Methyl 3-para-anisyl-4-(2-hydroxy­benzoyl)­isoxazole-5-carboxyl­ate

The title compound, C₁₉H₁₅NO₆, contains a planar isoxazole ring. An intramolecular hydrogen bond is formed between the OH group attached to a phenyl ring and a carbonyl O atom.

S1. Comment

In one of our research fields, the dipole–dipolarophile approach has been investigated. In the case of dipolar 1,3-cycloadditions, we have studied the reaction of diarylnitrilimines with dipolarophile derivatives of lindanone (Kerbal et al., 1988), titralone (Theobald et al., 1990) or lisochromanone (Kerbal et al., 1990). Recently, our research has been focused on the reaction of arylnitriloxides with isoquinoline arylidines (Badri et al., 1999). We are trying to extend this research to the behaviour of new heterocyclic dipolarophiles, particularly that of esters of 4-Oxo-4H-1-benzopyrancarboxylate with arylnitriloxides. However, the isoxazolinic cycloadducts obtained so far seem to transform to more stable isoxazole products due to the opening of the pyronic cycle. Since NMR spectroscopy did not provide sufficient information about the regiochemistry of the reaction product we have carried out the X-ray structure analysis of the title compound, (I). The isoxazole ring of the title compound is planar (r.m.s. deviation = 0.004 Å) with the methoxycarbonyl moiety coplanar to it. The phenyl ring at C3 encloses an angle of 35.55 (3)° with the isoxazole ring. The other phenyl ring is nearly perpendicular [77.44 (5)°] to the isoxazole ring. An intramolecular hydrogen bond is formed between the hydroxyl group attached to a phenyl ring and a carbonyl O atom, so that a new six-membered ring is formed. Furthermore, there is a short intermolecular contact between the ester carbonyl O atom (O51) and the hydroxyl group.

S2. Experimental

4-Oxo-4H-1-benzopyran-2-carboxylate (9.8 mmol, 2 g) methyl ester and hydroxycarbamoyl chloride (12 mmol) were mixed in anhydrous benzene (30 ml). The mixture was stirred, with regular addition of triethylamine (4 ml), for 15 min. After 2 h, the triethylamine chlorohydrate was eliminated and the solvent evaporated. The residue was then recrystallized from methanol.

S3. Refinement

All H atoms were initially located by difference Fourier synthesis. Subsequently, their positions were idealized and constrained to ride on their parent atoms with C—H(aromatic) = 0.95 or C—H(methyl) = 0.98 Å, and fixed individual displacement parameters [U(H) = 1.5U_eq(C_methyl) or U(H) = 1.2U_eq(C)]. The hydroxyl H atom was refined freely.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

Crystal data

C19H15NO6	F(000) = 736
Mr = 353.32	Dx = 1.443 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 11.172 (1) Å	Cell parameters from 8192 reflections
b = 9.337 (1) Å	θ = 1–25°
c = 15.634 (1) Å	µ = 0.11 mm^−1
β = 94.10 (1)°	T = 173 K
V = 1626.7 (2) Å^3	Block, light yellow
Z = 4	0.60 × 0.50 × 0.30 mm

Data collection

Siemens CCD three-circle diffractometer	4240 independent reflections
Radiation source: fine-focus sealed tube	3444 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.030
ω scans	θmax = 29.6°, θmin = 2.2°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −15→15
Tmin = 0.938, Tmax = 0.968	k = −12→12
32334 measured reflections	l = −21→21

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.105	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0507P)^2 + 0.677P] where P = (Fo^2 + 2Fc^2)/3
4240 reflections	(Δ/σ)max < 0.001
239 parameters	Δρmax = 0.62 e Å^−3
0 restraints	Δρmin = −0.24 e Å^−3

Special details

Experimental. The data collection nominally covered a sphere of reciprocal space, by a combination of seven sets of exposures; each set had a different ϕ angle for the crystal and each exposure covered 0.3° in ω. The crystal-to-detector distance was 4.5 cm. Coverage of the unique set is complete to at least 26.4° in θ. Crystal decay was monitored by repeating the initial frames at the end of data collection and analyzing the duplicate reflections.

