16C	0.5591	0.7238	−0.2163	0.080*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0579 (13)	0.0996 (18)	0.0346 (11)	0.0201 (12)	0.0036 (9)	−0.0042 (11)
O2	0.0363 (10)	0.0755 (14)	0.0376 (10)	−0.0025 (9)	−0.0070 (8)	0.0008 (9)
O3	0.0470 (12)	0.106 (2)	0.0664 (15)	−0.0009 (12)	−0.0122 (11)	−0.0370 (14)
O4	0.0303 (9)	0.0749 (14)	0.0564 (12)	−0.0054 (9)	0.0028 (8)	−0.0166 (10)
N1	0.0414 (12)	0.0463 (13)	0.0301 (11)	0.0068 (10)	0.0026 (9)	0.0048 (10)
C1	0.0252 (11)	0.0435 (14)	0.0316 (12)	−0.0012 (10)	0.0020 (9)	−0.0001 (10)
C2	0.0292 (12)	0.0376 (14)	0.0385 (14)	−0.0003 (10)	−0.0001 (10)	−0.0036 (11)
C3	0.0321 (13)	0.0362 (13)	0.0372 (13)	0.0009 (10)	−0.0006 (10)	0.0014 (11)
C4	0.0245 (11)	0.0414 (14)	0.0365 (12)	0.0002 (10)	0.0029 (9)	0.0015 (11)
C5	0.0391 (14)	0.0533 (17)	0.0326 (14)	0.0000 (12)	0.0064 (11)	−0.0036 (12)
C6	0.0367 (14)	0.0442 (16)	0.0538 (17)	0.0013 (12)	0.0085 (12)	−0.0081 (13)
C7	0.0454 (15)	0.0377 (15)	0.0563 (18)	0.0041 (12)	0.0013 (13)	0.0031 (13)
C8	0.0360 (13)	0.0437 (15)	0.0411 (14)	0.0009 (11)	0.0015 (11)	0.0032 (12)
C9	0.0282 (11)	0.0398 (14)	0.0344 (13)	0.0003 (10)	0.0016 (10)	−0.0004 (10)
C10	0.0385 (13)	0.0449 (15)	0.0330 (13)	0.0026 (11)	−0.0014 (11)	−0.0008 (11)
C11	0.056 (2)	0.078 (3)	0.0452 (18)	−0.0146 (19)	−0.0160 (15)	0.0065 (18)
C12	0.0518 (18)	0.0420 (17)	0.0555 (19)	−0.0044 (14)	−0.0012 (15)	0.0088 (14)
C13	0.0371 (13)	0.0382 (14)	0.0365 (13)	0.0019 (11)	−0.0047 (10)	0.0003 (11)
C14	0.0314 (15)	0.102 (3)	0.083 (2)	−0.0042 (17)	0.0006 (15)	−0.008 (2)
C15	0.068 (2)	0.055 (2)	0.070 (2)	0.0065 (18)	0.014 (2)	−0.0184 (18)
C16	0.066 (2)	0.0452 (17)	0.0492 (17)	0.0033 (14)	0.0014 (14)	0.0094 (13)

Geometric parameters (Å, º) top

O1—C10	1.199 (3)	C6—C15	1.513 (4)
O2—C10	1.336 (3)	C7—H7	0.95 (3)
O2—C11	1.454 (3)	C8—C7	1.392 (4)
O3—C13	1.189 (3)	C8—C16	1.508 (4)
O4—C13	1.328 (3)	C9—C8	1.404 (3)
O4—C14	1.450 (3)	C11—H111	1.00 (4)
N1—C3	1.453 (3)	C11—H112	0.96 (4)
N1—C4	1.394 (3)	C11—H113	0.95 (4)
N1—H1	0.91 (3)	C12—H121	1.01 (3)
C1—C2	1.335 (3)	C12—H122	0.97 (3)
C1—C9	1.475 (3)	C12—H123	0.99 (3)
C1—C10	1.490 (3)	C14—H14A	0.9600
C2—H2	0.94 (3)	C14—H14B	0.9600
C3—C2	1.499 (3)	C14—H14C	0.9600
C3—C12	1.533 (4)	C15—H151	0.99 (4)
C3—C13	1.541 (3)	C15—H153	0.93 (5)
C4—C5	1.395 (4)	C15—H152	0.98 (5)
C4—C9	1.405 (3)	C16—H16A	0.9600
C5—H5	0.97 (2)	C16—H16B	0.9600
C6—C5	1.384 (4)	C16—H16C	0.9600
C6—C7	1.381 (4)

