Literature DB >> 28529789

3-Hy-droxy-2-phenyl-2,3,3a,7a-tetra-hydro-1H,5H-pyrano[3,2-b]pyrrol-5-one: crystal structure and Hirshfeld surface analysis.

Julio Zukerman-Schpector1, Angélica V Moro2,3, Marcelo R Dos Santos2,4, Carlos Roque D Correia2, Mukesh M Jotani5, Edward R T Tiekink6.   

Abstract

The title isoaltholactone derivative, C13H13NO3, has an NH group in place of the ether-O atom in the five-membered ring of the natural product. The five-membered ring is twisted about the N-C bond linking it to the six-membered ring, which has a half-chair conformation with the O atom connected to the ether-O atom lying above the plane defined by the remaining atoms. The dihedral angle between the mean planes of the rings comprising the fused-ring system is 75.10 (8)°. In the crystal, hy-droxy-O-H⋯N(amine) hydrogen bonding sustains linear supra-molecular chains along the a axis. Chains are linked into a three-dimensional architecture via amine-N-H⋯π(phen-yl) and phenyl-C-H⋯O(hy-droxy) inter-actions. The influence of the amine-N-H⋯π(phen-yl) contact on the mol-ecular packing is revealed by an analysis of the Hirshfeld surface.

Entities:  

Keywords:  Hirshfeld surface analysis; aza-isoaltholactone; crystal structure; hydrogen bonding

Year:  2017        PMID: 28529789      PMCID: PMC5418797          DOI: 10.1107/S2056989017005680

Source DB:  PubMed          Journal:  Acta Crystallogr E Crystallogr Commun


Chemical context

Styryllactones are a diverse group of secondary metabolites which have demonstrated significant potency against a broad spectrum of human tumour cells, including breast, colon, kidney and pancreas cancer lines (Tian et al., 2006 ▸). Other biological activities have also been revealed for this class of compound, namely anti-inflammatory, anti-microbial, anti-fertility and immunosuppressant (de Fatima et al., 2006 ▸). A member of the styryllactone family of compounds is iso­altho­lactone, a natural product which comprises an α,β-unsaturated furan­opyran­one unit, i.e. there is an oxygen atom in place of the NH group in (I) shown in the Scheme. Iso­altho­lactone is structurally notable for its central tetra-substituted tetra­hydro­furan ring, which has four consecutive stereogenic centres. Compound (I), described herein, was originally prepared to enhance the biological activity of isoaltholactone (Moro et al., 2011 ▸). Crystals of (I) have subsequently become available and the present report details the crystal and mol­ecular structures of (I) along with an analysis of the Hirshfeld surface of (I) in order to provide more information on the supra­molecular association.

Structural commentary

The mol­ecular structure of (I) is shown in Fig. 1 ▸. The configurations about the chain of four chiral centres, i.e. C4–C7, are R, S, R and R, respectively. The five-membered pyrrolyl ring is twisted about the N1C4 bond. The six-membered pyranyl ring is best described as having a half-chair conformation where the O1, C1–C4 atoms are co-planar (r.m.s. deviation = 0.0453 Å) and the C5 atom lies 0.435 (3) Å out of the plane. The fused-ring system has, to a first approximation, the shape of the letter V with the dihedral angle between the mean planes through each of the rings being 75.10 (8)°. The oxygen atoms all lie to one side of the plane through the pyrrolyl ring. Finally, the dihedral angle between the pyrrolyl and phenyl rings is 33.11 (7)°, indicating a twisted conformation.
Figure 1

The mol­ecular structure of (I), showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Supra­molecular features

Conventional hy­droxy-O—H⋯N(amine) hydrogen bonding in the crystal of (I) leads to a linear, supra­molecular chain along the a axis as illustrated in Fig. 2 ▸ a, Table 1 ▸. The amine-N—H atom forms an inter­action with the phenyl ring, i.e. amine-N—H⋯π(phen­yl), Table 1 ▸, linking mol­ecules along the c axis, as shown in Fig. 2 ▸ b. The hy­droxy-O atom accepts a weak contact from a phenyl-H atom to connect mol­ecules along the b axis, thereby consolidating the three-dimensional mol­ecular packing (Fig. 2 ▸ b).
Figure 2

Mol­ecular packing in (I): (a) a view of the supra­molecular chain sustained by hy­droxy-O—H⋯N(amine) hydrogen bonding and (b) a view of the unit-cell contents shown in projection down the a axis. The O—H⋯N, N—H⋯π and C—H⋯O inter­actions are shown as orange, purple and blue dashed lines, respectively.

