organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890
Volume 69| Part 8| August 2013| Pages o1351-o1352

Bruceolline J: 2-hy­dr­oxy-3,3-di­methyl-2,3-di­hydro­cyclo­penta­[b]indol-1(4H)-one

aDepartment of Chemistry, Dartmouth College, Hanover, NH 03755-3564, USA, and bDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA
*Correspondence e-mail: jjasinski@keene.edu

(Received 20 July 2013; accepted 23 July 2013; online 31 July 2013)

The 12-membered cyclo­penta­[b]indole ring system in the title compound, C13H13NO2, deviates only slightly from planarity (r.m.s. deviation = 0.051 Å). In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the mol­ecules into sheets parallel to (100). The five-membered cyclopentanone ring is in slightly distorted envelope conformation with the C atom bearing the hydroxy substituent as the flap.

Related literature

For a review of compounds isolated from Brucea sp. plants, see: Liu et al. (2009[Liu, J.-H., Jin, H.-Z., Zhang, W.-D., Yan, S.-K. & Shen, Y.-H. (2009). Chem. Biodivers. 6, 57-70.]). For the first isolation of bruceolline J, see: Chen et al. (2011[Chen, H., Bai, J., Fang, Z.-F., Yu, S.-S., Ma, S.-G., Xu, S., Li, Y., Qu, J., Ren, J.-H., Li, L., Si, Y.-K. & Chen, X.-G. (2011). J. Nat. Prod. 74, 2438-244.]). For the DDQ-mediated selective oxidation of indole side chains, see: Oikawa & Yonemitsu (1977[Oikawa, Y. & Yonemitsu, O. (1977). J. Org. Chem. 42, 1213-1216.]). For examples of the reduction of α-keto esters with sodium borohydride, see Dalla et al. (1999[Dalla, V., Catteau, J. P. & Pale, P. (1999). Tetrahedron Lett. 40, 5193-5196.]). For the enanti­oselective reduction of related sterically hindered ketones with β-chloro­diisopinocampheylborane, see: Brown et al. (1986[Brown, H. C., Chandrasekharan, J. & Ramachandran, P. V. (1986). J. Org. Chem. 51, 3396-3398.]). For the isolation of related bruceollines, see: Ouyang et al. (1994a[Ouyang, Y., Koike, K. & Ohmoto, T. (1994a). Phytochemistry, 36, 1543-1546.],b[Ouyang, Y., Koike, K. & Ohmoto, T. (1994b). Phytochemistry, 37, 575-578.], 1995[Ouyang, Y., Mitsunaga, K., Koike, K. & Ohmoto, T. (1995). Phytochemistry, 39, 911-913.]). For the crystal structure of bruceolline D, see: Lopchuk et al. (2013[Lopchuk, J. M., Gribble, G. W. & Jasinski, J. P. (2013). Acta Cryst. E69, o1043.]). For the total synthesis and crystal structure of bruceolline E, see: Jordan et al. (2011[Jordan, J. A., Gribble, G. W. & Badenock, J. C. (2011). Tetrahedron Lett. 52, 6772-6774.], 2012)[Jordon, J. A., Badenock, J. C., Gribble, G. W., Jasinski, J. P. & Golen, J. A. (2012). Acta Cryst. E68, o364-o365.]. For bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]).

[Scheme 1]

Experimental

Crystal data
  • C13H13NO2

  • Mr = 215.24

  • Monoclinic, P 21 /c

  • a = 8.2951 (3) Å

  • b = 12.3070 (4) Å

  • c = 10.7340 (4) Å

  • β = 97.207 (3)°

  • V = 1087.15 (7) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 173 K

  • 0.44 × 0.38 × 0.34 mm

Data collection
  • Agilent Xcalibur (Eos, Gemini) diffractometer

  • Absorption correction: multi-scan (CrysAlis PRO and CrysAlis RED; Agilent, 2012[Agilent (2012). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.]) Tmin = 0.782, Tmax = 1.000

  • 13545 measured reflections

  • 3753 independent reflections

  • 2888 reflections with I > 2σ(I)

  • Rint = 0.035

Refinement
  • R[F2 > 2σ(F2)] = 0.048

  • wR(F2) = 0.134

  • S = 1.04

  • 3753 reflections

  • 148 parameters

  • H-atom parameters constrained

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.25 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O2—H2⋯O1i 0.84 1.90 2.7245 (12) 168
N1—H1⋯O2ii 0.88 1.91 2.7500 (12) 158
Symmetry codes: (i) -x+2, -y+1, -z+2; (ii) [-x+2, y-{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: CrysAlis PRO (Agilent, 2012[Agilent (2012). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007[Palatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786-790.]); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: XP in SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: XP in SHELXTL.

