rac-(3E,3aR,6aR)-3-(Hydroxy­methyl­ene)-3,3a,6,6a-tetra­hydro-2H-cyclo­penta­[b]furan-2-one

The crystal structure of the title compound, C₈H₈O₃, was determined in the course of our studies of the synthesis of cyclo­penta­[1,2-b]furan-4-one derivatives. The title compound has two chiral C atoms and was obtained as a racemic mixture. It was found to possess a vinylogous acid group with an E configuration at the double bond. The compound exists in the hydroxy­methyl­ene and not in the tautomeric carbaldehyde form. The asymmetric unit consists of two molecules.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.056
• wR factor = 0.175
• Data-to-parameter ratio = 12.9

checkCIF/PLATON results

No syntax errors found



Alert level B
ABSTM02_ALERT_3_B  The ratio of Tmax/Tmin expected RT(exp) is > 1.20
            Absorption corrections should be applied.
            Tmin and Tmax expected:      0.698     0.844
            RT(exp) =      1.208
PLAT057_ALERT_3_B Correction for Absorption Required   RT(exp) ...       1.21

Alert level C
PLAT031_ALERT_4_C Refined Extinction Parameter within Range ......       3.25 Sigma
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          2
              C8 H8 O3

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CORINC (Dräger & Gattow, 1971); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPPIII (Johnson, 1976) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

(IV)

Crystal data

C8H8O3	F(000) = 640
Mr = 152.15	Dx = 1.381 Mg m^−3
Monoclinic, P21/c	Melting point: 119.3 K
Hall symbol: -P 2ybc	Cu Kα radiation, λ = 1.54178 Å
a = 11.9618 (2) Å	Cell parameters from 25 reflections
b = 8.5709 (8) Å	θ = 61–69°
c = 16.127 (3) Å	µ = 0.90 mm^−1
β = 117.741 (7)°	T = 295 K
V = 1463.3 (3) Å^3	Block, colourless
Z = 8	0.51 × 0.38 × 0.19 mm

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.014
Radiation source: rotating anode	θmax = 70.0°, θmin = 4.2°
Graphite monochromator	h = 0→14
ω/2θ scans	k = −10→0
2909 measured reflections	l = −19→17
2770 independent reflections	3 standard reflections every 60 min
2009 reflections with I > 2σ(I)	intensity decay: 5%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.056	H-atom parameters constrained
wR(F^2) = 0.175	w = 1/[σ^2(Fo^2) + (0.1021P)^2 + 0.2685P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
2770 reflections	Δρmax = 0.23 e Å^−3
214 parameters	Δρmin = −0.31 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0013 (4)