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C8–C13 ring.

D—H⋯A D—HH⋯A DA D—H⋯A
O3—H3O⋯N1i 0.86 (2)2.07 (2)2.920 (3)174 (4)
N1—H1NCg3ii 0.87 (1)2.88 (2)3.705 (3)160 (2)
C11—H11⋯O1iii 0.952.603.280 (3)129

Symmetry codes: (i) ; (ii) ; (iii) .

Hirshfeld surface analysis

The Hirshfeld surfaces calculated for the structure of (I) provide additional insight into the supra­molecular association and was performed as per a recent publication (Wardell et al., 2017 ▸). The appearance of bright-red spots at the hy­droxy-H3O and amine-N1 atoms on the Hirshfeld surfaces mapped over d norm in Fig. 3 ▸ a and b, respectively, indicate the presence of conventional O—H⋯N hydrogen bonding leading to the linear supra­molecular shown in Fig. 2 ▸ a. The donor and acceptor atoms of this inter­action are also evident on the Hirshfeld surface mapped over the calculated electrostatic potential as blue (positive potential) and red regions (negative potential) near the respective atoms in Fig. 4 ▸. The presence of a blue region around the amine-H1N atom, Fig. 4 ▸ a, and a light-red region with a concave surface above the phenyl (C8–C13) ring, Fig. 4 ▸ b, are indicative of the N—H⋯π inter­action, shown to be influential on the packing. The immediate environments about a reference mol­ecule within shape-indexed-mapped Hirshfeld surface highlighting O—H⋯N hydrogen-bonding, weak inter­molecular C—H⋯O contacts and the N—H⋯π inter­action are illustrated in Fig. 5 ▸ a–c, respectively.
Figure 3

Two views of the Hirshfeld surface for (I) mapped over d norm over the range −0.435 to 1.180 au.

Figure 4

Two views of the Hirshfeld surfaces for (I) mapped over the calculated electrostatic potential over the range ±0.116 au. The red and blue regions represent negative and positive electrostatic potentials, respectively.

Figure 5

Views of Hirshfeld surface for a reference mol­ecule in (I) mapped over the shape-index property highlighting: (a) O—H⋯N hydrogen bonds (black dashed lines), (b) C—H⋯O inter­actions (black dashed lines) and (c) N—H⋯ π–π⋯H—N inter­actions as red- and white- dotted lines, respectively.

The overall two-dimensional fingerprint plot, Fig. 6 ▸ a, and those delineated into H⋯H, O⋯H/H⋯O, N⋯H/H⋯N and C⋯H/H⋯C contacts (McKinnon et al., 2007 ▸) are illustrated in Fig. 6 ▸ b–e, respectively; the relative contributions from various contacts to the Hirshfeld surfaces are summarized in Table 2 ▸. It is clear from the fingerprint plot delineated into H⋯H contacts, Fig. 6 ▸ b, that in spite of contributing the maximum, i.e. 50.4%, to the Hirshfeld surface, these contacts do not have a significant influence upon the mol­ecular aggregation as the atoms are separated at distances greater than the sum of their van der Waals radii.
Figure 6

(a) The full two-dimensional fingerprint plots for (I) and fingerprint plots delineated into (b) H⋯H, (c) O⋯H/H⋯O, (d) N⋯H/H⋯H and (e) C⋯H/H⋯C contacts.

Table 2

Percentage contributions of inter-atomic contacts to the Hirshfeld surface for (I)

