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ISSN: 2056-9890

(S)-N-Benzyl-2-methyl-1,2,3,4-tetra­hydro­iso­quinoline-3-carboxamide

aSchool of Pharmacy and Pharmacology, University of KwaZulu Natal, Durban 4000, South Africa, and bSchool of Chemistry, University of KwaZulu Natal, Durban 4000, South Africa
*Correspondence e-mail: maguireg@ukzn.ac.za

(Received 12 November 2010; accepted 1 December 2010; online 11 December 2010)

The structure of the title compound, C18H20N2O, at 173 K has hexa­gonal (P61) symmetry. The N-containing six-membered ring assumes a half-chair conformation. In the crystal, inter­molecular N—H⋯O hydrogen bonding via the amide groups cross-link the mol­ecules along the a axis. The absolute configuration was confirmed by 2D NMR studies.

Related literature

The title compound is a precursor to chiral ligands involving a tetra­hydro­isoquinoline backbone. For the application of these ligands as catalysts, see: Chakka et al. (2009[Chakka, S., Andersson, P. G., Govender, T., Kruger, H. G. & Maguire, G. E. M. (2009). Eur. J. Org. Chem. pp. 972-980.]); Peters et al. (2010[Peters, B. K., Chakka, S. K., Naicker, T., Maguire, G. E. M., Kruger, H. G., Andersson, P. G. & Govender, T. (2010). Tetrahedron Asymmetry, 21, 679-687.]); Naicker et al. (2010a[Naicker, T., Petzold, K., Singh, T., Arvidsson, P. I., Kruger, H. G., Maguire, G. E. M. & Govender, T. (2010a). Tetrahedron Asymmetry. In the press. doi: 10.1016/j.tetasy.2010.11.010.]). For related structures, see: Chakka et al. (2010[Chakka, S. K., Govender, T., Kruger, H. G. & Maguire, G. E. M. (2010). Acta Cryst. E66, o1818.]). For a related structure with the same chiral centre and conformation of the six-membered ring, see: Naicker et al. (2010b[Naicker, T., Govender, T., Kruger, H. G. & Maguire, G. E. M. (2010b). Acta Cryst. E66, o638.]).

[Scheme 1]

Experimental

Crystal data
  • C18H20N2O

  • Mr = 280.36

  • Hexagonal, P 61

  • a = 10.1838 (13) Å

  • c = 25.965 (3) Å

  • V = 2332.1 (5) Å3

  • Z = 6

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 173 K

  • 0.22 × 0.12 × 0.03 mm

Data collection
  • Bruker Kappa DUO APEXII diffractometer

  • 18777 measured reflections

  • 1759 independent reflections

  • 1358 reflections with I > 2σ(I)

  • Rint = 0.059

Refinement
  • R[F2 > 2σ(F2)] = 0.036

  • wR(F2) = 0.088

  • S = 1.05

  • 1759 reflections

  • 195 parameters

  • 2 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.14 e Å−3

  • Δρmin = −0.14 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2⋯O1i 0.96 (2) 1.92 (2) 2.852 (3) 165 (3)
Symmetry code: (i) [y, -x+y+1, z-{\script{1\over 6}}].

Data collection: APEX2 (Bruker, 2006[Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2006[Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

The title compound (Fig. 1) is a precursor in the synthesis of novel chiral ligands involving a tetrahydroisoquinoline backbone. Recently, we have reported the application of these ligands as useful catalysts for transfer hydrogenation of prochiral ketones (Chakka et al., 2009), Henry reactions, hydrogenation of olefins (Peters et al. 2010) and Diels-Alder reactions (Naicker et al., 2010a).

Compound 1 was derived from commercially available S-phenyl glycine and formaldehyde. The absolute stereochemistry was confirmed to be S at the C9 position from proton NMR spectroscopy. (Peters et al. 2010).

From the crystal structure it is evident that the N-containing six membered ring assumes a half chair conformation (Fig. 1), in which the 1—N1—C9—C8 bond has a torsion angle of 68.7 (3)°. This observation is similar to analogous structures that we have reported recently (Chakka et al., 2010) and (Naicker et al., 2010b).