Supporting information


Comment top

Bruceolline J is a cyclopenta[b]indole alkaloid which has been recently isolated from the stems of Brucea mollis Wall (Chen et al., 2011). Our total synthesis of racemic bruceolline J was achieved by the oxidation of bruceolline D to bruceolline E with DDQ followed by the selective reduction of bruceolline E with sodium borohydride in 98% yield. Enantioselective reductions with β-chlorodiisopinocampheylborane gave both the natural and unnatural enantiomers in excellent yields and enantioselectivites. Further isolation studies of the Brucea mollis shrubs have resulted in the discovery of a myriad of other bruceollines and cathan-6-one alkaloids (Ouyang et al., 1994a; Ouyang et al., 1994b; Ouyang et al., 1995). Although there has been limited attention from the synthetic community given to these compounds, a previous synthesis of bruceolline E has been reported (Jordan et al., 2011). The crystal structures of bruceolline D (Lopchuk et al., 2013) and bruceolline E (Jordon et al., 2012) have been disclosed. In view of the importance of cyclopenta[b]indole alkaloids, we report here the crystal structure of the title compound, C13H13NO2, (I).

The title compound, crystallizes with one molecule in the asymmetric unit. The 12-membered cyclopenta[b]indole ring system deviates only slightly from planarity (r.m.s. deviation 0.051Å) (Fig. 1). The 5-membered cyclopentanone ring is in slightly distorted envelope configuration (Q= 0.1012 (12)Å, ϕ = 66.4 (7)°) with C3 as the flap Bond lengths are in normal ranges (Allen et al., 1987). In the crystal N—H···O and O—H···O hydrogen bonds (Table 1) link the molecules into sheets parallel to (1 0 0) and contribute to crystal packing stability (Fig. 2).

Related literature top

For a review of compounds isolated from Brucea sp. plants, see: Liu et al. (2009). For the first isolation of bruceolline J, see: Chen et al. (2011). For the DDQ-mediated selective oxidation of indole side chains, see: Oikawa & Yonemitsu (1977). For examples of the reduction of α-keto esters with sodium borohydride, see Dalla et al. (1999). For the enantioselective reduction of related sterically hindered ketones with β-chlorodiisopinocampheylborane, see: Brown et al. (1986). For the isolation of related bruceollines, see: Ouyang et al. (1994a,b, 1995). For the crystal structure of bruceolline D, see: Lopchuk et al. (2013). For the total synthesis and crystal structure of bruceolline E, see: Jordan et al. (2011, 2012). For bond-length data, see: Allen et al. (1987).

Experimental top

To an ice-cold solution of bruceolline E (50 mg, 0.234 mmol, 1.0 equiv.) in dry THF (10 mL) was added sodium borohydride (5 mg, 0.117 mmol, 0.5 equiv.) in one portion (Fig. 3). After stirring at 0°C for 5 minutes, the reaction was quenched with water (5 mL) and concentrated to half the original volume. The mixture was extracted with ethyl acetate (3 x 40 mL). The organic extracts were combined, dried over Na2SO4, and concentrated in vacuo to an off-white solid. The residue was purified by flash chromatography (50% ethyl acetate in pentane) to afford the desired product (I) as a white solid (50 mg, 98% yield). Single crystals suitable for diffraction were grown from ethyl acetate (slow evaporation) at ambient temperature [m.p. 466-467 K (dec); no literature value available].