C10—O2—C11	116.3 (2)	O1—C10—C1	125.8 (2)
C13—O4—C14	116.4 (2)	O2—C10—C1	110.9 (2)
C3—N1—H1	111.9 (19)	O2—C11—H111	109 (2)
C4—N1—C3	118.9 (2)	O2—C11—H112	108 (2)
C4—N1—H1	116.5 (18)	O2—C11—H113	104 (2)
C2—C1—C9	120.9 (2)	H111—C11—H112	111 (3)
C2—C1—C10	114.9 (2)	H113—C11—H111	114 (3)
C9—C1—C10	124.1 (2)	H113—C11—H112	110 (3)
C1—C2—C3	122.4 (2)	C3—C12—H121	107.6 (17)
C1—C2—H2	121.5 (15)	C3—C12—H122	112.1 (19)
C3—C2—H2	116.2 (15)	C3—C12—H123	108.2 (18)
N1—C3—C2	108.6 (2)	H121—C12—H122	112 (3)
N1—C3—C12	108.4 (2)	H121—C12—H123	112 (2)
N1—C3—C13	110.5 (2)	H123—C12—H122	105 (3)
C2—C3—C12	110.9 (2)	O3—C13—O4	124.2 (2)
C2—C3—C13	111.4 (2)	O3—C13—C3	124.0 (2)
C12—C3—C13	107.0 (2)	O4—C13—C3	111.8 (2)
N1—C4—C5	119.3 (2)	O4—C14—H14A	109.5
N1—C4—C9	119.9 (2)	O4—C14—H14B	109.5
C5—C4—C9	120.7 (2)	O4—C14—H14C	109.5
C4—C5—H5	119.5 (15)	H14A—C14—H14B	109.5
C6—C5—C4	120.2 (2)	H14A—C14—H14C	109.5
C6—C5—H5	120.1 (15)	H14B—C14—H14C	109.5
C5—C6—C15	119.9 (3)	C6—C15—H151	112 (3)
C7—C6—C5	118.9 (3)	C6—C15—H152	112 (3)
C7—C6—C15	121.2 (3)	C6—C15—H153	109 (3)
C6—C7—C8	122.5 (3)	H151—C15—H152	108 (4)
C6—C7—H7	121.0 (16)	H151—C15—H153	102 (4)
C8—C7—H7	116.5 (16)	H153—C15—H152	113 (4)
C7—C8—C9	118.6 (2)	C8—C16—H16A	109.5
C7—C8—C16	117.8 (2)	C8—C16—H16B	109.5
C9—C8—C16	123.5 (2)	C8—C16—H16C	109.5
C4—C9—C1	115.5 (2)	H16A—C16—H16B	109.5
C8—C9—C1	125.4 (2)	H16A—C16—H16C	109.5
C8—C9—C4	119.0 (2)	H16B—C16—H16C	109.5
O1—C10—O2	123.2 (2)

C11—O2—C10—O1	−3.4 (4)	N1—C3—C13—O3	23.5 (4)
C11—O2—C10—C1	180.0 (3)	N1—C3—C13—O4	−158.4 (2)
C14—O4—C13—O3	2.1 (4)	C2—C3—C13—O3	144.2 (3)
C14—O4—C13—C3	−176.1 (2)	C2—C3—C13—O4	−37.6 (3)
C4—N1—C3—C2	−43.0 (3)	C12—C3—C13—O3	−94.4 (3)
C4—N1—C3—C12	−163.6 (2)	C12—C3—C13—O4	83.7 (3)
C4—N1—C3—C13	79.5 (3)	N1—C4—C5—C6	−176.6 (2)
C3—N1—C4—C5	−148.5 (2)	C9—C4—C5—C6	0.0 (4)
C3—N1—C4—C9	34.8 (3)	N1—C4—C9—C1	−4.2 (3)
C9—C1—C2—C3	2.5 (4)	N1—C4—C9—C8	178.1 (2)
C10—C1—C2—C3	−173.5 (2)	C5—C4—C9—C1	179.2 (2)
C2—C1—C9—C4	−14.1 (3)	C5—C4—C9—C8	1.5 (4)
C2—C1—C9—C8	163.4 (2)	C7—C6—C5—C4	−0.3 (4)
C10—C1—C9—C4	161.5 (2)	C15—C6—C5—C4	−177.6 (3)
C10—C1—C9—C8	−21.0 (4)	C5—C6—C7—C8	−1.0 (4)
C2—C1—C10—O1	−58.1 (4)	C15—C6—C7—C8	176.3 (3)
C2—C1—C10—O2	118.4 (2)	C9—C8—C7—C6	2.6 (4)
C9—C1—C10—O1	126.0 (3)	C16—C8—C7—C6	−174.9 (3)
C9—C1—C10—O2	−57.5 (3)	C1—C9—C8—C7	179.8 (2)
N1—C3—C2—C1	24.7 (3)	C1—C9—C8—C16	−2.9 (4)
C12—C3—C2—C1	143.8 (3)	C4—C9—C8—C7	−2.7 (4)
C13—C3—C2—C1	−97.2 (3)	C4—C9—C8—C16	174.5 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.91 (3)	2.30 (3)	3.190 (3)	166 (3)
C2—H2···O4ⁱⁱ	0.94 (3)	2.54 (3)	3.444 (3)	162 (2)

Symmetry codes: (i) x, y, z+1; (ii) −x+2, −y+1, −z.

Experimental details

Crystal data
Chemical formula	C₁₆H₁₉NO₄
M_r	289.33
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	294
a, b, c (Å)	7.7944 (5), 23.4621 (8), 8.2551 (5)
β (°)	93.729 (5)
V (Å³)	1506.44 (14)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.45 × 0.35 × 0.05

Data collection
Diffractometer	Nicolet P3
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	3188, 2971, 1999
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.144, 1.07
No. of reflections	2971
No. of parameters	244
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.21

Computer programs: XSCANS (Siemens, 1996), SHELXTL (Sheldrick, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006), WinGX publication routines (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.91 (3)	2.30 (3)	3.190 (3)	166 (3)
C2—H2···O4ⁱⁱ	0.94 (3)	2.54 (3)	3.444 (3)	162 (2)

Symmetry codes: (i) x, y, z+1; (ii) −x+2, −y+1, −z.

Acknowledgements

The authors thank Professor Magnus Rueping of RWTH Aachen University, Germany, for helpful discussions.

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