2-(2-Furyl­methyl)-1-methyl-3-oxo­cyclo­hexane­carboxyl­ic acid

The title compound, C₁₃H₁₆O₄, appears as an intermediate in the synthetic pathway of furosesquiterpenes. The crystal structure is dictated by the presence of intermolecular hydrogen bonding. It is noticeable that there are rather similar C-O distances in the carboxyl group [(1.2454(14) and 1.2835 (14) Å]. In the solid state, the mol­ecules interact in pairs, forming discrete dimers as part of a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.039
• wR factor = 0.113
• Data-to-parameter ratio = 18.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Marine sponges and different plants are rich sources of several furosesquiterpenes (Fraga, 1988, 1990). Linearly fused furo[2,3-b]- and furo[3,2-b]decalin systems with cis–trans ring junctions are present in compounds such as atractylon (Honan, 1985), furodysin (Vaillancourt et al., 1991), isoalantolactone (Tada et al., 1993), euryopsonal (Rivett & Wooland, 1967). As part of a program on the synthesis of furosesquiterpenes, racemic crystals of the intermediate product 2-(2-furylmethyl)-1-methyl-3-oxocyclohexanecarboxylic acid, (I), were obtained. The molecule of (I) is composed by a six- and a five-membered ring joined by a methylene group. The six-membered ring (C1–C6) (Fig. 1) adopts a chair conformation and the five-membered ring (C8–C11/O1) (Fig. 1) is planar (mean deviation = 0.0004 Å); the dihedral angle between the rings is 76.34 (5)°. The carboxyl group and the six-membered ring form an angle of 62,78 (6)°, whereas the angle is 39.76 (15)° between the carboxyl group and the five-membered ring.

Geometric parameters are mostly as expected (Table 1). The C7—C8—C9 [134.09 (13)°] and C1—C7—C8 [114.50 (10)°] angles are conditioned by the intramolecular environment, in particular by the intramolecular contacts C1···C8 = 2.542 (2) Å, C7···O4 = 2.779 (2) Å, and C7···O1 = 2.428 (2) Å. The relevant feature found in this monoclinic crystal is the existence of intermolecular hydrogen bonding. The carboxyl group serves as a simultaneous hydrogen-bond donor and acceptor. Although in compounds with a similar carboxyl-group environment to (I), single [1.320 (3) Å] and double [1.217 (3) Å] C═O bonds are clearly distinguished (Shi et al., 2002), it is noticeable that here both C—O bonds of the carboxyl group are rather similar [C12—O3 = 1.2835 (14) Å and C12—O2 = 1.2454 (14) Å], such influence of the hydrogen bonding on the C—OH and C═O distances of (I) has been described (Jeffrey & Saenger, 1994). The hydrogen bonding is shown in Fig. 2 and pertinent parameters are given in Table 2. As two hydrogen bonds take place between the same two molecules, discrete dimers are formed through a three-dimensional network (Fig. 3).

S2. Experimental

The title compound, (I), was synthesized in four steps starting from Hagemann's ester. Alkylation of Hagemann's ester with 2-furylmethyl chloride in the presence of t-BuOK as base afforded a C-3-alkylated product which, on alkaline hydrolytic decarboxylation, produced the furylmethylcyclohexenone derivative. The compound on treatment with KCN followed by hydrolysis afforded the title compound, (I), as a white solid (Chakraborty et al., 1997). Single crystals were grown with slow evaporation of an ethyl acetate solution of this compound.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. View of the title molecule, showing the atomic numbering and 50% probability displacement ellipsoids. H atoms have been omitted for clarity.
	Fig. 2. The intermolecular hydrogen bonding in (I). H atoms are shown as small spheres of arbitrary radii and hydrogen bonds are shown as dashed lines.
	Fig. 3. Packing diagram of the title compound, showing the existence of discrete dimers. The dashed lines denote the intermolecular hydrogen bonds.