The molecule exhibits intermolecular hydrogen bonding, which involves the atom O1 which links the molecules together see Table 1 and Fig. 2.

Related literature top

The title compound is a precursor to novel chiral ligands involving a tetrahydroisoquinoline backbone. For the application of these ligands as catalysts, see: Chakka et al. (2009); Peters et al. (2010); Naicker et al. (2010a). For related structures, see: Chakka et al. (2010). For a related structure with the same chiral centre and conformation of the six-membered ring, see: Naicker et al. (2010b).

Experimental top

(S)-2-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (1.5 g, 7.8 mmol) was dissolved in DMF (15 ml) followed by addition of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) hydrochloride (8.8 mmol), hydroxybenzotriazole (0.81 g, 8.3 mmol), a catalytic amount of 4-dimethylaminopyridine and benzyl amine (8.3 mmol). The reaction mixture was then stirred at room temperature until no more starting material could be detected by TLC analysis (approximately 1 h). The reaction mixture was poured into 30 volumes of chilled water; the mixture was then extracted twice with ethyl acetate. The extracts were combined, washed with 5% HCl (aq) to remove latent EDC urea, dried over anhydrous magnesium sulfate and then concentrated to dryness affording the crude product which was purified by column chromatography.

Melting point 91–95 oC. [α]20D -7.93 (c 0.21 in CHCl3).

IR (neat) nmax: 3281, 2923, 1646, 1548, 1454, 1240, 739, 696 cm-1.

1H NMR (400 MHz, CDCl3) δ = 2.78 (d, 3H), 3.12 (m, 2), 3.52 (t, 1H), 3.66 (m, 3H), 3.78 (d, 1H), 6.99 (d, 1H), 7.19 (m, 3H), 7.30 (m, 6H)

Recrystallization from EtOAc afforded colourless crystals suitable for X-ray analysis.

Refinement top

All hydrogen atoms on carbons were positioned geometrically with C—H distances ranging from 0.95 Å to 1.00 Å and refined as riding on their parent atoms, with Uiso (H) = 1.2 - 1.5 Ueq (C). The position of amine hydrogen H2 was located in the difference electron density maps and refined with simple bond length constraints. The Flack x parameter is -0.5 (15) without merging Friedel pairs, so Friedel pairs were merged at the final refinement.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of compound 1 with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms have been omitted for clarity.
[Figure 2] Fig. 2. Hydrogen bonding interactions between atoms N2—H2···O1.
(S)-N-Benzyl-2-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide top
Crystal data top
C18H20N2ODx = 1.198 Mg m3
Mr = 280.36Melting point: 365 K
Hexagonal, P61Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 61Cell parameters from 18777 reflections
a = 10.1838 (13) Åθ = 2.3–27.2°
c = 25.965 (3) ŵ = 0.08 mm1
V = 2332.1 (5) Å3T = 173 K
Z = 6Needle, colourless
F(000) = 9000.22 × 0.12 × 0.03 mm
Data collection top
Bruker Kappa DUO APEXII
diffractometer
1358 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.059
Graphite monochromatorθmax = 27.2°, θmin = 2.3°
0.5° ϕ scans and ω scansh = 1312
18777 measured reflectionsk = 1213
1759 independent reflectionsl = 3333
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.088 w = 1/[σ2(Fo2) + (0.0377P)2 + 0.3273P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
1759 reflectionsΔρmax = 0.14 e Å3
195 parametersΔρmin = 0.14 e Å3
2 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0033 (7)
Crystal data top
C18H20N2OZ = 6
Mr = 280.36Mo Kα radiation
Hexagonal, P61µ = 0.08 mm1
a = 10.1838 (13) ÅT = 173 K
c = 25.965 (3) Å0.22 × 0.12 × 0.03 mm
V = 2332.1 (5) Å3
Data collection top
Bruker Kappa DUO APEXII
diffractometer
1358 reflections with I > 2σ(I)
18777 measured reflectionsRint = 0.059
1759 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0362 restraints
wR(F2) = 0.088H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.14 e Å3
1759 reflectionsΔρmin = 0.14 e Å3
195 parameters
Special details top

Experimental. Half sphere of data collected using SAINT strategy (Bruker, 2006). Crystal to detector distance = 40 mm; combination of ϕ and ω scans of 0.5°, 30 s per °, 2 iterations.