Contactpercentage contribution
H⋯H50.4
O⋯H/H⋯O25.1
C⋯H/H⋯C18.9
N⋯H/H⋯N3.0
C⋯O/O⋯C1.3
O⋯O1.3
Despite the absence of characteristic faint-red spots expected on the d norm-mapped Hirshfeld surface for (I), Fig. 3 ▸, the two-dimensional fingerprint plot delineated into O⋯H/H⋯O contacts, Fig. 6 ▸ c, highlights the weak inter­molecular C—H⋯O contacts, Fig. 5 ▸ b. The distribution of points in the form of two adjoining cones with the peaks at d e + d i ∼ 2.6 Å confirms the presence of these contacts as well as the short inter-atomic O⋯H/H⋯O contacts listed in Table 3 ▸. A pair of well-separated spikes with the tips at d e + d i  ∼ 2.1 Å in the fingerprint plot delineated into N⋯H/H⋯N contacts, Fig. 6 ▸ d, results from the presence of the O—H⋯N hydrogen bond. In the fingerprint plot delineated into C⋯H/H⋯C contacts, Fig. 6 ▸ e, these contacts appear as the distribution of points having a pair of peaks around d e + d i ∼ 2.8 Å. The short inter-atomic C⋯H/H⋯C contacts involving the amine-HN1, pyranyl-H5 and phenyl-carbon C10, C12 and C13 atoms, Table 3 ▸, arise from the presence of N—H⋯π(phen­yl) inter­actions. Their reciprocal, i.e. π⋯H—N inter­actions, are recognized from similar short inter-atomic contacts involving pyranyl-H7 and phenyl-carbon atoms C9 and C10, Fig. 5 ▸ c and Table 3 ▸. The small contribution of 1.3% from O⋯O and C⋯O/O⋯C contacts exert a negligible influence on the packing.
Table 3

Summary of short inter-atomic contacts (Å) in (I)

Contactdistancesymmetry operation
H1N⋯C122.888 (18)1 − x, − + y, −z
H1N⋯C132.875 (19)1 − x, − + y, −z
H5⋯C102.891 − x, − + y, −z
H7⋯C92.841 − x,  + y, −z
H7⋯C102.801 − x,  + y, −z
H2⋯O22.642 − x,  + y, 1 − z
H3⋯O12.62−1 + x, y, z
C3⋯O13.209 (3)−1 + x, y, z

Database survey

As mentioned in the Chemical context, compound (I) is an aza derivative of the biologically active species (+)-isoaltholactone whereby the ether-oxygen atom of the five-membered ring of the latter has been substituted with a NH group. Indeed, the structure of (+)-isoaltholactone (Colegate et al., 1990 ▸) is the most closely related structure to (I) in the crystallographic literature (Groom et al., 2016 ▸). A structural overlay diagram of (I) and (+)-isoaltholactone is shown in Fig. 7 ▸ from which it can be seen the conformations exhibit a high degree of agreement, the only difference relating to the relative orientations of the terminal phenyl group. The mol­ecular framework of (I) comprising the two fused-rings linked by a Csp 3—Csp 3 single bond is without precedent in the crystallographic literature. However, there are two examples where the link between the five- and six-membered rings is a double bond, namely 3-acetyl-2-methyl­isochromeno[4,3-b]pyrrol-5(1H)-one (Pathak et al., 2011 ▸) and 8-methyl­isochromeno[4,3-b]indol-5(11H)-one (Meng et al., 2014 ▸).
Figure 7

Mol­ecular overlay diagram of (I) and (+)-isoaltholactone shown as red and blue images, respectively.

Synthesis and crystallization

The compound was prepared as described in the literature (Moro, et al., 2011 ▸). Crystals for the present study were obtained by vapour diffusion of hexane into ethyl ether solution of (I).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4 ▸. Carbon-bound H atoms were placed in calculated positions (C—H = 0.95–1.00 Å) and were included in the refinement in the riding-model approximation, with U iso(H) set to 1.2U eq(C). The O- and N-bound H atoms were located from a difference map, but refined with O—H = 0.84±0.01 Å and N—H = 0.88±0.01 Å, and with U iso(H) = 1.5U eq(O) and 1.2U eq(N). As the value of the Flack parameter was ambiguous, the absolute structure is based on that of the starting material employed in the reaction (Moro, et al., 2011 ▸).
Table 4

Experimental details

Crystal data
Chemical formulaC13H13NO3
M r 231.24
Crystal system, space groupMonoclinic, P21
Temperature (K)100
a, b, c (Å)5.9638 (2), 8.4266 (3), 11.0246 (4)
β (°)92.779 (3)
V3)553.39 (3)
Z 2
Radiation typeMo Kα
μ (mm−1)0.10
Crystal size (mm)0.40 × 0.40 × 0.20
 
Data collection
DiffractometerBruker SMART APEXII
Absorption correctionMulti-scan (SADABS; Sheldrick, 1996)
T min, T max 0.914, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections4550, 2377, 2149
R int 0.017
(sin θ/λ)max−1)0.650
 