2-(2-furylmethyl)-1-methyl-3-oxocyclohexanecarboxylic acid

Crystal data

C13H16O4	F(000) = 504
Mr = 236.26	Dx = 1.320 Mg m^−3
Monoclinic, P21/n	Melting point = 454–456 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 6.043 (1) Å	Cell parameters from 4362 reflections
b = 20.996 (1) Å	θ = 2.0–28.0°
c = 9.372 (1) Å	µ = 0.10 mm^−1
β = 91.912 (1)°	T = 298 K
V = 1188.5 (1) Å^3	Block, colourless
Z = 4	0.55 × 0.52 × 0.48 mm

Data collection

Bruker CCD area-detector diffractometer	2821 independent reflections
Radiation source: fine-focus sealed tube	2338 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ϕ and ω scans	θmax = 28.3°, θmin = 1.9°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −6→8
Tmin = 0.948, Tmax = 0.955	k = −27→27
7581 measured reflections	l = −11→12

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0561P)^2 + 0.229P] where P = (Fo^2 + 2Fc^2)/3
2821 reflections	(Δ/σ)max < 0.001
155 parameters	Δρmax = 0.25 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

Special details

Experimental. Data was collected using a Siemens SMART CCD based diffractometer operating at room temperature. Data was measured using omega scans of 0.3 degrees per frame for 60 s. A total of 1271 frames were collected. The first 50 frames were recollected at the end of each set of frames. As usual in organic compounds high theta reflections are too weak to be measured.

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	0.69708 (17)	0.05960 (5)	0.47329 (10)	0.0571 (3)
O2	0.88849 (15)	0.04812 (4)	0.87185 (10)	0.0512 (3)
O3	1.21512 (16)	0.05580 (5)	0.98806 (10)	0.0534 (3)
H3A	1.1694	0.0238	1.0277	0.064*
O4	1.08516 (18)	0.22327 (5)	0.50895 (10)	0.0578 (3)
C1	0.98815 (18)	0.14284 (5)	0.67712 (11)	0.0325 (2)
H1	0.8321	0.1351	0.6966	0.039*
C2	1.12213 (18)	0.13758 (5)	0.82115 (11)	0.0336 (2)
C3	1.0422 (2)	0.18961 (6)	0.92510 (12)	0.0410 (3)
H3B	0.8885	0.1817	0.9460	0.049*
H3C	1.1283	0.1867	1.0141	0.049*
C4	1.0632 (2)	0.25651 (6)	0.86525 (15)	0.0484 (3)
H4A	1.2179	0.2661	0.8510	0.058*
H4B	1.0071	0.2871	0.9327	0.058*
