Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Previous article
Next article
Previous article
Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Next article

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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 1| January 2008| Page o266
https://doi.org/10.1107/S1600536807066056

(11aS)-8-Hydr­­oxy-7-meth­­oxy-2,3,5,10,11,11a-hexa­hydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine-3,11-dione

Dong-Mei Zhao,a Chao Ma,a Yu Sha,a Jing-Hong Liua and Mao-Sheng Chenga*

aSchool of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Mail Box 40, 103 Wenhua Road, Shenhe District, Shenyang 110016, People's Republic of China
*Correspondence e-mail: mscheng@syphu.edu.cn

(Received 4 December 2007; accepted 7 December 2007; online 12 December 2007)

The title chiral compound, C13H14N2O4, was prepared by an intra­cyclization reaction of methyl (S)-1-(4-hydr­oxy-5-meth­oxy-2-nitro­benz­yl)-5-oxopyrrolidine-2-carboxyl­ate in the presence of ethanol and iron. The five-membered substituted pyrrole ring adopts an approximate envelope conformation, while the seven-membered substituted diazepine ring displays a twist-boat conformation. Inter­molecular O—H⋯O and N—H⋯O hydrogen bonding helps to stabilize the crystal structure.

Related literature

For general background, see: Bose et al. (1992[Bose, D. S., Jones, G. B. & Thurston, D. E. (1992). Tetrahedron, 48, 751-758.]); Hu et al. (2001[Hu, W.-P., Wang, J.-J., Lin, F.-L., Lin, Y.-C., Lin, S.-R. & Hsu, M.-H. (2001). J. Org. Chem. 66, 2881-2883.]); Kamal et al. (2002[Kamal, A., Rao, M. V., Laxman, N., Ramesh, G. & Reddy, G. S. K. (2002). Curr. Med. Chem. Anticancer Agents, 2, 215-254.]); Thurston & Bose (1994[Thurston, D. E. & Bose, D. S. (1994). Chem. Rev. 94, 433-465.]). For a related structure, see: Cheng et al. (2007[Cheng, M.-S., Ma, C., Liu, J.-H., Sha, Y. & Wang, Q.-H. (2007). Acta Cryst. E63, o4605.]).

[Scheme 1]

Experimental

Crystal data

  • C13H14N2O4

  • Mr = 262.26

  • Monoclinic, P 21

  • a = 6.3819 (7) Å

  • b = 9.3139 (10) Å

  • c = 10.3673 (11) Å

  • β = 103.621 (1)°

  • V = 598.90 (11) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.11 mm−1

  • T = 187 (2) K

  • 0.48 × 0.26 × 0.15 mm
Data collection

  • Bruker SMART APEX CCD area-detector diffractometer

  • Absorption correction: none

  • 3169 measured reflections

  • 1168 independent reflections

  • 1149 reflections with I > 2σ(I)

  • Rint = 0.013
Refinement

  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.074

  • S = 1.12

  • 1168 reflections

  • 174 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.14 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
O1—H1⋯O4i 0.84 1.95 2.707 (2) 150
N1—H1A⋯O1ii 0.97 2.11 3.023 (2) 157
Symmetry codes: (i) x, y-1, z; (ii) [-x-1, y+{\script{1\over 2}}, -z+1].

Data collection: SMART (Bruker, 1997[Bruker (1997). SMART. Version 5.622. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: SHELXTL-Plus (Siemens, 1990[Siemens (1990). SHELXTL-Plus. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536807066056/xu2391sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807066056/xu2391Isup2.hkl