Special details

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	−0.07464 (14)	0.7396 (2)	0.34283 (12)	0.0598 (5)
C2	−0.0624 (2)	0.5923 (3)	0.30149 (18)	0.0588 (6)
H2A	−0.1142	0.5926	0.2332	0.065 (7)*
C3	−0.0968 (3)	0.4567 (3)	0.3457 (2)	0.0702 (8)
H3A	−0.1371	0.4934	0.3822	0.092 (7)*
H3B	−0.1531	0.3847	0.2983	0.092 (7)*
C4	0.0270 (3)	0.3809 (3)	0.4073 (2)	0.0770 (8)
H4	0.0365	0.2981	0.4474	0.111 (12)*
C5	0.1213 (3)	0.4448 (3)	0.3982 (2)	0.0734 (8)
H5	0.2047	0.4114	0.4309	0.102 (11)*
C6	0.0794 (2)	0.5765 (3)	0.32960 (18)	0.0578 (6)
H6A	0.0927	0.5531	0.2754	0.069 (8)*
C7	0.13048 (19)	0.7335 (3)	0.36986 (15)	0.0463 (5)
C8	0.03336 (19)	0.8215 (3)	0.37795 (15)	0.0462 (5)
C9	0.24574 (19)	0.7904 (3)	0.39531 (15)	0.0464 (5)
H9A	0.2710	0.8953	0.4306	0.066 (7)*
O10	0.33174 (15)	0.70527 (19)	0.38572 (13)	0.0596 (5)
H10	0.4045	0.7663	0.4095	0.095 (10)*
O11	0.03732 (14)	0.9515 (2)	0.41061 (12)	0.0591 (5)
O21	0.42176 (14)	1.0385 (2)	0.34635 (13)	0.0609 (5)
C22	0.4225 (2)	1.1807 (3)	0.29666 (17)	0.0562 (6)
H22A	0.3626	1.1732	0.2298	0.069 (8)*
C23	0.3941 (2)	1.3221 (3)	0.3410 (2)	0.0669 (7)
H23A	0.3279	1.3856	0.2939	0.085 (7)*
H23B	0.3685	1.2904	0.3874	0.085 (7)*
C24	0.5159 (3)	1.4082 (3)	0.3853 (2)	0.0664 (7)
H24	0.5284	1.4988	0.4203	0.094 (11)*
C25	0.6038 (2)	1.3438 (3)	0.37019 (19)	0.0619 (7)
H25	0.6851	1.3837	0.3931	0.099 (11)*
C26	0.55963 (19)	1.1990 (3)	0.31217 (16)	0.0500 (6)
H26A	0.5631	1.2090	0.2529	0.069 (8)*
C27	0.62224 (19)	1.0524 (3)	0.36345 (15)	0.0453 (5)
C28	0.53447 (19)	0.9661 (3)	0.38379 (16)	0.0492 (5)
C29	0.73959 (19)	1.0034 (3)	0.38919 (15)	0.0464 (5)
H29A	0.7750	0.9049	0.4311	0.055 (7)*
O30	0.81739 (14)	1.0853 (2)	0.36833 (12)	0.0580 (5)
H30	0.8988	1.0420	0.4013	0.120 (13)*
O31	0.54867 (16)	0.8444 (2)	0.42694 (13)	0.0629 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0387 (8)	0.0625 (10)	0.0813 (11)	−0.0055 (7)	0.0307 (8)	−0.0087 (9)
C2	0.0500 (13)	0.0655 (15)	0.0642 (15)	−0.0143 (11)	0.0293 (12)	−0.0134 (12)
C3	0.0625 (15)	0.0702 (17)	0.0875 (19)	−0.0240 (13)	0.0429 (15)	−0.0149 (15)
C4	0.0798 (19)	0.0533 (15)	0.106 (2)	−0.0143 (14)	0.0497 (18)	−0.0005 (16)
C5	0.0634 (16)	0.0487 (14)	0.114 (2)	−0.0009 (12)	0.0465 (16)	−0.0050 (15)
C6	0.0551 (13)	0.0607 (15)	0.0741 (15)	−0.0130 (11)	0.0439 (12)	−0.0160 (12)
C7	0.0431 (11)	0.0472 (12)	0.0567 (12)	−0.0026 (9)	0.0302 (10)	−0.0020 (10)
C8	0.0381 (10)	0.0500 (12)	0.0538 (12)	0.0000 (9)	0.0241 (9)	0.0019 (9)
C9	0.0414 (11)	0.0475 (12)	0.0591 (12)	0.0018 (9)	0.0309 (10)	0.0031 (10)
O10	0.0494 (9)	0.0531 (10)	0.0932 (12)	−0.0008 (7)	0.0474 (9)	−0.0020 (8)
O11	0.0446 (8)	0.0537 (10)	0.0823 (11)	0.0040 (7)	0.0324 (8)	−0.0051 (8)
O21	0.0386 (8)	0.0629 (10)	0.0879 (12)	0.0003 (7)	0.0349 (8)	0.0077 (9)
C22	0.0388 (11)	0.0672 (16)	0.0630 (14)	0.0051 (11)	0.0240 (11)	0.0074 (12)
C23	0.0555 (14)	0.0736 (18)	0.0831 (17)	0.0250 (13)	0.0419 (14)	0.0173 (14)
C24	0.0676 (16)	0.0517 (14)	0.0799 (18)	0.0138 (12)	0.0343 (14)	0.0036 (13)
C25	0.0513 (13)	0.0476 (13)	0.0890 (18)	0.0036 (11)	0.0346 (13)	0.0066 (12)
C26	0.0421 (11)	0.0557 (13)	0.0598 (13)	0.0073 (10)	0.0301 (10)	0.0085 (10)
C27	0.0393 (11)	0.0461 (12)	0.0561 (12)	0.0001 (9)	0.0268 (9)	−0.0014 (9)
C28	0.0398 (11)	0.0500 (12)	0.0616 (13)	−0.0028 (9)	0.0267 (10)	−0.0031 (11)
C29	0.0405 (10)	0.0429 (11)	0.0602 (13)	−0.0020 (9)	0.0270 (10)	−0.0023 (9)
O30	0.0407 (8)	0.0563 (10)	0.0864 (12)	0.0040 (7)	0.0374 (8)	0.0085 (8)
O31	0.0517 (9)	0.0550 (10)	0.0883 (12)	−0.0037 (8)	0.0379 (9)	0.0093 (9)

Geometric parameters (Å, º)

O1—C8	1.342 (3)	O21—C28	1.345 (3)
O1—C2	1.467 (3)	O21—C22	1.461 (3)
C2—C3	1.517 (4)	C22—C23	1.523 (4)
C2—C6	1.545 (3)	C22—C26	1.548 (3)
C2—H2A	0.9800	C22—H22A	0.9800
C3—C4	1.494 (4)	C23—C24	1.486 (4)
C3—H3A	0.9700	C23—H23A	0.9700
C3—H3B	0.9700	C23—H23B	0.9700
C4—C5	1.323 (4)	C24—C25	1.307 (4)
C4—H4	0.9300	C24—H24	0.9300
C5—C6	1.494 (4)	C25—C26	1.495 (3)
C5—H5	0.9300	C25—H25	0.9300
C6—C7	1.496 (3)	C26—C27	1.499 (3)
C6—H6A	0.9800	C26—H26A	0.9800
C7—C9	1.334 (3)	C27—C29	1.333 (3)
C7—C8	1.441 (3)	C27—C28	1.442 (3)
C8—O11	1.224 (3)	C28—O31	1.221 (3)
C9—O10	1.328 (2)	C29—O30	1.328 (2)
C9—H9A	1.0312	C29—H29A	1.0400
O10—H10	0.9318	O30—H30	0.9419
C8—O1—C2	111.22 (17)	C28—O21—C22	111.75 (16)
O1—C2—C3	109.82 (19)	O21—C22—C23	110.32 (19)
O1—C2—C6	105.67 (18)	O21—C22—C26	105.79 (17)
C3—C2—C6	107.2 (2)	C23—C22—C26	107.1 (2)
O1—C2—H2A	111.3	O21—C22—H22A	111.1
C3—C2—H2A	111.3	C23—C22—H22A	111.1
C6—C2—H2A	111.3	C26—C22—H22A	111.1
C4—C3—C2	104.2 (2)	C24—C23—C22	103.79 (19)
C4—C3—H3A	110.9	C24—C23—H23A	111.0
C2—C3—H3A	110.9	C22—C23—H23A	111.0
C4—C3—H3B	110.9	C24—C23—H23B	111.0
C2—C3—H3B	110.9	C22—C23—H23B	111.0
H3A—C3—H3B	108.9	H23A—C23—H23B	109.0
C5—C4—C3	112.3 (3)	C25—C24—C23	113.2 (3)
C5—C4—H4	123.9	C25—C24—H24	123.4
C3—C4—H4	123.9	C23—C24—H24	123.4
C4—C5—C6	112.7 (3)	C24—C25—C26	112.8 (2)
C4—C5—H5	123.7	C24—C25—H25	123.6
C6—C5—H5	123.7	C26—C25—H25	123.6
C5—C6—C7	115.5 (2)	C25—C26—C27	114.22 (19)
C5—C6—C2	103.2 (2)	C25—C26—C22	102.95 (19)
C7—C6—C2	102.69 (19)	C27—C26—C22	102.96 (18)
C5—C6—H6A	111.6	C25—C26—H26A	112.0
C7—C6—H6A	111.6	C27—C26—H26A	112.0
C2—C6—H6A	111.6	C22—C26—H26A	112.0
C9—C7—C8	122.8 (2)	C29—C27—C28	122.7 (2)
C9—C7—C6	128.1 (2)	C29—C27—C26	128.3 (2)
C8—C7—C6	109.05 (18)	C28—C27—C26	109.02 (18)
O11—C8—O1	119.6 (2)	O31—C28—O21	119.6 (2)
O11—C8—C7	130.1 (2)	O31—C28—C27	130.2 (2)
O1—C8—C7	110.28 (19)	O21—C28—C27	110.2 (2)
O10—C9—C7	120.6 (2)	O30—C29—C27	121.0 (2)
O10—C9—H9A	119.9	O30—C29—H29A	118.2
C7—C9—H9A	119.0	C27—C29—H29A	120.6
C9—O10—H10	105.7	C29—O30—H30	108.2
C8—O1—C2—C3	124.6 (2)	C28—O21—C22—C23	−119.1 (2)
C8—O1—C2—C6	9.2 (3)	C28—O21—C22—C26	−3.5 (3)
O1—C2—C3—C4	−107.1 (2)	O21—C22—C23—C24	110.7 (2)
C6—C2—C3—C4	7.3 (3)	C26—C22—C23—C24	−4.0 (3)
C2—C3—C4—C5	−5.0 (3)	C22—C23—C24—C25	2.7 (3)
C3—C4—C5—C6	0.5 (4)	C23—C24—C25—C26	−0.2 (3)
C4—C5—C6—C7	115.3 (3)	C24—C25—C26—C27	−113.2 (2)
C4—C5—C6—C2	4.1 (3)	C24—C25—C26—C22	−2.3 (3)
O1—C2—C6—C5	110.1 (2)	O21—C22—C26—C25	−113.8 (2)
C3—C2—C6—C5	−7.0 (3)	C23—C22—C26—C25	3.9 (2)
O1—C2—C6—C7	−10.2 (2)	O21—C22—C26—C27	5.2 (2)
C3—C2—C6—C7	−127.3 (2)	C23—C22—C26—C27	122.9 (2)
C5—C6—C7—C9	77.0 (3)	C25—C26—C27—C29	−73.7 (3)
C2—C6—C7—C9	−171.5 (2)	C22—C26—C27—C29	175.5 (2)
C5—C6—C7—C8	−103.2 (2)	C25—C26—C27—C28	105.6 (2)
C2—C6—C7—C8	8.3 (2)	C22—C26—C27—C28	−5.2 (2)
C2—O1—C8—O11	176.1 (2)	C22—O21—C28—O31	−179.3 (2)
C2—O1—C8—C7	−4.1 (3)	C22—O21—C28—C27	0.2 (3)
C9—C7—C8—O11	−3.4 (4)	C29—C27—C28—O31	2.2 (4)
C6—C7—C8—O11	176.8 (2)	C26—C27—C28—O31	−177.1 (2)
C9—C7—C8—O1	176.7 (2)	C29—C27—C28—O21	−177.3 (2)
C6—C7—C8—O1	−3.1 (3)	C26—C27—C28—O21	3.4 (3)
C8—C7—C9—O10	−179.40 (19)	C28—C27—C29—O30	179.3 (2)
C6—C7—C9—O10	0.4 (4)	C26—C27—C29—O30	−1.5 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O10—H10···O31	0.93	1.75	2.644 (2)	161
O10—H10···O21	0.93	2.59	3.218 (2)	125
O30—H30···O11^i	0.94	1.77	2.651 (2)	154

Symmetry code: (i) x+1, y, z.