C5	0.9330 (2)	0.26195 (6)	0.72347 (15)	0.0482 (3)
H5A	0.7760	0.2572	0.7393	0.058*
H5B	0.9567	0.3036	0.6819	0.058*
C6	1.00756 (19)	0.21105 (6)	0.62301 (13)	0.0389 (3)
C7	1.0578 (2)	0.09369 (6)	0.56609 (13)	0.0430 (3)
H7A	1.1996	0.1064	0.5297	0.052*
H7B	1.0782	0.0529	0.6132	0.052*
C8	0.8975 (2)	0.08555 (6)	0.44349 (13)	0.0424 (3)
C9	0.9065 (3)	0.09571 (7)	0.30258 (14)	0.0553 (4)
H9	1.0249	0.1130	0.2549	0.066*
C10	0.7012 (3)	0.07513 (8)	0.23945 (16)	0.0612 (4)
H10	0.6595	0.0764	0.1431	0.073*
C11	0.5813 (3)	0.05386 (8)	0.34545 (17)	0.0629 (4)
H11	0.4389	0.0374	0.3347	0.075*
C12	1.06919 (18)	0.07530 (5)	0.89546 (12)	0.0354 (2)
C13	1.3722 (2)	0.14276 (7)	0.79924 (15)	0.0464 (3)
H13A	1.4484	0.1470	0.8902	0.070*
H13B	1.4015	0.1794	0.7416	0.070*
H13C	1.4228	0.1051	0.7522	0.070*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0555 (6)	0.0701 (7)	0.0459 (5)	−0.0057 (5)	0.0038 (4)	−0.0043 (5)
O2	0.0479 (5)	0.0490 (5)	0.0562 (6)	−0.0121 (4)	−0.0055 (4)	0.0171 (4)
O3	0.0554 (6)	0.0506 (5)	0.0533 (5)	−0.0065 (4)	−0.0121 (4)	0.0206 (4)
O4	0.0645 (6)	0.0600 (6)	0.0492 (5)	−0.0103 (5)	0.0072 (5)	0.0190 (4)
C1	0.0325 (5)	0.0325 (5)	0.0325 (5)	−0.0001 (4)	0.0025 (4)	0.0024 (4)
C2	0.0327 (5)	0.0335 (5)	0.0344 (5)	−0.0010 (4)	−0.0002 (4)	0.0037 (4)
C3	0.0461 (6)	0.0400 (6)	0.0368 (6)	−0.0003 (5)	−0.0021 (5)	−0.0028 (5)
C4	0.0543 (7)	0.0361 (6)	0.0543 (7)	−0.0019 (5)	−0.0065 (6)	−0.0054 (5)
C5	0.0542 (8)	0.0322 (6)	0.0577 (8)	0.0012 (5)	−0.0079 (6)	0.0043 (5)
C6	0.0356 (6)	0.0394 (6)	0.0415 (6)	−0.0039 (5)	−0.0043 (5)	0.0090 (5)
C7	0.0477 (7)	0.0429 (6)	0.0387 (6)	0.0082 (5)	0.0051 (5)	−0.0017 (5)
C8	0.0515 (7)	0.0370 (6)	0.0389 (6)	0.0053 (5)	0.0061 (5)	−0.0038 (5)
C9	0.0731 (9)	0.0550 (8)	0.0382 (7)	0.0009 (7)	0.0077 (6)	−0.0014 (6)
C10	0.0844 (11)	0.0558 (8)	0.0425 (7)	0.0140 (8)	−0.0110 (7)	−0.0108 (6)
C11	0.0608 (9)	0.0666 (10)	0.0604 (9)	0.0037 (7)	−0.0099 (7)	−0.0158 (7)
C12	0.0375 (6)	0.0353 (5)	0.0332 (5)	0.0007 (4)	0.0011 (4)	0.0030 (4)
C13	0.0339 (6)	0.0509 (7)	0.0543 (7)	−0.0023 (5)	−0.0007 (5)	0.0095 (6)