checkCIF report


Comment top

Pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are a group of potent, naturally occurring antitumor antibiotics produced by Streptomyces species (Kamal et al., 2002; Thurston & Bose, 1994). Naturally occurring Pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) have attracted the attention of many researchers largely because of the potent anticancer activity exhibited in most of the compounds with this ring system (Hu et al., 2001; Bose et al., 1992). As PBDs compounds are of great pharmaceutical importance, we determined the title chiral compound's crystal structure. The molecular is shown in Fig. 1 and the bond lengths and angles are within normal ranges. PBD ring involes in a twisted conformation, similar to a related structure (Cheng et al., 2007). The seven-membered ring C5—C4—C9—N2—C10—C8—N1 (substituted diazepine) is far from planar, and its shape approximates to a twist boat. In this description applied to the title compound (Fig. 1), atoms C8, C9, N1 and N2 form the bottom of the boat (deviation from the mean N1/C9/N2/C8 plane = 0.125 (2) Å), C10 the prow, and C4 and C5 the stern [deviations from the C8/C9/N1/N2 mean plane = 0.567, 0.885, 0.948 Å, respectively]. The bond length of the carbonyl groups C8=O4 and C13=O3 of 1.228 (2) and 1.225 (3) Å, respectively, are somewhat longer than typical carbonyl bonds. This may be due to the fact that atoms O3 and O4 participate in intermolecular van der Waals forces. The five-membered ring N2—C10—C11—C12—C13 (substituted pyrrole) is non-planar and adopts nearly envelope conformation (deviation from the mean C10/N2/C13/C12 plane = 0.021 (5) Å). The C11 atom is located above the plane [deviations from the C10/N2/C13/C12 mean plane = 0.449 Å]. Atom C10 of the title molecule is chiral: S configuration was assigned to this atom based on the known chirality of the equivalent atom in the starting material. In the crystal structure, intermolecular O—H···O and N—H···O hydrogen bonds link the molecules together (Table 1) and help to stabilize the structure.

Related literature top

For general background, see: Bose et al. (1992); Hu et al. (2001); Kamal et al. (2002); Thurston & Bose (1994). For a related structure, see: Cheng et al. (2007).

Experimental top

(S)-1-(4-Hydroxy-5-mythoxy-2-nitrobenzyl)-5-oxopyrrolidine-2-carboxylic acid methyl ester (8.10 g, 25 mmol) was dissolved in ethanol (150 ml). Fe (3.36 g, 60 mmol) was added and the solution was heated to reflux for 30 min. The mixture was filtered and the filtrate was concentrated under vacuum. The pure product was obtained through silica gel chromatography (eluant: petroleum ether/ethyl acetate, 2:1). Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a dilute solution of the title compound in ethyl acetate at room temperature.

Refinement top

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with N—H = 0.97 Å, O—H = 0.84 Å, and C—H = 0.95, 0.99, 0.98 and 1.00 Å for phenyl, methylene, methyl and tertiary H atoms, respectively, with Uiso(H) = xUeq(C,N,O), where x = 1.5 for methyl H and hydroxyl H, and x = 1.2 for all other H atoms. Based on known chirality of the equivalent atom in the starting material, the S chirality at C10 was assigned. Friedels pairs were merged.

Structure description top

Pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are a group of potent, naturally occurring antitumor antibiotics produced by Streptomyces species (Kamal et al., 2002; Thurston & Bose, 1994). Naturally occurring Pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) have attracted the attention of many researchers largely because of the potent anticancer activity exhibited in most of the compounds with this ring system (Hu et al., 2001; Bose et al., 1992). As PBDs compounds are of great pharmaceutical importance, we determined the title chiral compound's crystal structure. The molecular is shown in Fig. 1 and the bond lengths and angles are within normal ranges. PBD ring involes in a twisted conformation, similar to a related structure (Cheng et al., 2007). The seven-membered ring C5—C4—C9—N2—C10—C8—N1 (substituted diazepine) is far from planar, and its shape approximates to a twist boat. In this description applied to the title compound (Fig. 1), atoms C8, C9, N1 and N2 form the bottom of the boat (deviation from the mean N1/C9/N2/C8 plane = 0.125 (2) Å), C10 the prow, and C4 and C5 the stern [deviations from the C8/C9/N1/N2 mean plane = 0.567, 0.885, 0.948 Å, respectively]. The bond length of the carbonyl groups C8=O4 and C13=O3 of 1.228 (2) and 1.225 (3) Å, respectively, are somewhat longer than typical carbonyl bonds. This may be due to the fact that atoms O3 and O4 participate in intermolecular van der Waals forces. The five-membered ring N2—C10—C11—C12—C13 (substituted pyrrole) is non-planar and adopts nearly envelope conformation (deviation from the mean C10/N2/C13/C12 plane = 0.021 (5) Å). The C11 atom is located above the plane [deviations from the C10/N2/C13/C12 mean plane = 0.449 Å]. Atom C10 of the title molecule is chiral: S configuration was assigned to this atom based on the known chirality of the equivalent atom in the starting material. In the crystal structure, intermolecular O—H···O and N—H···O hydrogen bonds link the molecules together (Table 1) and help to stabilize the structure.