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.11072 (8)	0.56803 (9)	0.46782 (5)	0.02328 (19)
N2	0.09198 (10)	0.46596 (11)	0.40241 (7)	0.0242 (2)
C3	0.13993 (10)	0.34628 (13)	0.43272 (8)	0.0200 (2)
C4	0.19088 (10)	0.36469 (13)	0.51856 (7)	0.0190 (2)
C5	0.16866 (10)	0.50341 (13)	0.53603 (7)	0.0197 (2)
C31	0.13220 (11)	0.21589 (13)	0.38037 (8)	0.0210 (2)
C32	0.11327 (11)	0.08298 (14)	0.41719 (8)	0.0242 (3)
H32	0.1120	0.0756	0.4777	0.029*
C33	0.09623 (12)	−0.03908 (14)	0.36723 (8)	0.0257 (3)
H33	0.0833	−0.1292	0.3932	0.031*
C34	0.09826 (11)	−0.02814 (14)	0.27864 (8)	0.0252 (3)
O34	0.08039 (10)	−0.13909 (10)	0.22331 (6)	0.0343 (2)
C341	0.05452 (15)	−0.27574 (16)	0.25924 (11)	0.0388 (4)
H34A	0.0440	−0.3469	0.2132	0.058*
H34B	−0.0193	−0.2692	0.2893	0.058*
H34C	0.1212	−0.3046	0.2997	0.058*
C35	0.11917 (13)	0.10421 (15)	0.24126 (9)	0.0297 (3)
H35	0.1220	0.1113	0.1808	0.036*
C36	0.13577 (12)	0.22469 (14)	0.29142 (8)	0.0264 (3)
H36	0.1498	0.3145	0.2653	0.032*
C41	0.25978 (10)	0.25752 (12)	0.57350 (7)	0.0190 (2)
O41	0.21027 (8)	0.19354 (10)	0.62963 (6)	0.0263 (2)
C42	0.38471 (10)	0.23101 (13)	0.55552 (8)	0.0200 (2)
C43	0.45438 (11)	0.13130 (13)	0.60461 (8)	0.0214 (2)
O43	0.41246 (9)	0.05940 (11)	0.67068 (6)	0.0296 (2)
H43	0.334 (2)	0.085 (2)	0.6720 (14)	0.061 (6)*
C44	0.57243 (12)	0.10453 (14)	0.58578 (8)	0.0258 (3)
H44	0.6198	0.0377	0.6192	0.031*
C45	0.62035 (12)	0.17488 (16)	0.51894 (9)	0.0312 (3)
H45	0.7009	0.1562	0.5065	0.037*
C46	0.55246 (13)	0.27316 (17)	0.46922 (9)	0.0344 (3)
H46	0.5862	0.3206	0.4229	0.041*
C47	0.43640 (12)	0.30104 (15)	0.48766 (9)	0.0283 (3)
H47	0.3903	0.3687	0.4540	0.034*
C51	0.19609 (10)	0.58840 (13)	0.61493 (8)	0.0206 (2)
O51	0.24608 (9)	0.53740 (10)	0.67821 (6)	0.0290 (2)
O52	0.16074 (8)	0.72334 (9)	0.60444 (6)	0.02342 (19)
C53	0.18341 (12)	0.81617 (14)	0.67821 (9)	0.0277 (3)
H53A	0.1538	0.9127	0.6641	0.042*
H53B	0.2699	0.8201	0.6938	0.042*
