Dimethyl 5-acetyl-1-hy-droxy-4-methyl-1H-pyrrole-2,3-di-carboxyl-ate, an oxidation-resistant N-hy-droxy-pyrrole.

The title compound, C11H13NO6, exhibits an intra-molecular O-H⋯O=C hydrogen bond between the N-hydroxyl H atom and carbonyl O atom of the neighboring acetyl group. This finding contradicts a previously published model in which the hydrogen bond was postulated to occur with the neighboring carbomethoxy group. This relatively strong hydrogen bond [O-H⋯O: D = 2.5583 (11) Å and θ = 152°] may underlie the resistance of the title compound to oxidation into the corresponding nitroxide.

Related literature

The title compound was obtained as part of an effort to synthesize aromatic nitroxides and was prepared by a published procedure (Hekmatshoar et al., 2008 ▶). The compound could not be converted to the corresponding nitroxide under commonly used oxidation conditions (Keana et al., 1988 ▶). For analysis of intra­molecular hydrogen-bond parameters in organic crystals, see: Bilton et al. (2000 ▶); Galek et al. (2010 ▶). A survey of the effect of intra­molecular hydrogen bonding on the reduction potential of quinones appears in the review by Guin et al. (2011 ▶). Examples of hydrogen bonding affecting the redox properties of quinones are discussed by Gupta & Linschitz (1997 ▶) and Feldman et al. (2007 ▶).

Experimental

Crystal data

C11H13NO6

M = 255.22

Monoclinic,

a = 10.3893 (8) Å

b = 15.1803 (12) Å

c = 7.5789 (6) Å

β = 99.630 (1)°

V = 1178.45 (16) Å3

Z = 4

Mo Kα radiation

μ = 0.12 mm−1

T = 150 K

0.52 × 0.43 × 0.31 mm

Data collection

Bruker SMART APEXII diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T min = 0.888, T max = 0.964

19259 measured reflections

3437 independent reflections

2836 reflections with I > 2σ(I)

R int = 0.014

Refinement

R[F 2 > 2σ(F 2)] = 0.031

wR(F 2) = 0.064

S = 1.00

3437 reflections

215 parameters

All H-atom parameters refined

Δρmax = 0.35 e Å−3

Δρmin = −0.19 e Å−3

Data collection: APEX2 (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2010 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008 ▶); molecular graphics: XSHELL (Bruker, 2010 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536813034466/ld2115sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813034466/ld2115Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S1600536813034466/ld2115Isup3.cml

CCDC reference:

Additional supporting information: crystallographic information; 3D view; checkCIF report

C11H13NO6	F(000) = 536
Mr = 255.22	Dx = 1.439 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 13127 reflections
a = 10.3893 (8) Å	θ = 2.4–31.0°
b = 15.1803 (12) Å	µ = 0.12 mm−1
c = 7.5789 (6) Å	T = 150 K
β = 99.630 (1)°	Prism, colourless
V = 1178.45 (16) Å3	0.52 × 0.43 × 0.31 mm
Z = 4

Bruker SMART APEXII diffractometer	3437 independent reflections
Radiation source: fine-focus sealed tube	2836 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.014
Detector resolution: 8.333 pixels mm-1	θmax = 30.0°, θmin = 2.0°
φ and ω scans	h = −14→14
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −21→21
Tmin = 0.888, Tmax = 0.964	l = −10→10
19259 measured reflections

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)] = 0.031	Hydrogen site location: difference Fourier map
wR(F2) = 0.064	All H-atom parameters refined
S = 1.00	w = 1/[σ2(Fo2) + (0.01P)2 + 0.4962P], P = (max(Fo2,0) + 2Fc2)/3
3437 reflections	(Δ/σ)max < 0.001
215 parameters	Δρmax = 0.35 e Å−3
0 restraints	Δρmin = −0.19 e Å−3

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. For all H atoms both coordinate and isotropic displacement parameters were freely refined.All H atoms were located from the difference Fourier maps and refined unconstrained including isotropic displacement parameters.