For general background, see: Bose et al. (1992); Hu et al. (2001); Kamal et al. (2002); Thurston & Bose (1994). For a related structure, see: Cheng et al. (2007).

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Siemens, 1990); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
(11aS)-8-Hydroxy-7-methoxy-2,3,5,10,11,11a-hexahydro-1H- pyrrolo[2,1-c][1,4]benzodiazepine-3,11-dione top
Crystal data top
C13H14N2O4F(000) = 276
Mr = 262.26Dx = 1.454 Mg m−3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 2332 reflections
a = 6.3819 (7) Åθ = 3.0–25.3°
b = 9.3139 (10) ŵ = 0.11 mm−1
c = 10.3673 (11) ÅT = 187 K
β = 103.621 (1)°Block, colorless
V = 598.90 (11) Å30.48 × 0.26 × 0.15 mm
Z = 2
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		1149 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.013
Graphite monochromatorθmax = 25.3°, θmin = 3.0°
φ and ω scansh = −7→7
3169 measured reflectionsk = −5→11
1168 independent reflectionsl = −12→11
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.074H-atom parameters constrained
S = 1.12 w = 1/[σ2(Fo2) + (0.0425P)2 + 0.0991P]
where P = (Fo2 + 2Fc2)/3
1168 reflections(Δ/σ)max = 0.004
174 parametersΔρmax = 0.14 e Å−3
1 restraintΔρmin = −0.19 e Å−3
Crystal data top
C13H14N2O4V = 598.90 (11) Å3
Mr = 262.26Z = 2
Monoclinic, P21Mo Kα radiation
a = 6.3819 (7) ŵ = 0.11 mm−1
b = 9.3139 (10) ÅT = 187 K
c = 10.3673 (11) Å0.48 × 0.26 × 0.15 mm
β = 103.621 (1)°
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		1149 reflections with I > 2σ(I)
3169 measured reflectionsRint = 0.013
1168 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0301 restraint
wR(F2) = 0.074H-atom parameters constrained
S = 1.12Δρmax = 0.14 e Å−3
1168 reflectionsΔρmin = −0.19 e Å−3
174 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
C1−0.1968 (3)0.3136 (2)0.6150 (2)0.0254 (4)
C20.0218 (3)0.2900 (2)0.6730 (2)0.0283 (5)
C30.1550 (3)0.4061 (3)0.7152 (2)0.0290 (5)
H30.30260.39050.75660.035*
C40.0751 (3)0.5463 (3)0.6978 (2)0.0275 (5)
C5−0.1437 (3)0.5676 (2)0.6429 (2)0.0263 (4)
C6−0.2799 (4)0.4511 (3)0.6011 (2)0.0280 (5)
H6−0.42890.46620.56320.034*
C70.3005 (4)0.1165 (3)0.7439 (3)0.0375 (5)
H7A0.33030.14470.83750.056*
H7B0.39620.16950.69950.056*
H7C0.32530.01320.73740.056*
C8−0.1959 (3)0.8199 (2)0.7104 (2)0.0281 (5)
C90.2252 (3)0.6725 (2)0.7329 (2)0.0304 (5)
H9A0.37510.63690.76200.037*
H9B0.21590.73220.65280.037*
C10−0.0465 (3)0.7914 (3)0.8459 (2)0.0280 (5)
H10−0.10280.70760.88780.034*
C11−0.0166 (3)0.9189 (3)0.9420 (2)0.0360 (5)
H11A−0.12530.91720.99620.043*
H11B−0.02771.01120.89350.043*
C120.2116 (4)0.8965 (3)1.0287 (2)0.0402 (6)
H12A0.28420.98971.05400.048*
H12B0.20730.84251.11030.048*
C130.3266 (3)0.8111 (3)0.9419 (2)0.0310 (5)
N1−0.2336 (3)0.7085 (2)0.62395 (18)0.0314 (4)
H1A−0.35080.71920.54580.038*
N20.1759 (3)0.76080 (19)0.83733 (17)0.0267 (4)
O1−0.3329 (2)0.20085 (17)0.57207 (15)0.0316 (4)
H1−0.27290.12380.60290.047*
O20.0812 (2)0.14895 (17)0.68141 (17)0.0352 (4)
O30.5206 (2)0.7896 (2)0.96020 (16)0.0416 (4)
O4−0.2877 (3)0.93534 (18)0.68144 (17)0.0373 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0268 (10)0.0274 (11)0.0211 (9)−0.0026 (9)0.0038 (8)−0.0001 (9)