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S 0.036, 0.094, 1.03
No. of reflections2377
No. of parameters160
No. of restraints3
H-atom treatmentH-atom parameters not refined
Δρmax, Δρmin (e Å−3)0.14, −0.19
Absolute structureFlack x determined using 856 quotients [(I +)−(I )]/[(I +)+(I )] (Parsons et al., 2013)
Absolute structure parameter0.7 (5)

Computer programs: APEX2 and SAINT (Bruker, 2007 ▸), SHELXS97 (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), ORTEP-3 for Windows (Farrugia, 2012 ▸), QMol (Gans & Shalloway, 2001 ▸), DIAMOND (Brandenburg, 2006 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) . DOI: 10.1107/S2056989017005680/hg5487sup1.cif Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989017005680/hg5487Isup2.hkl Click here for additional data file. Supporting information file. DOI: 10.1107/S2056989017005680/hg5487Isup3.cml CCDC reference: 1543983 Additional supporting information: crystallographic information; 3D view; checkCIF report
C13H13NO3F(000) = 244
Mr = 231.24Dx = 1.388 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
a = 5.9638 (2) ÅCell parameters from 2450 reflections
b = 8.4266 (3) Åθ = 2.4–27.3°
c = 11.0246 (4) ŵ = 0.10 mm1
β = 92.779 (3)°T = 100 K
V = 553.39 (3) Å3Block, colourless
Z = 20.40 × 0.40 × 0.20 mm
Bruker SMART APEXII diffractometer2377 independent reflections
Radiation source: sealed tube2149 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.017
φ and ω scansθmax = 27.5°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −6→7
Tmin = 0.914, Tmax = 1.000k = −10→10
4550 measured reflectionsl = −14→14
Refinement on F2H-atom parameters not refined
Least-squares matrix: fullw = 1/[σ2(Fo2) + (0.0534P)2 + 0.049P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.036(Δ/σ)max < 0.001
wR(F2) = 0.094Δρmax = 0.14 e Å3
S = 1.03Δρmin = −0.19 e Å3
2377 reflectionsAbsolute structure: Flack x determined using 856 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
160 parametersAbsolute structure parameter: 0.7 (5)
3 restraints
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.
xyzUiso*/Ueq
O11.1372 (3)0.1225 (4)0.51075 (18)0.0772 (7)
O21.0038 (3)−0.0413 (2)0.37308 (15)0.0519 (5)
O31.0370 (3)0.1267 (2)0.16741 (16)0.0474 (4)
H3O1.171 (3)0.091 (5)0.176 (3)0.071*
N10.4839 (3)−0.0156 (3)0.18328 (16)0.0399 (4)
H1N0.463 (4)−0.1113 (19)0.156 (2)0.048*
C10.9838 (4)0.0886 (4)0.44096 (19)0.0497 (6)
C20.7749 (4)0.1800 (3)0.4292 (2)0.0499 (6)
H20.76920.28170.46610.060*
C30.5947 (4)0.1256 (4)0.3691 (2)0.0452 (5)
H30.46120.18730.36640.054*
C40.5952 (4)−0.0302 (3)0.3053 (2)0.0424 (5)
H40.5202−0.11330.35380.051*
C50.8350 (4)−0.0795 (3)0.2802 (2)0.0427 (5)
H50.8361−0.19710.26830.051*
C60.8844 (3)−0.0009 (3)0.15679 (18)0.0371 (5)
H60.9389−0.08210.09900.044*
C70.6538 (3)0.0636 (3)0.11123 (18)0.0325 (4)
H70.65100.17880.13300.039*
C80.6046 (3)0.0531 (3)−0.02427 (19)0.0343 (4)
C90.3983 (4)0.0059 (3)−0.0742 (2)0.0429 (5)
H90.2824−0.0227−0.02220.051*
C100.3576 (4)−0.0004 (3)−0.1992 (2)0.0483 (6)
H100.2153−0.0342−0.23190.058*
C110.5227 (4)0.0422 (3)−0.2758 (2)0.0495 (6)
H110.49470.0384−0.36140.059*
C120.7296 (4)0.0904 (4)−0.2272 (2)0.0513 (6)
H120.84460.1197−0.27960.062*
C130.7697 (4)0.0962 (3)−0.1027 (2)0.0457 (6)
H130.91220.1302−0.07030.055*
U11U22U33U12U13U23
O10.0479 (11)0.130 (2)0.0521 (10)0.0000 (13)−0.0175 (9)−0.0153 (14)
O20.0411 (9)0.0693 (12)0.0437 (8)0.0104 (8)−0.0133 (7)0.0077 (9)