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
O10.73695 (19)0.77313 (19)0.97396 (7)0.0450 (5)
N10.9118 (2)1.1026 (2)0.98992 (8)0.0385 (5)
N20.7085 (2)0.8382 (2)0.89310 (8)0.0362 (5)
H20.747 (3)0.915 (2)0.8671 (9)0.051 (8)*
C11.0391 (3)1.2586 (3)0.98885 (11)0.0465 (7)
H1A1.04021.30991.02140.056*
H1B1.02411.31390.96020.056*
C21.1898 (3)1.2671 (3)0.98225 (10)0.0406 (6)
C31.3244 (4)1.4003 (3)0.99539 (12)0.0537 (8)
H31.31971.48481.00870.064*
C41.4632 (3)1.4096 (3)0.98919 (13)0.0595 (8)
H41.55351.49990.99840.071*
C51.4714 (3)1.2876 (4)0.96964 (13)0.0581 (8)
H51.56711.29410.96520.070*
C61.3402 (3)1.1566 (3)0.95657 (11)0.0463 (7)
H61.34611.07250.94360.056*
C71.1987 (3)1.1457 (3)0.96216 (10)0.0374 (6)
C81.0561 (3)1.0021 (3)0.94725 (11)0.0378 (6)
H8A1.03560.92250.97300.045*
H8B1.07180.96680.91350.045*
C90.9188 (3)1.0240 (3)0.94379 (10)0.0345 (5)
H90.92831.08590.91260.041*
C100.7785 (3)0.8671 (3)0.93857 (10)0.0343 (5)
C110.5866 (3)0.6863 (3)0.87851 (10)0.0393 (6)
H11A0.51100.69580.85730.047*
H11B0.53490.62880.91000.047*
C120.6459 (3)0.6001 (3)0.84871 (9)0.0373 (6)
C130.7331 (4)0.5489 (4)0.87268 (12)0.0623 (9)
H130.75280.56550.90850.075*
C140.7920 (4)0.4739 (4)0.84516 (14)0.0685 (10)
H140.85230.44020.86220.082*
C150.7643 (4)0.4478 (4)0.79358 (13)0.0615 (9)
H150.80530.39670.77470.074*
C160.6769 (4)0.4962 (4)0.76946 (13)0.0680 (10)
H160.65650.47820.73370.082*
C170.6180 (4)0.5713 (3)0.79703 (12)0.0529 (7)
H170.55680.60370.77980.063*
C180.7705 (3)1.1059 (4)0.99296 (14)0.0573 (8)
H18A0.68461.00190.99350.086*
H18B0.76191.15940.96290.086*
H18C0.77001.15861.02450.086*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0379 (9)0.0402 (10)0.0409 (10)0.0076 (8)0.0062 (8)0.0136 (8)
N10.0387 (12)0.0377 (11)0.0414 (12)0.0208 (10)0.0035 (9)0.0012 (9)
N20.0370 (11)0.0366 (11)0.0349 (11)0.0183 (9)0.0024 (9)0.0071 (9)
C10.0571 (16)0.0354 (14)0.0488 (16)0.0245 (13)0.0015 (13)0.0017 (12)
C20.0453 (14)0.0287 (12)0.0408 (14)0.0133 (11)0.0010 (12)0.0058 (11)
C30.065 (2)0.0303 (14)0.0522 (18)0.0137 (14)0.0029 (14)0.0044 (12)
C40.0422 (16)0.0433 (16)0.065 (2)0.0006 (13)0.0056 (15)0.0107 (15)
C50.0371 (15)0.0565 (18)0.067 (2)0.0128 (14)0.0042 (14)0.0108 (16)
C60.0365 (14)0.0439 (15)0.0532 (17)0.0162 (12)0.0031 (12)0.0094 (13)
C70.0381 (13)0.0290 (12)0.0388 (13)0.0121 (11)0.0011 (11)0.0073 (11)