Refinement top

All H atoms were found in a difference map. Nevertheless, they were placed in their calculated positions and then refined using the riding model with Atom—H lengths of 0.95Å, 1.000Å (CH), 0.98Å (CH3), 0.88Å (NH) or 0.84Å (OH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, NH) or 1.5 (CH3, OH) times Ueq of the parent atom. The methyl groups and the hydroxyl group were refined as rotating groups allowed to rotate but not to tip.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: XP in SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound showing the atom labeling scheme and 30% probability displacement ellipsoids.
[Figure 2] Fig. 2. Packing diagram of the title compound viewed along the b axis. Dashed lines indicate N—H···O and O—H···O hydrogen bonds forming sheets parallel to (1 0 0). H atoms not involved hydrogen bonding have been deleted for clarity.
[Figure 3] Fig. 3. Synthesis of (I).
2-Hydroxy-3,3-dimethyl-2,3-dihydrocyclopenta[b]indol-1(4H)-one top
Crystal data top
C13H13NO2F(000) = 456
Mr = 215.24Dx = 1.315 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.7107 Å
a = 8.2951 (3) ÅCell parameters from 3528 reflections
b = 12.3070 (4) Åθ = 3.3–32.9°
c = 10.7340 (4) ŵ = 0.09 mm1
β = 97.207 (3)°T = 173 K
V = 1087.15 (7) Å3Irregular, colourless
Z = 40.44 × 0.38 × 0.34 mm
Data collection top
Agilent Xcalibur (Eos, Gemini)
diffractometer
3753 independent reflections
Radiation source: Enhance (Mo) X-ray Source2888 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
Detector resolution: 16.0416 pixels mm-1θmax = 33.0°, θmin = 3.4°
ω scansh = 1212
Absorption correction: multi-scan
(CrysAlis PRO and CrysAlis RED; Agilent, 2012)
k = 1718
Tmin = 0.782, Tmax = 1.000l = 1615
13545 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.048H-atom parameters constrained
wR(F2) = 0.134 w = 1/[σ2(Fo2) + (0.0662P)2 + 0.2062P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
3753 reflectionsΔρmax = 0.40 e Å3
148 parametersΔρmin = 0.25 e Å3
0 restraints
Crystal data top
C13H13NO2V = 1087.15 (7) Å3
Mr = 215.24Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.2951 (3) ŵ = 0.09 mm1
b = 12.3070 (4) ÅT = 173 K
c = 10.7340 (4) Å0.44 × 0.38 × 0.34 mm
β = 97.207 (3)°
Data collection top
Agilent Xcalibur (Eos, Gemini)
diffractometer
3753 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO and CrysAlis RED; Agilent, 2012)
2888 reflections with I > 2σ(I)
Tmin = 0.782, Tmax = 1.000Rint = 0.035
13545 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0480 restraints
wR(F2) = 0.134H-atom parameters constrained
S = 1.04Δρmax = 0.40 e Å3
3753 reflectionsΔρmin = 0.25 e Å3
148 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.83909 (11)0.55666 (6)0.93513 (8)0.03008 (19)
O21.13253 (11)0.51818 (7)0.82424 (8)0.0297 (2)
H21.15520.49330.89720.045*
N10.76891 (11)0.21451 (7)0.76238 (9)0.0246 (2)
H10.79450.16020.71520.030*
C10.83979 (13)0.31258 (8)0.77083 (10)0.0221 (2)
C20.98429 (13)0.35821 (9)0.71904 (10)0.0233 (2)
C30.98044 (14)0.47719 (8)0.77069 (10)0.0242 (2)
H30.93980.52540.69860.029*
C40.85291 (13)0.47926 (8)0.86414 (9)0.0230 (2)
C50.76844 (13)0.37877 (9)0.85201 (10)0.0233 (2)
C60.64335 (13)0.31588 (9)0.90039 (10)0.0239 (2)
C70.53565 (14)0.33227 (11)0.98851 (11)0.0301 (2)
H70.52980.40061.02900.036*
C80.43771 (15)0.24690 (12)1.01561 (13)0.0365 (3)
H80.36500.25671.07640.044*
C90.44313 (15)0.14681 (12)0.95594 (14)0.0383 (3)
H90.37390.08990.97680.046*
C100.54722 (15)0.12837 (10)0.86689 (13)0.0333 (3)
H100.54980.06040.82520.040*
C110.64742 (13)0.21344 (9)0.84131 (10)0.0249 (2)
C121.13707 (14)0.29740 (10)0.77445 (12)0.0309 (2)
H12A1.23320.33430.75030.046*
H12B1.13320.22280.74240.046*
H12C1.14290.29610.86620.046*
C130.96704 (18)0.35481 (12)0.57537 (11)0.0364 (3)
H13A0.86640.39170.54110.055*
H13B0.96360.27900.54710.055*