O30.0286 (7)0.0602 (10)0.0528 (9)−0.0071 (7)−0.0035 (7)0.0029 (9)
N10.0318 (9)0.0502 (11)0.0374 (9)−0.0081 (9)−0.0018 (7)0.0015 (9)
C10.0378 (12)0.0800 (19)0.0307 (10)−0.0039 (12)−0.0044 (9)0.0034 (12)
C20.0434 (13)0.0707 (17)0.0356 (11)0.0002 (12)0.0022 (10)−0.0095 (11)
C30.0333 (11)0.0673 (15)0.0351 (10)0.0030 (11)0.0037 (8)−0.0010 (11)
C40.0341 (11)0.0546 (14)0.0383 (11)−0.0068 (10)−0.0009 (8)0.0079 (11)
C50.0398 (12)0.0440 (12)0.0433 (12)0.0033 (10)−0.0084 (10)0.0047 (10)
C60.0278 (9)0.0451 (12)0.0379 (10)0.0038 (9)−0.0027 (8)−0.0032 (10)
C70.0258 (9)0.0366 (10)0.0348 (10)0.0011 (8)−0.0010 (8)0.0003 (9)
C80.0309 (10)0.0354 (10)0.0363 (10)0.0033 (8)−0.0025 (9)0.0000 (8)
C90.0322 (10)0.0561 (14)0.0400 (11)−0.0028 (10)−0.0014 (9)−0.0019 (11)
C100.0391 (11)0.0620 (15)0.0426 (12)−0.0018 (12)−0.0098 (10)−0.0040 (12)
C110.0535 (14)0.0582 (14)0.0363 (11)0.0033 (12)−0.0036 (11)0.0019 (11)
C120.0468 (13)0.0663 (18)0.0410 (12)−0.0055 (12)0.0039 (10)0.0090 (12)
C130.0373 (12)0.0560 (14)0.0433 (12)−0.0076 (10)−0.0032 (9)0.0050 (11)
O1—C11.201 (3)C5—H51.0000
O2—C11.334 (4)C6—C71.540 (3)
O2—C51.437 (3)C6—H61.0000
O3—C61.409 (3)C7—C81.511 (3)
O3—H3O0.852 (13)C7—H71.0000
N1—C41.476 (3)C8—C91.382 (3)
N1—C71.477 (3)C8—C131.390 (3)
N1—H1N0.869 (13)C9—C101.388 (3)
C1—C21.465 (4)C9—H90.9500
C2—C31.317 (3)C10—C111.376 (4)
C2—H20.9500C10—H100.9500
C3—C41.490 (4)C11—C121.383 (4)
C3—H30.9500C11—H110.9500
C4—C51.527 (3)C12—C131.383 (3)
C4—H41.0000C12—H120.9500
C5—C61.554 (3)C13—H130.9500
C1—O2—C5120.30 (18)C7—C6—C5103.38 (16)
C6—O3—H3O110 (3)O3—C6—H6110.3
C4—N1—C7103.78 (16)C7—C6—H6110.3
C4—N1—H1N107.0 (17)C5—C6—H6110.3
C7—N1—H1N108.7 (18)N1—C7—C8113.57 (17)
O1—C1—O2117.9 (3)N1—C7—C6106.87 (16)
O1—C1—C2123.3 (3)C8—C7—C6115.42 (17)
O2—C1—C2118.7 (2)N1—C7—H7106.8
C3—C2—C1122.1 (3)C8—C7—H7106.8
C3—C2—H2119.0C6—C7—H7106.8
C1—C2—H2119.0C9—C8—C13118.11 (19)
C2—C3—C4121.6 (2)C9—C8—C7122.51 (19)
C2—C3—H3119.2C13—C8—C7119.36 (19)
C4—C3—H3119.2C8—C9—C10121.1 (2)
N1—C4—C3110.2 (2)C8—C9—H9119.5
N1—C4—C5103.95 (18)C10—C9—H9119.5
C3—C4—C5110.40 (19)C11—C10—C9120.3 (2)
N1—C4—H4110.7C11—C10—H10119.9
C3—C4—H4110.7C9—C10—H10119.9
C5—C4—H4110.7C10—C11—C12119.4 (2)
O2—C5—C4116.09 (19)C10—C11—H11120.3
O2—C5—C6111.85 (19)C12—C11—H11120.3
C4—C5—C6105.18 (17)C13—C12—C11120.2 (2)
O2—C5—H5107.8C13—C12—H12119.9
C4—C5—H5107.8C11—C12—H12119.9
C6—C5—H5107.8C12—C13—C8121.0 (2)
O3—C6—C7108.71 (18)C12—C13—H13119.5
O3—C6—C5113.67 (18)C8—C13—H13119.5
C5—O2—C1—O1−174.2 (2)C4—N1—C7—C8164.56 (19)
C5—O2—C1—C27.4 (3)C4—N1—C7—C636.1 (2)
O1—C1—C2—C3−167.4 (3)O3—C6—C7—N1−137.08 (18)
O2—C1—C2—C310.9 (4)C5—C6—C7—N1−16.0 (2)
C1—C2—C3—C4−2.3 (4)O3—C6—C7—C895.6 (2)
C7—N1—C4—C376.7 (2)C5—C6—C7—C8−143.36 (19)
C7—N1—C4—C5−41.6 (2)N1—C7—C8—C913.6 (3)
C2—C3—C4—N1−135.3 (2)C6—C7—C8—C9137.5 (2)
C2—C3—C4—C5−21.0 (3)N1—C7—C8—C13−168.2 (2)
C1—O2—C5—C4−32.2 (3)C6—C7—C8—C13−44.3 (3)
C1—O2—C5—C688.5 (3)C13—C8—C9—C100.8 (4)
N1—C4—C5—O2155.49 (19)C7—C8—C9—C10179.1 (2)
C3—C4—C5—O237.3 (3)C8—C9—C10—C11−0.7 (4)
N1—C4—C5—C631.3 (2)C9—C10—C11—C120.3 (4)
C3—C4—C5—C6−86.9 (2)C10—C11—C12—C13−0.2 (4)
O2—C5—C6—O3−18.5 (3)C11—C12—C13—C80.4 (4)
C4—C5—C6—O3108.4 (2)C9—C8—C13—C12−0.7 (4)
O2—C5—C6—C7−136.12 (18)C7—C8—C13—C12−179.0 (2)
C4—C5—C6—C7−9.3 (2)
D—H···AD—HH···AD···AD—H···A
O3—H3O···N1i0.86 (2)2.07 (2)2.920 (3)174 (4)
N1—H1N···Cg3ii0.87 (1)2.88 (2)3.705 (3)160 (2)
C11—H11···O1iii0.952.603.280 (3)129
  8 in total