C80.0336 (12)0.0299 (12)0.0459 (14)0.0130 (11)0.0036 (11)0.0001 (11)
C90.0349 (13)0.0321 (12)0.0340 (12)0.0149 (10)0.0029 (10)0.0071 (10)
C100.0315 (12)0.0360 (13)0.0356 (13)0.0170 (10)0.0005 (10)0.0067 (10)
C110.0295 (13)0.0442 (14)0.0403 (14)0.0156 (11)0.0071 (11)0.0036 (11)
C120.0300 (12)0.0325 (13)0.0375 (14)0.0067 (10)0.0004 (11)0.0021 (11)
C130.073 (2)0.097 (3)0.0420 (17)0.061 (2)0.0073 (15)0.0093 (16)
C140.069 (2)0.089 (3)0.067 (2)0.054 (2)0.0099 (18)0.0217 (19)
C150.0525 (18)0.0532 (18)0.064 (2)0.0151 (15)0.0066 (16)0.0209 (16)
C160.085 (3)0.0545 (19)0.0404 (16)0.0168 (18)0.0052 (17)0.0131 (15)
C170.0631 (19)0.0404 (15)0.0440 (16)0.0174 (14)0.0140 (14)0.0050 (13)
C180.0526 (17)0.067 (2)0.065 (2)0.0395 (16)0.0052 (15)0.0012 (16)
Geometric parameters (Å, º) top
O1—C101.239 (3)C8—H8A0.9900
N1—C181.458 (3)C8—H8B0.9900
N1—C91.462 (3)C9—C101.527 (3)
N1—C11.465 (3)C9—H91.0000
N2—C101.334 (3)C11—C121.504 (4)
N2—C111.469 (3)C11—H11A0.9900
N2—H20.957 (10)C11—H11B0.9900
C1—C21.503 (4)C12—C171.373 (4)
C1—H1A0.9900C12—C131.383 (4)
C1—H1B0.9900C13—C141.383 (4)
C2—C71.386 (4)C13—H130.9500
C2—C31.406 (4)C14—C151.367 (5)
C3—C41.378 (4)C14—H140.9500
C3—H30.9500C15—C161.365 (5)
C4—C51.382 (5)C15—H150.9500
C4—H40.9500C16—C171.385 (5)
C5—C61.377 (4)C16—H160.9500
C5—H50.9500C17—H170.9500
C6—C71.396 (4)C18—H18A0.9800
C6—H60.9500C18—H18B0.9800
C7—C81.508 (4)C18—H18C0.9800
C8—C91.524 (3)
C18—N1—C9112.1 (2)C8—C9—C10107.39 (19)
C18—N1—C1109.0 (2)N1—C9—H9109.5
C9—N1—C1108.61 (19)C8—C9—H9109.5
C10—N2—C11122.5 (2)C10—C9—H9109.5
C10—N2—H2119.4 (18)O1—C10—N2123.2 (2)
C11—N2—H2117.6 (18)O1—C10—C9121.5 (2)
N1—C1—C2112.9 (2)N2—C10—C9115.3 (2)
N1—C1—H1A109.0N2—C11—C12111.9 (2)
C2—C1—H1A109.0N2—C11—H11A109.2
N1—C1—H1B109.0C12—C11—H11A109.2
C2—C1—H1B109.0N2—C11—H11B109.2
H1A—C1—H1B107.8C12—C11—H11B109.2
C7—C2—C3119.0 (3)H11A—C11—H11B107.9
C7—C2—C1120.8 (2)C17—C12—C13117.6 (3)
C3—C2—C1120.2 (3)C17—C12—C11121.8 (3)
C4—C3—C2120.6 (3)C13—C12—C11120.6 (2)
C4—C3—H3119.7C12—C13—C14120.9 (3)
C2—C3—H3119.7C12—C13—H13119.5
C3—C4—C5120.1 (3)C14—C13—H13119.5
C3—C4—H4119.9C15—C14—C13120.6 (3)
C5—C4—H4119.9C15—C14—H14119.7
C6—C5—C4119.7 (3)C13—C14—H14119.7
C6—C5—H5120.2C16—C15—C14119.2 (3)
C4—C5—H5120.2C16—C15—H15120.4
C5—C6—C7121.0 (3)C14—C15—H15120.4
C5—C6—H6119.5C15—C16—C17120.2 (3)