H13C1.06010.39160.54600.055*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0424 (5)0.0199 (4)0.0285 (4)0.0036 (3)0.0066 (3)0.0047 (3)
O20.0386 (5)0.0241 (4)0.0273 (4)0.0099 (3)0.0075 (3)0.0006 (3)
N10.0267 (4)0.0190 (4)0.0284 (4)0.0002 (3)0.0046 (3)0.0042 (3)
C10.0248 (5)0.0199 (4)0.0216 (4)0.0009 (4)0.0033 (3)0.0015 (4)
C20.0279 (5)0.0229 (5)0.0197 (4)0.0015 (4)0.0056 (4)0.0019 (4)
C30.0332 (6)0.0189 (4)0.0210 (5)0.0019 (4)0.0051 (4)0.0009 (4)
C40.0303 (5)0.0184 (4)0.0201 (4)0.0036 (4)0.0023 (4)0.0001 (3)
C50.0266 (5)0.0210 (5)0.0228 (5)0.0021 (4)0.0056 (4)0.0008 (4)
C60.0233 (5)0.0238 (5)0.0245 (5)0.0022 (4)0.0027 (4)0.0020 (4)
C70.0265 (5)0.0358 (6)0.0289 (5)0.0046 (4)0.0064 (4)0.0019 (5)
C80.0271 (6)0.0474 (7)0.0364 (6)0.0022 (5)0.0090 (5)0.0099 (6)
C90.0282 (6)0.0386 (7)0.0485 (8)0.0043 (5)0.0068 (5)0.0136 (6)
C100.0293 (6)0.0262 (6)0.0436 (7)0.0029 (4)0.0022 (5)0.0052 (5)
C110.0232 (5)0.0227 (5)0.0283 (5)0.0013 (4)0.0017 (4)0.0023 (4)
C120.0276 (6)0.0250 (5)0.0405 (6)0.0014 (4)0.0062 (4)0.0033 (5)
C130.0477 (7)0.0408 (7)0.0217 (5)0.0070 (6)0.0080 (5)0.0050 (5)
Geometric parameters (Å, º) top
O1—C41.2341 (13)C6—C111.4136 (15)
O2—H20.8400C7—H70.9500
O2—C31.4122 (14)C7—C81.3812 (19)
N1—H10.8800C8—H80.9500
N1—C11.3406 (13)C8—C91.392 (2)
N1—C111.3956 (14)C9—H90.9500
C1—C21.4928 (15)C9—C101.3849 (19)
C1—C51.3793 (14)C10—H100.9500
C2—C31.5675 (15)C10—C111.3854 (16)
C2—C121.5267 (16)C12—H12A0.9800
C2—C131.5313 (15)C12—H12B0.9800
C3—H31.0000C12—H12C0.9800
C3—C41.5467 (15)C13—H13A0.9800
C4—C51.4194 (15)C13—H13B0.9800
C5—C61.4425 (15)C13—H13C0.9800
C6—C71.3948 (15)
C3—O2—H2109.5C6—C7—H7120.8
C1—N1—H1125.9C8—C7—C6118.46 (12)
C1—N1—C11108.15 (9)C8—C7—H7120.8
C11—N1—H1125.9C7—C8—H8119.2
N1—C1—C2132.79 (9)C7—C8—C9121.50 (12)
N1—C1—C5110.80 (10)C9—C8—H8119.2
C5—C1—C2116.19 (9)C8—C9—H9119.3
C1—C2—C399.60 (8)C10—C9—C8121.45 (11)
C1—C2—C12109.66 (9)C10—C9—H9119.3
C1—C2—C13112.76 (9)C9—C10—H10121.5
C12—C2—C3111.89 (9)C9—C10—C11117.03 (12)
C12—C2—C13110.31 (10)C11—C10—H10121.5
C13—C2—C3112.23 (9)N1—C11—C6108.88 (9)
O2—C3—C2114.89 (9)C10—C11—N1128.63 (11)
O2—C3—H3107.5C10—C11—C6122.44 (11)
O2—C3—C4112.27 (8)C2—C12—H12A109.5
C2—C3—H3107.5C2—C12—H12B109.5
C4—C3—C2106.90 (8)C2—C12—H12C109.5
C4—C3—H3107.5H12A—C12—H12B109.5
O1—C4—C3122.49 (10)H12A—C12—H12C109.5
O1—C4—C5130.25 (10)H12B—C12—H12C109.5
C5—C4—C3107.22 (8)C2—C13—H13A109.5
C1—C5—C4109.06 (9)C2—C13—H13B109.5
C1—C5—C6107.19 (10)C2—C13—H13C109.5
C4—C5—C6143.48 (10)H13A—C13—H13B109.5
C7—C6—C5135.84 (11)H13A—C13—H13C109.5
C7—C6—C11119.12 (10)H13B—C13—H13C109.5
C11—C6—C5104.97 (9)
O1—C4—C5—C1172.60 (11)C4—C5—C6—C11173.69 (15)
O1—C4—C5—C60.2 (2)C5—C1—C2—C37.02 (12)
O2—C3—C4—O141.66 (14)C5—C1—C2—C12110.49 (11)
O2—C3—C4—C5136.56 (9)C5—C1—C2—C13126.17 (11)
N1—C1—C2—C3178.95 (11)C5—C6—C7—C8175.79 (12)
N1—C1—C2—C1263.53 (15)C5—C6—C11—N10.33 (12)
N1—C1—C2—C1359.81 (16)C5—C6—C11—C10177.91 (11)
N1—C1—C5—C4176.56 (9)C6—C7—C8—C90.91 (19)
N1—C1—C5—C61.03 (13)C7—C6—C11—N1177.07 (10)
C1—N1—C11—C60.28 (12)C7—C6—C11—C100.51 (17)
C1—N1—C11—C10177.10 (12)C7—C8—C9—C100.1 (2)
C1—C2—C3—O2134.83 (9)C8—C9—C10—C110.97 (19)
C1—C2—C3—C49.56 (10)C9—C10—C11—N1175.78 (11)
C1—C5—C6—C7175.93 (13)C9—C10—C11—C61.28 (18)
C1—C5—C6—C110.81 (12)C11—N1—C1—C2173.45 (11)
C2—C1—C5—C41.24 (13)C11—N1—C1—C50.82 (12)
C2—C1—C5—C6174.29 (9)C11—C6—C7—C80.61 (17)
C2—C3—C4—O1168.51 (10)C12—C2—C3—O219.00 (12)
C2—C3—C4—C59.72 (11)C12—C2—C3—C4106.28 (10)
C3—C4—C5—C15.44 (12)C13—C2—C3—O2105.63 (11)
C3—C4—C5—C6178.25 (14)C13—C2—C3—C4129.09 (10)
C4—C5—C6—C73.0 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.841.902.7245 (12)168
N1—H1···O2ii0.881.912.7500 (12)158
Symmetry codes: (i) x+2, y+1, z+2; (ii) x+2, y1/2, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.841.902.7245 (12)168.2
N1—H1···O2ii0.881.912.7500 (12)157.8
Symmetry codes: (i) x+2, y+1, z+2; (ii) x+2, y1/2, z+3/2.
 