C20.0280 (11)0.0297 (11)0.0279 (11)0.0021 (9)0.0078 (8)0.0001 (9)
C30.0229 (10)0.0323 (12)0.0309 (11)0.0032 (9)0.0047 (8)−0.0027 (10)
C40.0264 (10)0.0303 (11)0.0253 (10)−0.0007 (9)0.0055 (8)−0.0016 (9)
C50.0284 (10)0.0255 (11)0.0228 (9)0.0015 (9)0.0017 (8)0.0005 (9)
C60.0255 (10)0.0311 (12)0.0247 (10)−0.0005 (9)0.0003 (8)0.0023 (9)
C70.0272 (11)0.0336 (12)0.0514 (14)0.0057 (9)0.0092 (9)0.0039 (11)
C80.0219 (9)0.0255 (11)0.0353 (11)−0.0025 (9)0.0036 (8)0.0026 (10)
C90.0271 (10)0.0322 (12)0.0320 (11)−0.0021 (9)0.0070 (9)−0.0034 (9)
C100.0236 (10)0.0306 (11)0.0296 (11)−0.0027 (9)0.0059 (8)0.0006 (9)
C110.0305 (11)0.0423 (14)0.0357 (11)−0.0042 (11)0.0086 (9)−0.0097 (11)
C120.0354 (12)0.0521 (16)0.0309 (11)−0.0078 (11)0.0035 (9)−0.0089 (11)
C130.0272 (10)0.0333 (12)0.0295 (10)−0.0055 (9)0.0010 (8)0.0034 (10)
N10.0294 (9)0.0277 (10)0.0304 (9)0.0014 (9)−0.0066 (7)0.0029 (9)
N20.0216 (8)0.0298 (10)0.0273 (9)−0.0013 (7)0.0027 (7)−0.0013 (7)
O10.0300 (8)0.0249 (8)0.0350 (8)−0.0020 (7)−0.0019 (6)0.0021 (7)
O20.0277 (8)0.0272 (9)0.0477 (10)0.0039 (7)0.0029 (7)−0.0019 (7)
O30.0246 (8)0.0513 (11)0.0437 (10)−0.0034 (8)−0.0021 (7)−0.0010 (9)
O40.0328 (9)0.0254 (8)0.0482 (9)0.0019 (7)−0.0013 (7)0.0036 (7)
Geometric parameters (Å, º) top
C1—O11.369 (3)C8—C101.524 (3)
C1—C61.381 (3)C9—N21.452 (3)
C1—C21.400 (3)C9—H9A0.9900
C2—O21.364 (3)C9—H9B0.9900
C2—C31.382 (3)C10—N21.471 (3)
C3—C41.398 (3)C10—C111.532 (3)
C3—H30.9500C10—H101.0000
C4—C51.392 (3)C11—C121.535 (3)
C4—C91.506 (3)C11—H11A0.9900
C5—C61.394 (3)C11—H11B0.9900
C5—N11.427 (3)C12—C131.514 (3)
C6—H60.9500C12—H12A0.9900
C7—O21.429 (3)C12—H12B0.9900
C7—H7A0.9800C13—O31.224 (3)
C7—H7B0.9800C13—N21.353 (3)
C7—H7C0.9800N1—H1A0.9699
C8—O41.228 (3)O1—H10.8400
C8—N11.355 (3)
O1—C1—C6118.58 (18)C4—C9—H9B109.1
O1—C1—C2120.7 (2)H9A—C9—H9B107.8
C6—C1—C2120.7 (2)N2—C10—C8112.39 (17)
O2—C2—C3126.32 (19)N2—C10—C11102.46 (16)
O2—C2—C1114.37 (19)C8—C10—C11114.80 (19)
C3—C2—C1119.3 (2)N2—C10—H10109.0
C2—C3—C4120.79 (18)C8—C10—H10109.0
C2—C3—H3119.6C11—C10—H10109.0
C4—C3—H3119.6C10—C11—C12103.35 (19)
C5—C4—C3119.1 (2)C10—C11—H11A111.1
C5—C4—C9120.5 (2)C12—C11—H11A111.1
C3—C4—C9120.41 (19)C10—C11—H11B111.1
C6—C5—C4120.5 (2)C12—C11—H11B111.1
C6—C5—N1118.15 (18)H11A—C11—H11B109.1
C4—C5—N1121.28 (19)C13—C12—C11104.43 (18)
C1—C6—C5119.54 (19)C13—C12—H12A110.9
C1—C6—H6120.2C11—C12—H12A110.9
C5—C6—H6120.2C13—C12—H12B110.9
O2—C7—H7A109.5C11—C12—H12B110.9
O2—C7—H7B109.5H12A—C12—H12B108.9
H7A—C7—H7B109.5O3—C13—N2124.7 (2)
O2—C7—H7C109.5O3—C13—C12127.5 (2)
H7A—C7—H7C109.5N2—C13—C12107.80 (18)
H7B—C7—H7C109.5C8—N1—C5127.59 (17)
O4—C8—N1120.58 (19)C8—N1—H1A117.1
O4—C8—C10122.5 (2)C5—N1—H1A114.5
N1—C8—C10116.85 (19)C13—N2—C9123.76 (18)
N2—C9—C4112.66 (17)C13—N2—C10113.48 (18)
N2—C9—H9A109.1C9—N2—C10122.48 (16)
C4—C9—H9A109.1C1—O1—H1109.5
N2—C9—H9B109.1C2—O2—C7117.41 (18)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O4i0.841.952.707 (2)150
N1—H1A···O1ii0.972.113.023 (2)157.2
Symmetry codes: (i) x, y−1, z; (ii) −x−1, y+1/2, −z+1.