	x	y	z	Uiso*/Ueq
N1	0.58967 (7)	0.15991 (5)	0.01532 (11)	0.02245 (15)
C1	0.57608 (9)	0.25121 (6)	0.00825 (12)	0.02170 (17)
C2	0.69238 (9)	0.28546 (6)	0.10473 (12)	0.02101 (16)
C3	0.77256 (8)	0.21282 (6)	0.16540 (12)	0.02102 (16)
C4	0.70478 (8)	0.13542 (6)	0.10655 (12)	0.02093 (17)
O1	0.49892 (7)	0.09969 (5)	−0.06513 (11)	0.03059 (16)
H1	0.4367 (15)	0.1346 (10)	−0.121 (2)	0.055 (4)*
C5	0.45803 (9)	0.28874 (6)	−0.09308 (13)	0.02522 (18)
O5	0.37225 (7)	0.23953 (5)	−0.17286 (11)	0.03488 (18)
C6	0.44010 (11)	0.38675 (7)	−0.10178 (16)	0.0318 (2)
H61	0.3632 (15)	0.3989 (10)	−0.190 (2)	0.056 (4)*
H62	0.4261 (14)	0.4098 (10)	0.012 (2)	0.048 (4)*
H63	0.5176 (13)	0.4162 (9)	−0.1332 (17)	0.039 (4)*
C7	0.72552 (11)	0.38090 (6)	0.13774 (14)	0.02725 (19)
H71	0.8031 (14)	0.3861 (10)	0.227 (2)	0.050 (4)*
H72	0.6559 (14)	0.4127 (9)	0.1794 (18)	0.044 (4)*
H73	0.7376 (13)	0.4103 (9)	0.0300 (19)	0.044 (4)*
C8	0.90325 (9)	0.21540 (6)	0.27407 (13)	0.02425 (18)
O8	0.96516 (8)	0.28077 (5)	0.32002 (13)	0.0425 (2)
O9	0.94825 (7)	0.13382 (5)	0.31885 (10)	0.02999 (16)
C9	1.07658 (11)	0.13084 (9)	0.42886 (18)	0.0394 (3)
H91	1.0973 (16)	0.0679 (11)	0.439 (2)	0.062 (5)*
H92	1.1394 (14)	0.1618 (10)	0.3656 (19)	0.046 (4)*
H93	1.0726 (13)	0.1588 (10)	0.543 (2)	0.046 (4)*
C10	0.74086 (8)	0.04013 (6)	0.13628 (12)	0.02129 (17)
O10	0.70851 (7)	−0.00387 (4)	0.25304 (10)	0.02722 (15)
O11	0.81287 (7)	0.01306 (5)	0.01819 (10)	0.02943 (16)
C11	0.86684 (14)	−0.07523 (8)	0.04835 (18)	0.0383 (3)
H111	0.9238 (14)	−0.0816 (9)	−0.0377 (19)	0.046 (4)*
H112	0.9172 (15)	−0.0775 (11)	0.170 (2)	0.060 (5)*
H113	0.7977 (15)	−0.1177 (11)	0.037 (2)	0.059 (5)*

	U11	U22	U33	U12	U13	U23
N1	0.0195 (3)	0.0176 (3)	0.0295 (4)	−0.0019 (3)	0.0019 (3)	−0.0014 (3)
C1	0.0216 (4)	0.0181 (4)	0.0260 (4)	0.0008 (3)	0.0056 (3)	0.0002 (3)
C2	0.0233 (4)	0.0185 (4)	0.0220 (4)	−0.0006 (3)	0.0061 (3)	−0.0007 (3)
C3	0.0203 (4)	0.0196 (4)	0.0232 (4)	−0.0016 (3)	0.0038 (3)	−0.0009 (3)
C4	0.0192 (4)	0.0186 (4)	0.0250 (4)	−0.0002 (3)	0.0040 (3)	−0.0004 (3)
O1	0.0225 (3)	0.0219 (3)	0.0438 (4)	−0.0053 (3)	−0.0046 (3)	−0.0031 (3)
C5	0.0224 (4)	0.0257 (4)	0.0284 (4)	0.0036 (3)	0.0068 (3)	0.0028 (4)
O5	0.0246 (3)	0.0322 (4)	0.0446 (4)	0.0018 (3)	−0.0036 (3)	0.0005 (3)
C6	0.0282 (5)	0.0256 (5)	0.0414 (6)	0.0066 (4)	0.0055 (4)	0.0056 (4)
C7	0.0338 (5)	0.0184 (4)	0.0291 (5)	−0.0026 (4)	0.0039 (4)	−0.0019 (4)
C8	0.0223 (4)	0.0251 (4)	0.0253 (4)	−0.0020 (3)	0.0037 (3)	0.0002 (3)
O8	0.0323 (4)	0.0298 (4)	0.0591 (5)	−0.0082 (3)	−0.0103 (4)	−0.0025 (4)
O9	0.0226 (3)	0.0286 (4)	0.0362 (4)	0.0011 (3)	−0.0027 (3)	0.0030 (3)
C9	0.0268 (5)	0.0473 (7)	0.0399 (6)	0.0063 (5)	−0.0063 (4)	0.0017 (5)
C10	0.0193 (4)	0.0186 (4)	0.0247 (4)	−0.0003 (3)	0.0001 (3)	−0.0014 (3)
O10	0.0305 (3)	0.0218 (3)	0.0303 (3)	−0.0020 (3)	0.0079 (3)	0.0013 (3)
O11	0.0368 (4)	0.0229 (3)	0.0308 (4)	0.0106 (3)	0.0120 (3)	0.0057 (3)
C11	0.0488 (7)	0.0259 (5)	0.0442 (6)	0.0169 (5)	0.0190 (6)	0.0075 (5)