Acknowledgements

JML acknowledges support from a Graduate Assistance in Areas of National Need (GAANN) fellowship. GWG acknowledges support by the Donors of the Petroleum Research Fund (PRF), administered by the American Chemical Society, and by Wyeth. JPJ acknowledges the NSF MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.

References

First citationAgilent (2012). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.
First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CrossRef Web of Science
First citationBrown, H. C., Chandrasekharan, J. & Ramachandran, P. V. (1986). J. Org. Chem. 51, 3396–3398.  CrossRef CAS Web of Science
First citationChen, H., Bai, J., Fang, Z.-F., Yu, S.-S., Ma, S.-G., Xu, S., Li, Y., Qu, J., Ren, J.-H., Li, L., Si, Y.-K. & Chen, X.-G. (2011). J. Nat. Prod. 74, 2438–244.  Web of Science CrossRef CAS PubMed
First citationDalla, V., Catteau, J. P. & Pale, P. (1999). Tetrahedron Lett. 40, 5193–5196.  Web of Science CrossRef CAS
First citationJordan, J. A., Gribble, G. W. & Badenock, J. C. (2011). Tetrahedron Lett. 52, 6772–6774.  Web of Science CrossRef CAS
First citationJordon, J. A., Badenock, J. C., Gribble, G. W., Jasinski, J. P. & Golen, J. A. (2012). Acta Cryst. E68, o364–o365.  Web of Science CSD CrossRef CAS IUCr Journals
First citationLiu, J.-H., Jin, H.-Z., Zhang, W.-D., Yan, S.-K. & Shen, Y.-H. (2009). Chem. Biodivers. 6, 57–70.  CrossRef PubMed CAS
First citationLopchuk, J. M., Gribble, G. W. & Jasinski, J. P. (2013). Acta Cryst. E69, o1043.  CSD CrossRef IUCr Journals
First citationOikawa, Y. & Yonemitsu, O. (1977). J. Org. Chem. 42, 1213–1216.  CrossRef CAS Web of Science
First citationOuyang, Y., Koike, K. & Ohmoto, T. (1994a). Phytochemistry, 36, 1543–1546.  CrossRef CAS PubMed Web of Science
First citationOuyang, Y., Koike, K. & Ohmoto, T. (1994b). Phytochemistry, 37, 575–578.  CAS
First citationOuyang, Y., Mitsunaga, K., Koike, K. & Ohmoto, T. (1995). Phytochemistry, 39, 911–913.  CrossRef CAS Web of Science
First citationPalatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786–790.  Web of Science CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals

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Volume 69| Part 8| August 2013| Pages o1351-o1352
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