(–)-Isosantonic acid: alteration of the hydrogen-bonding mode by configurational inversion at a single centre in a γ,[epsilon]-diketocarboxylic acid

The title diketo acid, (1R,3aS,6aS,7R,9S)-(−)-α,3a,7-tri­methyl-5,8-dioxo-1,4-ethano­perhydro­penta­lene-1-acetic acid (C₁₅H₂₀O₄), is shown to aggregate in the crystal structure as acid-to-ketone hydrogen-bonding catemers, whose chains follow 2₁ screw axes from each carboxyl to a ketone in a neighbouring mol­ecule [O...O = 2.7472 (13) Å and O...H—O = 172.7 (17)°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonding chains pass through the cell in the a direction. Six inter­molecular C—H...O=C close contacts are found. Comparisons are drawn with a diastereomer having the opposite configuration at the methyl­ated chiral centre adjacent to the carboxyl group.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.025
• wR factor = 0.066
• Data-to-parameter ratio = 9.2

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT708_ALERT_1_A D-H..A  Calc   172.8(17), Rep    1727(17), Dev..     914.24 Sigma
              O4   -H4   -O1      1.555   1.555   4.456

Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.36 Ratio
PLAT480_ALERT_4_C Long H...A H-Bond Reported H11B   ..  O2      ..       2.65 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H3A    ..  O3      ..       2.67 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H6A    ..  O3      ..       2.65 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H9A    ..  O4      ..       2.67 Ang.
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          1

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           69.24
           From the CIF: _reflns_number_total               2321
           Count of symmetry unique reflns         1451
           Completeness (_total/calc)            159.96%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       870
           Fraction of Friedel pairs measured     0.600
           Are heavy atom types Z>Si present         no

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

   1 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
   6 ALERT type 4 Improvement, methodology, query or suggestion

---

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

(1R,3aS,6aS,7R,9S)-(-)-α,3a,7-trimethyl-5,8-dioxo-1,4- ethanoperhydropentalene-1-acetic acid'

Crystal data

C15H20O4	Dx = 1.317 Mg m^−3
Mr = 264.31	Melting point: 424 K
Orthorhombic, P212121	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: P 2ac 2ab	Cell parameters from 7889 reflections
a = 8.3801 (2) Å	θ = 3.5–68.3°
b = 12.5398 (2) Å	µ = 0.77 mm^−1
c = 12.6852 (2) Å	T = 100 K
V = 1333.02 (4) Å^3	Parallelepiped, colourless
Z = 4	0.50 × 0.34 × 0.26 mm
F(000) = 568

Data collection

Bruker SMART CCD area-detector diffractometer	2321 independent reflections
Radiation source: fine-focus sealed tube	2320 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
φ and ω scans	θmax = 69.2°, θmin = 5.0°
Absorption correction: multi-scan (SADABS; Blessing, 1995)	h = −10→7
Tmin = 0.750, Tmax = 0.820	k = −14→14
15403 measured reflections	l = −14→14

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.025	w = 1/[σ^2(Fo^2) + (0.0435P)^2 + 0.3883P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.066	(Δ/σ)max < 0.001
S = 0.98	Δρmax = 0.21 e Å^−3
2321 reflections	Δρmin = −0.16 e Å^−3
253 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0065 (5)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), with 950 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.02 (15)