N1—C4	1.3304 (11)	C7—H71	0.963 (15)
N1—O1	1.3799 (10)	C7—H72	0.965 (14)
N1—C1	1.3932 (11)	C7—H73	0.957 (14)
C1—C2	1.4033 (12)	C8—O8	1.2020 (12)
C1—C5	1.4503 (13)	C8—O9	1.3470 (12)
C2—C3	1.4118 (12)	O9—C9	1.4501 (13)
C2—C7	1.5005 (13)	C9—H91	0.980 (17)
C3—C4	1.4037 (12)	C9—H92	0.991 (15)
C3—C8	1.4661 (12)	C9—H93	0.971 (15)
C4—C10	1.5018 (12)	C10—O10	1.2007 (11)
O1—H1	0.888 (16)	C10—O11	1.3242 (11)
C5—O5	1.2399 (12)	O11—C11	1.4561 (12)
C5—C6	1.4995 (14)	C11—H111	0.956 (14)
C6—H61	0.968 (15)	C11—H112	0.981 (16)
C6—H62	0.963 (15)	C11—H113	0.958 (16)
C6—H63	0.985 (14)
C4—N1—O1	122.20 (8)	C2—C7—H72	112.0 (8)
C4—N1—C1	111.99 (7)	H71—C7—H72	108.4 (11)
O1—N1—C1	125.78 (8)	C2—C7—H73	111.6 (8)
N1—C1—C2	106.00 (8)	H71—C7—H73	110.1 (12)
N1—C1—C5	118.84 (8)	H72—C7—H73	104.9 (11)
C2—C1—C5	135.11 (8)	O8—C8—O9	122.66 (9)
C1—C2—C3	106.86 (8)	O8—C8—C3	125.82 (9)
C1—C2—C7	126.74 (8)	O9—C8—C3	111.52 (8)
C3—C2—C7	126.40 (8)	C8—O9—C9	114.87 (8)
C4—C3—C2	108.24 (8)	O9—C9—H91	104.2 (10)
C4—C3—C8	124.69 (8)	O9—C9—H92	108.9 (8)
C2—C3—C8	127.06 (8)	H91—C9—H92	110.4 (12)
N1—C4—C3	106.90 (8)	O9—C9—H93	109.0 (8)
N1—C4—C10	121.82 (8)	H91—C9—H93	113.3 (13)
C3—C4—C10	131.24 (8)	H92—C9—H93	110.7 (12)
N1—O1—H1	101.8 (10)	O10—C10—O11	125.81 (8)
O5—C5—C1	119.78 (9)	O10—C10—C4	123.55 (8)
O5—C5—C6	120.16 (9)	O11—C10—C4	110.64 (8)
C1—C5—C6	120.06 (9)	C10—O11—C11	115.20 (8)
C5—C6—H61	107.5 (9)	O11—C11—H111	104.6 (9)
C5—C6—H62	111.0 (9)	O11—C11—H112	108.1 (10)
H61—C6—H62	108.4 (12)	H111—C11—H112	110.1 (12)
C5—C6—H63	111.2 (8)	O11—C11—H113	110.0 (9)
H61—C6—H63	111.1 (11)	H111—C11—H113	114.3 (13)
H62—C6—H63	107.6 (11)	H112—C11—H113	109.5 (13)
C2—C7—H71	109.7 (9)
C4—N1—C1—C2	−0.55 (11)	C2—C3—C4—C10	−177.93 (9)
O1—N1—C1—C2	−178.69 (8)	C8—C3—C4—C10	1.01 (15)
C4—N1—C1—C5	177.39 (8)	N1—C1—C5—O5	−0.77 (14)
O1—N1—C1—C5	−0.75 (14)	C2—C1—C5—O5	176.43 (10)
N1—C1—C2—C3	0.48 (10)	N1—C1—C5—C6	179.45 (9)
C5—C1—C2—C3	−176.97 (10)	C2—C1—C5—C6	−3.36 (16)
N1—C1—C2—C7	−179.43 (9)	C4—C3—C8—O8	176.89 (10)
C5—C1—C2—C7	3.13 (17)	C2—C3—C8—O8	−4.37 (16)
C1—C2—C3—C4	−0.26 (10)	C4—C3—C8—O9	−3.19 (13)
C7—C2—C3—C4	179.64 (9)	C2—C3—C8—O9	175.56 (9)
C1—C2—C3—C8	−179.17 (9)	O8—C8—O9—C9	0.77 (15)
C7—C2—C3—C8	0.73 (15)	C3—C8—O9—C9	−179.15 (9)
O1—N1—C4—C3	178.61 (8)	N1—C4—C10—O10	−82.60 (12)
C1—N1—C4—C3	0.39 (11)	C3—C4—C10—O10	94.99 (12)
O1—N1—C4—C10	−3.29 (14)	N1—C4—C10—O11	97.95 (10)
C1—N1—C4—C10	178.50 (8)	C3—C4—C10—O11	−84.45 (12)
C2—C3—C4—N1	−0.07 (10)	O10—C10—O11—C11	−6.69 (15)
C8—C3—C4—N1	178.87 (8)	C4—C10—O11—C11	172.74 (9)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O5	0.888 (16)	1.746 (16)	2.5583 (11)	150.8 (14)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O5	0.888 (16)	1.746 (16)	2.5583 (11)	150.8 (14)