Geometric parameters (Å, º)

O1—C8	1.3657 (16)	C4—H4A	0.9700
O1—C11	1.3723 (17)	C4—H4B	0.9700
O2—C12	1.2454 (14)	C5—C6	1.5033 (18)
O3—C12	1.2835 (14)	C5—H5A	0.9700
O3—H3A	0.8200	C5—H5B	0.9700
O4—C6	1.2090 (15)	C7—C8	1.4877 (17)
C1—C6	1.5251 (15)	C7—H7A	0.9700
C1—C7	1.5344 (16)	C7—H7B	0.9700
C1—C2	1.5547 (15)	C8—C9	1.3405 (18)
C1—H1	0.9800	C9—C10	1.424 (2)
C2—C12	1.5206 (15)	C9—H9	0.9300
C2—C13	1.5355 (16)	C10—C11	1.326 (2)
C2—C3	1.5516 (16)	C10—H10	0.9300
C3—C4	1.5195 (18)	C11—H11	0.9300
C3—H3B	0.9700	C13—H13A	0.9600
C3—H3C	0.9700	C13—H13B	0.9600
C4—C5	1.5260 (18)	C13—H13C	0.9600
C8—O1—C11	106.63 (11)	H5A—C5—H5B	108.2
C12—O3—H3A	109.5	O4—C6—C5	122.43 (12)
C6—C1—C7	112.35 (9)	O4—C6—C1	121.98 (12)
C6—C1—C2	108.17 (9)	C5—C6—C1	115.55 (10)
C7—C1—C2	113.22 (9)	C8—C7—C1	114.50 (10)
C6—C1—H1	107.6	C6—C5—H5A	109.8
C7—C1—H1	107.6	C4—C5—H5A	109.8
C2—C1—H1	107.6	C6—C5—H5B	109.8
C12—C2—C13	110.19 (9)	C4—C5—H5B	109.8
C12—C2—C3	104.08 (9)	H5A—C5—H5B	108.2
C13—C2—C3	111.26 (10)	C9—C8—O1	109.29 (12)
C12—C2—C1	110.33 (9)	C9—C8—C7	134.09 (13)
C13—C2—C1	111.42 (9)	O1—C8—C7	116.55 (11)
C3—C2—C1	109.33 (9)	C8—C9—C10	107.32 (14)
C4—C3—C2	112.79 (10)	C8—C9—H9	126.3
C4—C3—H3B	109.0	C10—C9—H9	126.3
C2—C3—H3B	109.0	C11—C10—C9	106.33 (13)
C4—C3—H3C	109.0	C11—C10—H10	126.8
C2—C3—H3C	109.0	C9—C10—H10	126.8
H3B—C3—H3C	107.8	C10—C11—O1	110.43 (14)
C3—C4—C5	110.08 (10)	C10—C11—H11	124.8
C3—C4—H4A	109.6	O1—C11—H11	124.8
C5—C4—H4A	109.6	O2—C12—O3	123.55 (10)
C3—C4—H4B	109.6	O2—C12—C2	120.62 (10)
C5—C4—H4B	109.6	O3—C12—C2	115.70 (10)
H4A—C4—H4B	108.2	C2—C13—H13A	109.5
C6—C5—C4	109.59 (10)	C2—C13—H13B	109.5
C6—C5—H5A	109.8	H13A—C13—H13B	109.5
C4—C5—H5A	109.8	C2—C13—H13C	109.5
C6—C5—H5B	109.8	H13A—C13—H13C	109.5
C4—C5—H5B	109.8	H13B—C13—H13C	109.5
C6—C1—C2—C12	167.91 (9)	C6—C1—C7—C8	−72.62 (13)
C7—C1—C2—C12	−66.89 (12)	C2—C1—C7—C8	164.47 (10)
C6—C1—C2—C13	−69.36 (12)	C11—O1—C8—C9	0.09 (15)
C7—C1—C2—C13	55.83 (13)	C11—O1—C8—C7	−177.29 (11)
C6—C1—C2—C3	54.03 (12)	C1—C7—C8—C9	116.68 (16)
C7—C1—C2—C3	179.22 (9)	C1—C7—C8—O1	−66.77 (14)
C12—C2—C3—C4	−175.42 (10)	O1—C8—C9—C10	−0.03 (16)
C13—C2—C3—C4	65.94 (13)	C7—C8—C9—C10	176.70 (14)
C1—C2—C3—C4	−57.55 (13)	C8—C9—C10—C11	−0.04 (17)
C2—C3—C4—C5	57.55 (14)	C9—C10—C11—O1	0.09 (18)
C3—C4—C5—C6	−54.76 (15)	C8—O1—C11—C10	−0.11 (17)
C4—C5—C6—O4	−120.35 (13)	C13—C2—C12—O2	−149.21 (12)
C4—C5—C6—C1	57.14 (14)	C3—C2—C12—O2	91.41 (13)
C7—C1—C6—O4	−5.01 (16)	C1—C2—C12—O2	−25.77 (15)
C2—C1—C6—O4	120.70 (12)	C13—C2—C12—O3	34.89 (14)
C7—C1—C6—C5	177.49 (10)	C3—C2—C12—O3	−84.48 (12)
C2—C1—C6—C5	−56.80 (13)	C1—C2—C12—O3	158.34 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3A···O2^i	0.82	1.82	2.6327 (13)	171

Symmetry code: (i) −x+2, −y, −z+2.