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	1.14506 (11)	0.39121 (7)	0.70118 (7)	0.0190 (2)
O2	0.95141 (14)	0.17671 (8)	0.91770 (8)	0.0296 (3)
O3	0.73503 (11)	0.34672 (7)	0.40368 (7)	0.0203 (2)
O4	0.84988 (12)	0.19150 (7)	0.44684 (7)	0.0185 (2)
H4	0.782 (2)	0.1709 (14)	0.4018 (15)	0.030 (5)*
C1	0.87342 (15)	0.37129 (10)	0.63724 (10)	0.0152 (3)
C2	0.75242 (16)	0.46516 (10)	0.63621 (10)	0.0172 (3)
H2A	0.8074 (19)	0.5350 (13)	0.6420 (12)	0.018 (4)*
H2B	0.6986 (17)	0.4610 (11)	0.5717 (12)	0.011 (3)*
C3	0.63359 (16)	0.44360 (11)	0.72692 (10)	0.0192 (3)
H3A	0.6419 (18)	0.5026 (12)	0.7797 (11)	0.013 (3)*
H3B	0.523 (2)	0.4405 (13)	0.7019 (13)	0.022 (4)*
C3A	0.67768 (16)	0.33365 (11)	0.77273 (9)	0.0177 (3)
C4	0.80962 (16)	0.33636 (11)	0.85842 (10)	0.0175 (3)
H4A	0.7690 (18)	0.3505 (12)	0.9273 (13)	0.015 (4)*
C5	0.88472 (16)	0.22579 (10)	0.84861 (10)	0.0196 (3)
C6	0.86504 (18)	0.18840 (11)	0.73454 (10)	0.0193 (3)
H6A	0.967 (2)	0.1755 (14)	0.7049 (13)	0.025 (4)*
H6B	0.806 (2)	0.1209 (13)	0.7346 (13)	0.022 (4)*
C6A	0.77071 (16)	0.27819 (10)	0.68215 (10)	0.0169 (3)
H6AA	0.6968 (18)	0.2542 (12)	0.6247 (12)	0.016 (4)*
C7	0.94270 (16)	0.41824 (10)	0.83122 (10)	0.0177 (3)
H7A	0.892 (2)	0.4885 (14)	0.8272 (12)	0.023 (4)*
C8	1.00268 (15)	0.39464 (9)	0.72008 (10)	0.0148 (3)
C9	0.95204 (15)	0.34666 (10)	0.52941 (9)	0.0149 (3)
H9A	1.0327 (18)	0.2935 (12)	0.5410 (11)	0.011 (3)*
C10	0.83327 (15)	0.29750 (10)	0.45385 (9)	0.0151 (3)
C11	1.02581 (16)	0.44569 (11)	0.47779 (10)	0.0171 (3)
H11A	1.0710 (18)	0.4254 (12)	0.4100 (13)	0.017 (4)*
H11B	1.108 (2)	0.4776 (13)	0.5243 (13)	0.019 (4)*
H11C	0.944 (2)	0.4979 (13)	0.4623 (12)	0.021 (4)*
C12	1.07672 (17)	0.42128 (11)	0.91236 (11)	0.0212 (3)
H12A	1.132 (2)	0.3529 (15)	0.9161 (14)	0.030 (4)*
H12B	1.034 (2)	0.4399 (15)	0.9830 (16)	0.037 (5)*
H12C	1.154 (2)	0.4738 (15)	0.8949 (14)	0.029 (4)*
C13	0.53463 (18)	0.26979 (12)	0.81207 (10)	0.0236 (3)
H13A	0.481 (2)	0.3067 (15)	0.8684 (15)	0.031 (5)*
H13B	0.566 (2)	0.1979 (16)	0.8382 (15)	0.035 (5)*
H13C	0.457 (2)	0.2576 (13)	0.7560 (14)	0.023 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0169 (5)	0.0213 (5)	0.0188 (5)	0.0004 (4)	−0.0009 (4)	−0.0032 (4)
O2	0.0450 (6)	0.0225 (5)	0.0214 (5)	0.0026 (5)	−0.0066 (5)	0.0042 (4)
O3	0.0203 (5)	0.0210 (5)	0.0196 (5)	−0.0004 (4)	−0.0045 (4)	0.0019 (4)
O4	0.0185 (5)	0.0184 (5)	0.0186 (4)	0.0003 (4)	−0.0018 (4)	−0.0036 (4)
C1	0.0176 (6)	0.0141 (6)	0.0141 (6)	−0.0003 (5)	−0.0013 (5)	−0.0002 (5)
C2	0.0183 (7)	0.0182 (6)	0.0151 (6)	0.0022 (6)	−0.0012 (5)	−0.0005 (5)
C3	0.0171 (7)	0.0240 (7)	0.0166 (6)	0.0035 (5)	0.0008 (5)	−0.0031 (5)
C3A	0.0179 (6)	0.0214 (7)	0.0138 (6)	0.0005 (5)	0.0007 (5)	−0.0029 (5)
C4	0.0213 (7)	0.0199 (7)	0.0113 (6)	−0.0003 (5)	0.0008 (5)	−0.0009 (5)
C5	0.0221 (7)	0.0190 (7)	0.0177 (6)	−0.0031 (5)	0.0008 (5)	0.0025 (5)
C6	0.0240 (7)	0.0163 (7)	0.0175 (6)	−0.0008 (6)	0.0016 (5)	0.0003 (5)
C6A	0.0188 (6)	0.0184 (6)	0.0134 (6)	−0.0022 (5)	0.0003 (5)	−0.0017 (5)
C7	0.0201 (6)	0.0163 (6)	0.0166 (6)	0.0019 (6)	−0.0013 (5)	−0.0011 (5)
C8	0.0186 (7)	0.0093 (5)	0.0166 (6)	0.0014 (5)	−0.0015 (5)	0.0002 (5)
C9	0.0150 (6)	0.0161 (6)	0.0138 (6)	0.0018 (5)	−0.0004 (5)	−0.0001 (4)
C10	0.0157 (6)	0.0169 (6)	0.0126 (6)	−0.0007 (5)	0.0039 (5)	0.0012 (5)
C11	0.0183 (6)	0.0183 (6)	0.0145 (6)	−0.0015 (6)	0.0004 (5)	0.0000 (5)
C12	0.0227 (7)	0.0244 (7)	0.0165 (6)	−0.0008 (6)	−0.0028 (5)	−0.0017 (5)
C13	0.0227 (7)	0.0320 (8)	0.0161 (6)	−0.0034 (6)	0.0026 (6)	−0.0012 (6)