1.  Qmol: a program for molecular visualization on Windows-based PCs.

Authors:  J D Gans; D Shalloway
Journal:  J Mol Graph Model       Date:  2001       Impact factor: 2.518

2.  Towards quantitative analysis of intermolecular interactions with Hirshfeld surfaces.

Authors:  Joshua J McKinnon; Dylan Jayatilaka; Mark A Spackman
Journal:  Chem Commun (Camb)       Date:  2007-10-07       Impact factor: 6.222

3.  A short history of SHELX.

Authors:  George M Sheldrick
Journal:  Acta Crystallogr A       Date:  2007-12-21       Impact factor: 2.290

Review 4.  Styryl lactones and their derivatives: biological activities, mechanisms of action and potential leads for drug design.

Authors:  A de Fátima; L V Modolo; L S Conegero; R A Pilli; C V Ferreira; L K Kohn; J E de Carvalho
Journal:  Curr Med Chem       Date:  2006       Impact factor: 4.530

5.  The cytotoxicity of naturally occurring styryl lactones.

Authors:  Ze Tian; Sibao Chen; Yaòu Zhang; Minghui Huang; Lin Shi; Feng Huang; Chichun Fong; Mengsu Yang; Peigen Xiao
Journal:  Phytomedicine       Date:  2005-08-15       Impact factor: 5.340

6.  Crystal structure refinement with SHELXL.

Authors:  George M Sheldrick
Journal:  Acta Crystallogr C Struct Chem       Date:  2015-01-01       Impact factor: 1.172

7.  Use of intensity quotients and differences in absolute structure refinement.

Authors:  Simon Parsons; Howard D Flack; Trixie Wagner
Journal:  Acta Crystallogr B Struct Sci Cryst Eng Mater       Date:  2013-05-17

8.  The Cambridge Structural Database.

Authors:  Colin R Groom; Ian J Bruno; Matthew P Lightfoot; Suzanna C Ward
Journal:  Acta Crystallogr B Struct Sci Cryst Eng Mater       Date:  2016-04-01
  8 in total

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