C7—C6—H6119.5C15—C16—H16119.9
C2—C7—C6119.6 (2)C17—C16—H16119.9
C2—C7—C8120.0 (2)C12—C17—C16121.5 (3)
C6—C7—C8120.4 (2)C12—C17—H17119.3
C7—C8—C9112.5 (2)C16—C17—H17119.3
C7—C8—H8A109.1N1—C18—H18A109.5
C9—C8—H8A109.1N1—C18—H18B109.5
C7—C8—H8B109.1H18A—C18—H18B109.5
C9—C8—H8B109.1N1—C18—H18C109.5
H8A—C8—H8B107.8H18A—C18—H18C109.5
N1—C9—C8109.34 (19)H18B—C18—H18C109.5
N1—C9—C10111.7 (2)
C18—N1—C1—C2176.3 (2)C1—N1—C9—C10172.63 (19)
C9—N1—C1—C253.9 (3)C7—C8—C9—N148.2 (3)
N1—C1—C2—C720.3 (4)C7—C8—C9—C10169.6 (2)
N1—C1—C2—C3161.2 (2)C11—N2—C10—O17.5 (4)
C7—C2—C3—C41.0 (4)C11—N2—C10—C9170.4 (2)
C1—C2—C3—C4179.6 (3)N1—C9—C10—O153.7 (3)
C2—C3—C4—C50.4 (5)C8—C9—C10—O166.2 (3)
C3—C4—C5—C60.2 (5)N1—C9—C10—N2128.3 (2)
C4—C5—C6—C70.8 (4)C8—C9—C10—N2111.8 (2)
C3—C2—C7—C61.6 (4)C10—N2—C11—C1294.2 (3)
C1—C2—C7—C6179.9 (2)N2—C11—C12—C17109.0 (3)
C3—C2—C7—C8179.4 (2)N2—C11—C12—C1370.0 (3)
C1—C2—C7—C80.8 (4)C17—C12—C13—C141.2 (5)
C5—C6—C7—C21.5 (4)C11—C12—C13—C14177.9 (3)
C5—C6—C7—C8179.4 (3)C12—C13—C14—C150.4 (6)
C2—C7—C8—C914.7 (3)C13—C14—C15—C160.3 (5)
C6—C7—C8—C9166.2 (2)C14—C15—C16—C170.3 (5)
C18—N1—C9—C8170.9 (2)C13—C12—C17—C161.1 (4)
C1—N1—C9—C868.7 (2)C11—C12—C17—C16177.9 (3)
C18—N1—C9—C1052.2 (3)C15—C16—C17—C120.4 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O1i0.96 (2)1.92 (2)2.852 (3)165 (3)
Symmetry code: (i) y, x+y+1, z1/6.

Experimental details

Crystal data
Chemical formulaC18H20N2O
Mr280.36
Crystal system, space groupHexagonal, P61
Temperature (K)173
a, c (Å)10.1838 (13), 25.965 (3)
V3)2332.1 (5)
Z6
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.22 × 0.12 × 0.03
Data collection
DiffractometerBruker Kappa DUO APEXII
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
18777, 1759, 1358
Rint0.059
(sin θ/λ)max1)0.642
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.088, 1.05
No. of reflections1759
No. of parameters195
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.14, 0.14

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O1i0.96 (2)1.92 (2)2.852 (3)165 (3)
Symmetry code: (i) y, x+y+1, z1/6.
 

Acknowledgements

The authors wish to thank Dr Hong Su of the Chemistry Department of the University of Cape Town for her assistance with the crystallographic data collection.

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