Geometric parameters (Å, º)

O1—C8	1.2178 (17)	C5—C6	1.5300 (18)
O2—C5	1.2080 (17)	C6—C6A	1.5279 (18)
O3—C10	1.2098 (15)	C6—H6A	0.945 (18)
O4—C10	1.3394 (16)	C6—H6B	0.981 (17)
O4—H4	0.847 (19)	C6A—H6AA	1.002 (15)
C1—C8	1.5373 (17)	C7—C12	1.5239 (18)
C1—C9	1.5493 (17)	C7—C8	1.5258 (17)
C1—C2	1.5537 (17)	C7—H7A	0.979 (18)
C1—C6A	1.5583 (17)	C9—C10	1.5131 (18)
C2—C3	1.5456 (18)	C9—C11	1.5340 (17)
C2—H2A	0.992 (16)	C9—H9A	0.960 (15)
C2—H2B	0.936 (15)	C11—H11A	0.974 (17)
C3—C3A	1.5412 (19)	C11—H11B	0.991 (17)
C3—H3A	1.001 (15)	C11—H11C	0.968 (18)
C3—H3B	0.984 (18)	C12—H12A	0.976 (19)
C3A—C13	1.5256 (19)	C12—H12B	0.99 (2)
C3A—C4	1.5508 (18)	C12—H12C	0.949 (19)
C3A—C6A	1.5530 (17)	C13—H13A	0.962 (19)
C4—C5	1.5278 (19)	C13—H13B	0.996 (19)
C4—C7	1.5547 (19)	C13—H13C	0.977 (18)
C4—H4A	0.955 (16)
C10—O4—H4	106.1 (12)	C6—C6A—C1	115.18 (11)
C8—C1—C9	109.99 (10)	C3A—C6A—C1	102.26 (10)
C8—C1—C2	108.75 (10)	C6—C6A—H6AA	114.5 (9)
C9—C1—C2	114.91 (10)	C3A—C6A—H6AA	111.2 (8)
C8—C1—C6A	106.38 (10)	C1—C6A—H6AA	107.5 (9)
C9—C1—C6A	114.09 (10)	C12—C7—C8	112.72 (11)
C2—C1—C6A	102.13 (10)	C12—C7—C4	113.29 (11)
C3—C2—C1	106.36 (10)	C8—C7—C4	108.25 (10)
C3—C2—H2A	113.5 (9)	C12—C7—H7A	109.3 (10)
C1—C2—H2A	111.4 (9)	C8—C7—H7A	105.6 (9)
C3—C2—H2B	109.3 (9)	C4—C7—H7A	107.2 (10)
C1—C2—H2B	106.2 (9)	O1—C8—C7	120.77 (11)
H2A—C2—H2B	109.8 (13)	O1—C8—C1	123.30 (11)
C3A—C3—C2	106.43 (10)	C7—C8—C1	115.88 (11)
C3A—C3—H3A	113.1 (8)	C10—C9—C11	108.94 (10)
C2—C3—H3A	108.9 (9)	C10—C9—C1	111.15 (10)
C3A—C3—H3B	108.2 (10)	C11—C9—C1	112.76 (10)
C2—C3—H3B	112.1 (10)	C10—C9—H9A	106.1 (8)
H3A—C3—H3B	108.1 (13)	C11—C9—H9A	110.1 (9)
C13—C3A—C3	113.86 (11)	C1—C9—H9A	107.6 (8)
C13—C3A—C4	110.03 (10)	O3—C10—O4	122.82 (12)
C3—C3A—C4	114.56 (11)	O3—C10—C9	124.96 (11)
C13—C3A—C6A	113.67 (11)	O4—C10—C9	112.21 (11)
C3—C3A—C6A	104.00 (10)	C9—C11—H11A	108.8 (9)
C4—C3A—C6A	99.82 (10)	C9—C11—H11B	110.7 (9)
C5—C4—C3A	102.51 (10)	H11A—C11—H11B	111.2 (13)
C5—C4—C7	106.61 (11)	C9—C11—H11C	110.4 (9)
C3A—C4—C7	111.74 (10)	H11A—C11—H11C	105.8 (13)
C5—C4—H4A	113.0 (9)	H11B—C11—H11C	109.9 (13)
C3A—C4—H4A	113.0 (9)	C7—C12—H12A	111.1 (11)
C7—C4—H4A	109.7 (9)	C7—C12—H12B	110.6 (11)
O2—C5—C4	126.43 (12)	H12A—C12—H12B	109.4 (15)
O2—C5—C6	125.45 (12)	C7—C12—H12C	111.1 (11)
C4—C5—C6	108.10 (11)	H12A—C12—H12C	107.4 (15)
C6A—C6—C5	103.97 (10)	H12B—C12—H12C	107.0 (16)