Experimental details

Crystal data
Chemical formulaC13H14N2O4
Mr262.26
Crystal system, space groupMonoclinic, P21
Temperature (K)187
a, b, c (Å)6.3819 (7), 9.3139 (10), 10.3673 (11)
β (°) 103.621 (1)
V (Å3)598.90 (11)
Z2
Radiation typeMo Kα
µ (mm−1)0.11
Crystal size (mm)0.48 × 0.26 × 0.15
Data collection
DiffractometerBruker SMART APEX CCD area-detector
Absorption correction–
No. of measured, independent and
observed [I > 2σ(I)] reflections		3169, 1168, 1149
Rint0.013
(sin θ/λ)max (Å−1)0.602
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.074, 1.12
No. of reflections1168
No. of parameters174
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.14, −0.19

Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL-Plus (Siemens, 1990).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O4i0.841.952.707 (2)150.0
N1—H1A···O1ii0.972.113.023 (2)157.2
Symmetry codes: (i) x, y−1, z; (ii) −x−1, y+1/2, −z+1.
 

References

First citationBose, D. S., Jones, G. B. & Thurston, D. E. (1992). Tetrahedron, 48, 751–758.  CrossRef Google Scholar
 First citationBruker (1997). SMART. Version 5.622. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationBruker (1999). SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationCheng, M.-S., Ma, C., Liu, J.-H., Sha, Y. & Wang, Q.-H. (2007). Acta Cryst. E63, o4605.  Web of Science CSD CrossRef IUCr Journals Google Scholar
 First citationHu, W.-P., Wang, J.-J., Lin, F.-L., Lin, Y.-C., Lin, S.-R. & Hsu, M.-H. (2001). J. Org. Chem. 66, 2881–2883.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationKamal, A., Rao, M. V., Laxman, N., Ramesh, G. & Reddy, G. S. K. (2002). Curr. Med. Chem. Anticancer Agents, 2, 215–254.  CrossRef PubMed CAS Google Scholar
 First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.  Google Scholar
 First citationSiemens (1990). SHELXTL-Plus. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationThurston, D. E. & Bose, D. S. (1994). Chem. Rev. 94, 433–465.  CrossRef CAS Web of Science Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 1| January 2008| Page o266
https://doi.org/10.1107/S1600536807066056
Follow Acta Cryst. E
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS