Ethyl 2-(3,5-dimethyl-1,1-dioxo-2H-1λ6,2,6-thia­diazin-4-yl)benzoate

Bhatt, N.; Bhatt, P.; Vyas, K.B.; Nimavat, K.; Govender, T.; Kruger, H.G.; Maguire, G.E.M.

doi:10.1107/S1600536812024907

organic compounds

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Volume 68| Part 7| July 2012| Page o2160

https://doi.org/10.1107/S1600536812024907

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Ethyl 2-(3,5-dimethyl-1,1-dioxo-2H-1λ⁶,2,6-thiadiazin-4-yl)benzoate

Nilay Bhatt,^a Pralav Bhatt,^b Kartik B. Vyas,^c Kiran Nimavat,^d Thavendran Govender,^e Hendrik G. Kruger ^b and Glenn E. M. Maguire ^b ^*

^aChemistry Department, JJT University, Rajasthan, India, ^bSchool of Chemistry, University of KwaZulu-Natal, Durban 4000, South Africa, ^cSheth L.H. Science College, Mansa, Gujarat, India, ^dDepartment of Chemistry, Government Science College, Gandhinagar, Gujarat, India, and ^eSchool of Pharmacology, University of KwaZulu-Natal, Westville Campus, Private Bag-X54001, Durban, South Africa
^*Correspondence e-mail: maguireg@ukzn.ac.za

(Received 1 May 2012; accepted 31 May 2012; online 20 June 2012)

In the title compound, C₁₄H₁₆N₂O₄S, the thiadiazine ring is in a half-boat conformation. The aromatic ring deviates from the plane of this moiety at an angle of 74.6 (2)°. The structure displays intermolecular N—H⋯O hydrogen bonding [N⋯O = 2.8157 (16) Å], creating ribbons along the [010] axis. There are also weak C—H⋯O interactions in the crystal but no π–π stacking.

Related literature

For the synthesis of 1,2,6-thiadiazine-1,1-dioxide derivatives, see: Wright (1964 ); Ochoa & Stud (1978 ). For the biological activity of 1,2,6-thiadiazine-1,1-dioxide derivatives, see: Aran et al. (1986 ); Herrero et al. (1992 ); Breining et al. (1995 ); Campillo et al. (2000 ). For related structures, see: Elguero et al. (1982 ).

Experimental

Crystal data

C₁₄H₁₆N₂O₄S
M_r = 308.35
Monoclinic, P 2₁
a = 10.3943 (2) Å
b = 6.6089 (2) Å
c = 10.6563 (3) Å
β = 94.982 (2)°
V = 729.27 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 173 K
0.25 × 0.24 × 0.23 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ) T_min = 0.943, T_max = 0.947
3321 measured reflections
3321 independent reflections
3083 reflections with I > 2σ(I)
R_int = 0.013

Refinement

R[F² > 2σ(F²)] = 0.027
wR(F²) = 0.067
S = 1.08
3321 reflections
198 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.22 e Å⁻³
Absolute structure: Flack (1983 ) 1512 Friedel pairs
Flack parameter: −0.03 (5)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O3ⁱ	0.97 (2)	1.85 (2)	2.8157 (16)	175 (2)
C5—H5A⋯O1ⁱⁱ	0.98	2.52	3.310 (2)	137
Symmetry codes: (i) $[-x, y+{\script{1\over 2}}, -z]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z]$ .

Data collection: COLLECT (Nonius, 2000 ); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812024907/hg5223sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812024907/hg5223Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536812024907/hg5223Isup3.cml

checkCIF report

Comment top

The synthesis of 1,2,6-thiadiazine-1,1-dioxides derivatives was first reported using sulfamide with alpha and beta diketones (Wright, 1964). Purine and pyrimidine nucleotide versions of this structure have also been synthesized (Ochoa & Stud, 1978). More recently 1,2,6-thiadiazine-1,1-dioxide derivatives have since been reported to posses antiparasitic (Aran et al., 1986), antiprotozoal (Herrero et al., 1992), anti-HIV-1 activity (Breining et al., 1995) and also act as bronchodilators (Campillo et al., 2000).

The first single-crystal X-ray structure of a 3,5 dimethyl-1,2,6-thiadiazine-1,1-dioxide derivative was reported by Elguero et al., 1982. The structure displayed intermolecular hydrogen bonding at N(2)—H(1)—O(2), 2.904 Å. The title compound is the first 3,5 dimethyl based structure reported with an aromatic ring at position 4 of the thiadiazine ring. It is also the first containing an ester functional group in the broader family of 1,2,6-thiadiazine-1,1-dioxides. The sulfur atom deviates from the plane of the ring by 0.53 Å (Fig. 1). The aromatic ring is nearly orthogonal to the thiadiazine ring with an angle of 74.6 (2)° from the plane. The structure displays intermolecular hydrogen bonding N(1)—H(1)—O(3), 2.8157 (16)Å creating ribbons along the [010] axis (Fig. 2). There is no π -π stacking in the crystal structure.

Related literature top

For the synthesis of 1,2,6-thiadiazine-1,1-dioxide derivatives, see: Wright (1964); Ochoa & Stud (1978), . For the biological activities of 1,2,6-thiadiazine-1,1-dioxide derivatives, see: Aran et al. (1986); Herrero et al. (1992); Breining et al. (1995); Campillo et al. (2000). For related structures, see: Elguero et al., (1982).

Experimental top

To ethanol (25 ml) and 2-(3,5-dimethyl-1,1-dioxo-2H-1,2,6-thiadiazin-4-yl) benzoic acid (10 mM) was slowly added thionyl chloride (50 mM), the contents were refluxed for 4 h, untill the reaction was complete (TLC R_f = 0.7 in 80% ethyl acetate/hexane). The contents were filtered. The filtrate was evaporated under reduced pressure yielding a clear oil. To this residue was added a solution of ethanol/ethyl acetate, (10 ml) (10/90) to yield a white colourless solid (55%). M.p.= 417.5 K.

Crystals suitable for X-ray analysis were grown in methanol/ethyl acetate at room temprature.

Structure description top

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound with atomic numbering scheme. The H atoms have been omitted for clarity. Displacement ellipsoids are drawn at 40% probability.
	Fig. 2. The hydrogen bonding ineractions of the title compound along the [111] axis. All H atoms except those involved in hydrogen bonding interactions have been omitted for clarity.

Ethyl 2-(3,5-dimethyl-1,1-dioxo-2H-1λ⁶,2,6-thiadiazin-4-yl)benzoate top

Crystal data top

C₁₄H₁₆N₂O₄S	F(000) = 324
M_r = 308.35	D_x = 1.404 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 3321 reflections
a = 10.3943 (2) Å	θ = 3.6–27.5°
b = 6.6089 (2) Å	µ = 0.24 mm⁻¹
c = 10.6563 (3) Å	T = 173 K
β = 94.982 (2)°	Block, colourless
V = 729.27 (3) Å³	0.25 × 0.24 × 0.23 mm
Z = 2

Data collection top

Nonius KappaCCD diffractometer	3321 independent reflections
Radiation source: fine-focus sealed tube	3083 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.013
1.2° φ scans and ω scans	θ_max = 27.5°, θ_min = 3.6°
Absorption correction: multi-scan (SADABS; Bruker, 2006)	h = −13→13
T_min = 0.943, T_max = 0.947	k = −8→8
3321 measured reflections	l = −13→13

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.027	w = 1/[σ²(F_o²) + (0.0356P)² + 0.1059P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.067	(Δ/σ)_max < 0.001
S = 1.08	Δρ_max = 0.22 e Å⁻³
3321 reflections	Δρ_min = −0.22 e Å⁻³
198 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.021 (3)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983) ???? Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.03 (5)

Crystal data top

C₁₄H₁₆N₂O₄S	V = 729.27 (3) Å³
M_r = 308.35	Z = 2
Monoclinic, P2₁	Mo Kα radiation
a = 10.3943 (2) Å	µ = 0.24 mm⁻¹
b = 6.6089 (2) Å	T = 173 K
c = 10.6563 (3) Å	0.25 × 0.24 × 0.23 mm
β = 94.982 (2)°

Data collection top

Nonius KappaCCD diffractometer	3321 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2006)	3083 reflections with I > 2σ(I)
T_min = 0.943, T_max = 0.947	R_int = 0.013
3321 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.027	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.067	Δρ_max = 0.22 e Å⁻³
S = 1.08	Δρ_min = −0.22 e Å⁻³
3321 reflections	Absolute structure: Flack (1983) ???? Friedel pairs
198 parameters	Absolute structure parameter: −0.03 (5)
2 restraints

Special details top

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
S1	0.22417 (3)	0.66320 (6)	−0.19373 (3)	0.02436 (10)
O1	0.32997 (11)	0.7730 (2)	−0.23716 (11)	0.0362 (3)
O2	0.13244 (11)	0.58238 (18)	−0.28774 (10)	0.0343 (3)
O3	0.07360 (10)	0.52605 (18)	0.21011 (10)	0.0305 (3)
O4	0.04265 (9)	0.69099 (17)	0.38957 (9)	0.0245 (2)
N1	0.14372 (11)	0.81211 (19)	−0.10443 (11)	0.0228 (3)
H1	0.0717 (13)	0.887 (3)	−0.1454 (17)	0.049 (6)*
N2	0.27760 (12)	0.4887 (2)	−0.09828 (12)	0.0287 (3)
C1	0.11769 (16)	1.0140 (3)	0.07966 (15)	0.0323 (4)
H1A	0.0268	0.9787	0.0850	0.048*
H1B	0.1233	1.1368	0.0288	0.048*
H1C	0.1591	1.0381	0.1645	0.048*
C2	0.18463 (13)	0.8442 (2)	0.01961 (13)	0.0209 (3)
C3	0.27298 (13)	0.7164 (2)	0.08085 (13)	0.0206 (3)
C4	0.30819 (13)	0.5334 (2)	0.02143 (14)	0.0244 (3)
C5	0.37968 (18)	0.3714 (3)	0.09778 (16)	0.0377 (4)
H5A	0.4693	0.4140	0.1186	0.057*
H5B	0.3784	0.2457	0.0489	0.057*
H5C	0.3380	0.3487	0.1756	0.057*
C6	0.32137 (14)	0.7514 (2)	0.21576 (13)	0.0226 (3)
C7	0.24812 (13)	0.7118 (2)	0.31791 (12)	0.0207 (3)
C8	0.30187 (14)	0.7466 (2)	0.44105 (13)	0.0243 (3)
H8	0.2517	0.7216	0.5098	0.029*
C9	0.42703 (15)	0.8167 (3)	0.46405 (14)	0.0284 (3)
H9	0.4634	0.8364	0.5481	0.034*
C10	0.49884 (15)	0.8579 (3)	0.36372 (15)	0.0313 (4)
H10	0.5843	0.9086	0.3788	0.038*
C11	0.44671 (14)	0.8255 (3)	0.24139 (14)	0.0296 (3)
H11	0.4973	0.8543	0.1734	0.036*
C12	0.11380 (13)	0.6337 (2)	0.29881 (12)	0.0222 (3)
C13	−0.08984 (13)	0.6165 (2)	0.38507 (14)	0.0269 (3)
H13A	−0.0908	0.4668	0.3881	0.032*
H13B	−0.1394	0.6610	0.3064	0.032*
C14	−0.14763 (15)	0.7028 (3)	0.49745 (14)	0.0309 (4)
H14A	−0.1467	0.8509	0.4928	0.046*
H14B	−0.0971	0.6586	0.5745	0.046*
H14C	−0.2369	0.6554	0.4986	0.046*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.02388 (17)	0.0332 (2)	0.01587 (16)	0.00301 (16)	0.00125 (11)	−0.00161 (15)
O1	0.0280 (6)	0.0546 (7)	0.0272 (6)	−0.0033 (5)	0.0091 (5)	0.0012 (5)
O2	0.0371 (6)	0.0418 (7)	0.0223 (5)	0.0019 (5)	−0.0074 (5)	−0.0080 (5)
O3	0.0283 (5)	0.0411 (7)	0.0221 (5)	−0.0120 (5)	0.0017 (4)	−0.0079 (5)
O4	0.0196 (4)	0.0317 (6)	0.0224 (5)	−0.0035 (4)	0.0033 (4)	−0.0038 (5)
N1	0.0220 (6)	0.0292 (7)	0.0169 (6)	0.0044 (5)	0.0001 (4)	0.0016 (5)
N2	0.0318 (7)	0.0337 (7)	0.0203 (6)	0.0090 (6)	0.0013 (5)	−0.0023 (5)
C1	0.0378 (9)	0.0303 (9)	0.0288 (8)	0.0088 (7)	0.0025 (7)	−0.0046 (7)
C2	0.0210 (7)	0.0248 (7)	0.0170 (7)	−0.0015 (6)	0.0030 (5)	−0.0003 (6)
C3	0.0184 (6)	0.0282 (8)	0.0153 (6)	−0.0006 (5)	0.0016 (5)	0.0006 (5)
C4	0.0204 (7)	0.0310 (8)	0.0217 (7)	0.0042 (6)	0.0025 (5)	0.0026 (6)
C5	0.0416 (10)	0.0385 (10)	0.0317 (9)	0.0143 (8)	−0.0046 (7)	0.0036 (7)
C6	0.0218 (7)	0.0278 (7)	0.0178 (7)	0.0009 (6)	−0.0002 (5)	0.0017 (6)
C7	0.0218 (6)	0.0225 (8)	0.0175 (6)	−0.0007 (5)	−0.0007 (5)	−0.0009 (5)
C8	0.0278 (7)	0.0284 (8)	0.0164 (7)	−0.0008 (6)	0.0009 (5)	−0.0006 (6)
C9	0.0286 (8)	0.0337 (8)	0.0216 (7)	−0.0037 (7)	−0.0051 (6)	−0.0019 (6)
C10	0.0230 (7)	0.0416 (10)	0.0282 (8)	−0.0078 (7)	−0.0042 (6)	0.0004 (7)
C11	0.0232 (7)	0.0420 (9)	0.0238 (8)	−0.0039 (7)	0.0027 (6)	0.0016 (7)
C12	0.0240 (7)	0.0255 (8)	0.0169 (6)	−0.0020 (6)	0.0010 (5)	0.0023 (6)
C13	0.0201 (7)	0.0315 (9)	0.0290 (8)	−0.0046 (6)	0.0016 (5)	−0.0024 (6)
C14	0.0263 (7)	0.0362 (10)	0.0310 (8)	−0.0025 (6)	0.0062 (6)	−0.0002 (7)

Geometric parameters (Å, º) top

S1—O2	1.4255 (11)	C5—H5B	0.9800
S1—O1	1.4279 (12)	C5—H5C	0.9800
S1—N2	1.6046 (14)	C6—C11	1.396 (2)
S1—N1	1.6466 (12)	C6—C7	1.406 (2)
O3—C12	1.2269 (17)	C7—C8	1.3998 (18)
O4—C12	1.3229 (17)	C7—C12	1.4859 (19)
O4—C13	1.4593 (16)	C8—C9	1.383 (2)
N1—C2	1.3694 (18)	C8—H8	0.9500
N1—H1	0.9697 (10)	C9—C10	1.383 (2)
N2—C4	1.3210 (19)	C9—H9	0.9500
C1—C2	1.494 (2)	C10—C11	1.384 (2)
C1—H1A	0.9800	C10—H10	0.9500
C1—H1B	0.9800	C11—H11	0.9500
C1—H1C	0.9800	C13—C14	1.498 (2)
C2—C3	1.3707 (19)	C13—H13A	0.9900
C3—C4	1.427 (2)	C13—H13B	0.9900
C3—C6	1.4992 (19)	C14—H14A	0.9800
C4—C5	1.502 (2)	C14—H14B	0.9800
C5—H5A	0.9800	C14—H14C	0.9800

O2—S1—O1	116.72 (7)	C11—C6—C3	118.12 (13)
O2—S1—N2	110.47 (7)	C7—C6—C3	123.68 (13)
O1—S1—N2	109.69 (7)	C8—C7—C6	119.76 (13)
O2—S1—N1	106.73 (7)	C8—C7—C12	118.63 (12)
O1—S1—N1	109.12 (7)	C6—C7—C12	121.60 (12)
N2—S1—N1	103.20 (6)	C9—C8—C7	120.93 (13)
C12—O4—C13	117.73 (11)	C9—C8—H8	119.5
C2—N1—S1	121.31 (10)	C7—C8—H8	119.5
C2—N1—H1	121.2 (12)	C8—C9—C10	119.44 (14)
S1—N1—H1	117.2 (12)	C8—C9—H9	120.3
C4—N2—S1	119.50 (11)	C10—C9—H9	120.3
C2—C1—H1A	109.5	C9—C10—C11	120.28 (14)
C2—C1—H1B	109.5	C9—C10—H10	119.9
H1A—C1—H1B	109.5	C11—C10—H10	119.9
C2—C1—H1C	109.5	C10—C11—C6	121.38 (14)
H1A—C1—H1C	109.5	C10—C11—H11	119.3
H1B—C1—H1C	109.5	C6—C11—H11	119.3
N1—C2—C3	120.21 (13)	O3—C12—O4	123.68 (12)
N1—C2—C1	114.38 (13)	O3—C12—C7	124.07 (13)
C3—C2—C1	125.23 (13)	O4—C12—C7	112.25 (11)
C2—C3—C4	119.86 (13)	O4—C13—C14	106.74 (11)
C2—C3—C6	121.10 (13)	O4—C13—H13A	110.4
C4—C3—C6	118.59 (13)	C14—C13—H13A	110.4
N2—C4—C3	124.64 (13)	O4—C13—H13B	110.4
N2—C4—C5	115.46 (14)	C14—C13—H13B	110.4
C3—C4—C5	119.84 (13)	H13A—C13—H13B	108.6
C4—C5—H5A	109.5	C13—C14—H14A	109.5
C4—C5—H5B	109.5	C13—C14—H14B	109.5
H5A—C5—H5B	109.5	H14A—C14—H14B	109.5
C4—C5—H5C	109.5	C13—C14—H14C	109.5
H5A—C5—H5C	109.5	H14A—C14—H14C	109.5
H5B—C5—H5C	109.5	H14B—C14—H14C	109.5
C11—C6—C7	118.20 (13)

O2—S1—N1—C2	151.55 (12)	C2—C3—C6—C7	74.6 (2)
O1—S1—N1—C2	−81.50 (13)	C4—C3—C6—C7	−97.68 (17)
N2—S1—N1—C2	35.09 (13)	C11—C6—C7—C8	−0.2 (2)
O2—S1—N2—C4	−146.56 (12)	C3—C6—C7—C8	179.14 (14)
O1—S1—N2—C4	83.40 (13)	C11—C6—C7—C12	179.72 (14)
N1—S1—N2—C4	−32.79 (13)	C3—C6—C7—C12	−0.9 (2)
S1—N1—C2—C3	−16.62 (19)	C6—C7—C8—C9	−0.9 (2)
S1—N1—C2—C1	167.96 (11)	C12—C7—C8—C9	179.14 (14)
N1—C2—C3—C4	−9.2 (2)	C7—C8—C9—C10	1.7 (2)
C1—C2—C3—C4	165.70 (14)	C8—C9—C10—C11	−1.2 (3)
N1—C2—C3—C6	178.59 (13)	C9—C10—C11—C6	0.1 (3)
C1—C2—C3—C6	−6.5 (2)	C7—C6—C11—C10	0.6 (2)
S1—N2—C4—C3	13.8 (2)	C3—C6—C11—C10	−178.75 (15)
S1—N2—C4—C5	−169.16 (12)	C13—O4—C12—O3	1.8 (2)
C2—C3—C4—N2	11.2 (2)	C13—O4—C12—C7	−177.25 (12)
C6—C3—C4—N2	−176.42 (14)	C8—C7—C12—O3	−150.10 (15)
C2—C3—C4—C5	−165.74 (14)	C6—C7—C12—O3	30.0 (2)
C6—C3—C4—C5	6.7 (2)	C8—C7—C12—O4	28.97 (19)
C2—C3—C6—C11	−106.03 (17)	C6—C7—C12—O4	−150.95 (13)
C4—C3—C6—C11	81.65 (18)	C12—O4—C13—C14	179.87 (12)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O3ⁱ	0.97 (2)	1.85 (2)	2.8157 (16)	175 (2)
C5—H5A···O1ⁱⁱ	0.98	2.52	3.310 (2)	137

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

Experimental details

Crystal data
Chemical formula	C₁₄H₁₆N₂O₄S
M_r	308.35
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	173
a, b, c (Å)	10.3943 (2), 6.6089 (2), 10.6563 (3)
β (°)	94.982 (2)
V (Å³)	729.27 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.24
Crystal size (mm)	0.25 × 0.24 × 0.23

Data collection
Diffractometer	Nonius KappaCCD
Absorption correction	Multi-scan (SADABS; Bruker, 2006)
T_min, T_max	0.943, 0.947
No. of measured, independent and observed [I > 2σ(I)] reflections	3321, 3321, 3083
R_int	0.013
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.067, 1.08
No. of reflections	3321
No. of parameters	198
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.22
Absolute structure	Flack (1983) ???? Friedel pairs
Absolute structure parameter	−0.03 (5)

Computer programs: COLLECT (Nonius, 2000), DENZO-SMN (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O3ⁱ	0.969 (16)	1.849 (16)	2.8157 (16)	174.6 (15)
C5—H5A···O1ⁱⁱ	0.98	2.52	3.310 (2)	137

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

Acknowledgements

The authors thank Dr Hong Su from the University of Cape Town for assistance with the data collection and refinement.

References

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