C6A—C6—H6A	114.8 (10)	C3A—C13—H13A	110.8 (11)
C5—C6—H6A	109.3 (10)	C3A—C13—H13B	112.0 (11)
C6A—C6—H6B	112.0 (10)	H13A—C13—H13B	108.2 (15)
C5—C6—H6B	108.5 (10)	C3A—C13—H13C	111.6 (10)
H6A—C6—H6B	107.9 (14)	H13A—C13—H13C	107.9 (14)
C6—C6A—C3A	105.54 (10)	H13B—C13—H13C	106.1 (15)
C8—C1—C2—C3	−82.91 (12)	C2—C1—C6A—C6	−156.31 (11)
C9—C1—C2—C3	153.34 (11)	C8—C1—C6A—C3A	71.52 (12)
C6A—C1—C2—C3	29.27 (12)	C9—C1—C6A—C3A	−167.03 (10)
C1—C2—C3—C3A	−4.83 (13)	C2—C1—C6A—C3A	−42.42 (12)
C2—C3—C3A—C13	−146.00 (11)	C5—C4—C7—C12	−67.36 (13)
C2—C3—C3A—C4	86.13 (13)	C3A—C4—C7—C12	−178.61 (11)
C2—C3—C3A—C6A	−21.76 (13)	C5—C4—C7—C8	58.42 (13)
C13—C3A—C4—C5	77.39 (13)	C3A—C4—C7—C8	−52.83 (14)
C3—C3A—C4—C5	−152.82 (11)	C12—C7—C8—O1	−7.51 (17)
C6A—C3A—C4—C5	−42.40 (12)	C4—C7—C8—O1	−133.63 (12)
C13—C3A—C4—C7	−168.80 (11)	C12—C7—C8—C1	169.96 (11)
C3—C3A—C4—C7	−39.01 (15)	C4—C7—C8—C1	43.85 (14)
C6A—C3A—C4—C7	71.42 (12)	C9—C1—C8—O1	−1.44 (16)
C3A—C4—C5—O2	−152.78 (14)	C2—C1—C8—O1	−128.07 (13)
C7—C4—C5—O2	89.69 (16)	C6A—C1—C8—O1	122.59 (13)
C3A—C4—C5—C6	28.72 (13)	C9—C1—C8—C7	−178.84 (10)
C7—C4—C5—C6	−88.81 (12)	C2—C1—C8—C7	54.52 (13)
O2—C5—C6—C6A	178.99 (14)	C6A—C1—C8—C7	−54.81 (13)
C4—C5—C6—C6A	−2.49 (14)	C8—C1—C9—C10	166.09 (10)
C5—C6—C6A—C3A	−24.98 (13)	C2—C1—C9—C10	−70.82 (13)
C5—C6—C6A—C1	86.99 (12)	C6A—C1—C9—C10	46.66 (14)
C13—C3A—C6A—C6	−74.89 (13)	C8—C1—C9—C11	−71.25 (13)
C3—C3A—C6A—C6	160.75 (11)	C2—C1—C9—C11	51.84 (15)
C4—C3A—C6A—C6	42.21 (12)	C6A—C1—C9—C11	169.32 (10)
C13—C3A—C6A—C1	164.30 (11)	C11—C9—C10—O3	−44.88 (16)
C3—C3A—C6A—C1	39.94 (12)	C1—C9—C10—O3	79.95 (15)
C4—C3A—C6A—C1	−78.61 (11)	C11—C9—C10—O4	134.20 (11)
C8—C1—C6A—C6	−42.37 (13)	C1—C9—C10—O4	−100.97 (12)
C9—C1—C6A—C6	79.08 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4···O1^i	0.847 (19)	1.90 (2)	2.7472 (13)	172,7 (17)
C11—H11B···O2^ii	0.991 (17)	2.650 (16)	3.1916 (17)	114.5 (11)
C3—H3A···O3^iii	1.001 (15)	2.666 (15)	3.6268 (16)	161.1 (12)
C6—H6A···O3^iv	0.945 (18)	2.652 (18)	3.5891 (17)	171.4 (14)
C7—H7A···O3^iii	0.979 (18)	2.519 (18)	3.4278 (16)	154.3 (13)
C9—H9A···O3^iv	0.960 (15)	2.542 (16)	3.4964 (15)	172.6 (11)
C9—H9A···O4^iv	0.960 (15)	2.669 (15)	3.3816 (16)	131.3 (11)

Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) −x+2, y+1/2, −z+3/2; (iii) −x+3/2, −y+1, z+1/2; (iv) x+1/2, −y+1/2, −z+1.