H52C	0.1419	0.7785	0.7266	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0286 (4)	0.0200 (4)	0.0206 (4)	0.0034 (3)	−0.0024 (3)	−0.0010 (3)
N2	0.0295 (5)	0.0216 (5)	0.0209 (5)	0.0022 (4)	−0.0018 (4)	−0.0025 (4)
C3	0.0192 (5)	0.0214 (6)	0.0196 (5)	0.0007 (4)	0.0020 (4)	0.0006 (4)
C4	0.0175 (5)	0.0208 (5)	0.0188 (5)	0.0002 (4)	0.0028 (4)	−0.0004 (4)
C5	0.0188 (5)	0.0207 (5)	0.0198 (5)	0.0008 (4)	0.0014 (4)	0.0014 (4)
C31	0.0198 (5)	0.0219 (6)	0.0210 (6)	0.0011 (4)	0.0002 (4)	−0.0021 (5)
C32	0.0280 (6)	0.0246 (6)	0.0198 (6)	0.0007 (5)	−0.0003 (5)	−0.0001 (5)
C33	0.0295 (6)	0.0209 (6)	0.0265 (6)	0.0002 (5)	0.0006 (5)	0.0000 (5)
C34	0.0253 (6)	0.0236 (6)	0.0264 (6)	0.0020 (5)	−0.0004 (5)	−0.0069 (5)
O34	0.0478 (6)	0.0251 (5)	0.0297 (5)	−0.0005 (4)	0.0005 (4)	−0.0098 (4)
C341	0.0454 (9)	0.0258 (7)	0.0460 (9)	−0.0072 (6)	0.0098 (7)	−0.0110 (6)
C35	0.0399 (7)	0.0291 (7)	0.0202 (6)	0.0011 (6)	0.0029 (5)	−0.0027 (5)
C36	0.0333 (7)	0.0232 (6)	0.0230 (6)	0.0000 (5)	0.0031 (5)	0.0012 (5)
C41	0.0219 (5)	0.0179 (5)	0.0171 (5)	−0.0002 (4)	0.0006 (4)	−0.0019 (4)
O41	0.0260 (5)	0.0287 (5)	0.0248 (4)	0.0021 (4)	0.0064 (4)	0.0074 (4)
C42	0.0205 (5)	0.0201 (5)	0.0195 (5)	0.0005 (4)	0.0014 (4)	0.0005 (4)
C43	0.0250 (6)	0.0202 (5)	0.0191 (5)	0.0012 (5)	0.0015 (4)	−0.0003 (4)
O43	0.0297 (5)	0.0307 (5)	0.0291 (5)	0.0070 (4)	0.0071 (4)	0.0129 (4)
C44	0.0248 (6)	0.0270 (6)	0.0255 (6)	0.0062 (5)	−0.0003 (5)	0.0016 (5)
C45	0.0220 (6)	0.0404 (8)	0.0316 (7)	0.0049 (5)	0.0054 (5)	0.0027 (6)
C46	0.0262 (7)	0.0466 (8)	0.0313 (7)	0.0015 (6)	0.0078 (5)	0.0133 (6)
C47	0.0255 (6)	0.0331 (7)	0.0266 (6)	0.0032 (5)	0.0031 (5)	0.0107 (5)
C51	0.0197 (5)	0.0201 (5)	0.0224 (6)	−0.0011 (4)	0.0034 (4)	−0.0003 (4)
O51	0.0374 (5)	0.0269 (5)	0.0218 (4)	0.0035 (4)	−0.0037 (4)	0.0000 (4)
O52	0.0278 (4)	0.0188 (4)	0.0233 (4)	0.0009 (3)	−0.0004 (3)	−0.0030 (3)
C53	0.0318 (7)	0.0232 (6)	0.0280 (6)	−0.0008 (5)	0.0013 (5)	−0.0075 (5)

Geometric parameters (Å, º)

O1—C5	1.3497 (14)	O34—C341	1.4319 (18)
O1—N2	1.4025 (13)	C35—C36	1.3762 (19)
N2—C3	1.3130 (16)	C41—O41	1.2257 (15)
C3—C4	1.4301 (16)	C41—C42	1.4644 (16)
C3—C31	1.4661 (17)	C42—C47	1.4050 (17)
C4—C5	1.3504 (17)	C42—C43	1.4057 (17)
C4—C41	1.4957 (16)	C43—O43	1.3440 (15)
C5—C51	1.4803 (17)	C43—C44	1.3943 (18)
C31—C32	1.3905 (18)	C44—C45	1.3748 (19)
C31—C36	1.3965 (17)	C45—C46	1.392 (2)
C32—C33	1.3871 (18)	C46—C47	1.3732 (19)
C33—C34	1.3906 (18)	C51—O51	1.1992 (15)
C34—O34	1.3552 (15)	C51—O52	1.3271 (15)
C34—C35	1.3938 (19)	O52—C53	1.4504 (15)
C5—O1—N2	108.08 (9)	C36—C35—C34	120.37 (12)
C3—N2—O1	106.23 (9)	C35—C36—C31	120.47 (12)
N2—C3—C4	111.16 (10)	O41—C41—C42	122.69 (11)
N2—C3—C31	119.93 (11)	O41—C41—C4	119.81 (11)
C4—C3—C31	128.86 (11)	C42—C41—C4	117.48 (10)
C5—C4—C3	103.80 (10)	C47—C42—C43	118.62 (11)
C5—C4—C41	128.32 (11)	C47—C42—C41	121.00 (11)
C3—C4—C41	127.76 (11)	C43—C42—C41	120.35 (11)
O1—C5—C4	110.71 (10)	O43—C43—C44	117.36 (11)
O1—C5—C51	118.54 (10)	O43—C43—C42	122.73 (11)
C4—C5—C51	130.74 (11)	C44—C43—C42	119.91 (11)
C32—C31—C36	118.74 (11)	C45—C44—C43	120.03 (12)
C32—C31—C3	120.97 (11)	C44—C45—C46	120.88 (12)
C36—C31—C3	120.16 (11)	C47—C46—C45	119.52 (13)
C33—C32—C31	121.25 (11)	C46—C47—C42	121.03 (12)
C32—C33—C34	119.29 (12)	O51—C51—O52	126.57 (11)
O34—C34—C33	124.58 (12)	O51—C51—C5	122.07 (11)
O34—C34—C35	115.57 (12)	O52—C51—C5	111.34 (10)
C33—C34—C35	119.86 (12)	C51—O52—C53	115.82 (10)
C34—O34—C341	117.09 (11)
C5—O1—N2—C3	−0.82 (13)	C32—C31—C36—C35	0.9 (2)
O1—N2—C3—C4	0.35 (13)	C3—C31—C36—C35	−174.90 (12)
O1—N2—C3—C31	178.10 (10)	C5—C4—C41—O41	82.87 (16)
N2—C3—C4—C5	0.24 (13)	C3—C4—C41—O41	−101.70 (15)
C31—C3—C4—C5	−177.26 (12)	C5—C4—C41—C42	−98.80 (15)
N2—C3—C4—C41	−176.07 (11)	C3—C4—C41—C42	76.63 (15)
C31—C3—C4—C41	6.4 (2)	O41—C41—C42—C47	176.60 (12)
N2—O1—C5—C4	1.01 (13)	C4—C41—C42—C47	−1.68 (17)
N2—O1—C5—C51	−178.34 (10)	O41—C41—C42—C43	−1.54 (18)
C3—C4—C5—O1	−0.77 (13)	C4—C41—C42—C43	−179.82 (11)
C41—C4—C5—O1	175.51 (11)	C47—C42—C43—O43	179.95 (12)
C3—C4—C5—C51	178.48 (12)	C41—C42—C43—O43	−1.87 (18)
C41—C4—C5—C51	−5.2 (2)	C47—C42—C43—C44	0.42 (18)
N2—C3—C31—C32	−141.56 (13)	C41—C42—C43—C44	178.60 (11)
C4—C3—C31—C32	35.75 (19)	O43—C43—C44—C45	−179.98 (12)
N2—C3—C31—C36	34.14 (18)	C42—C43—C44—C45	−0.4 (2)
C4—C3—C31—C36	−148.55 (13)	C43—C44—C45—C46	−0.1 (2)
C36—C31—C32—C33	−1.01 (19)	C44—C45—C46—C47	0.5 (2)
C3—C31—C32—C33	174.75 (12)	C45—C46—C47—C42	−0.5 (2)
C31—C32—C33—C34	0.1 (2)	C43—C42—C47—C46	0.1 (2)
C32—C33—C34—O34	−178.63 (12)	C41—C42—C47—C46	−178.11 (13)
C32—C33—C34—C35	1.0 (2)	O1—C5—C51—O51	179.12 (11)
C33—C34—O34—C341	1.76 (19)	C4—C5—C51—O51	−0.1 (2)
C35—C34—O34—C341	−177.90 (13)	O1—C5—C51—O52	−2.12 (15)
O34—C34—C35—C36	178.54 (12)	C4—C5—C51—O52	178.68 (12)
C33—C34—C35—C36	−1.1 (2)	O51—C51—O52—C53	−1.35 (18)
C34—C35—C36—C31	0.2 (2)	C5—C51—O52—C53	179.96 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O43—H43···O51^i	0.91 (2)	2.61 (2)	3.0593 (14)	111.7 (16)
O43—H43···O41	0.91 (2)	1.80 (2)	2.6221 (13)	149 (2)

Symmetry code: (i) −x+1/2, y−1/2, −z+3/2.