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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 5| May 2010| Page o1072

Cyclo­hexane-1-spiro-2′-imidazolidine-5′-spiro-1′′-cyclo­hexan-4′-one

aCentre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India, bDepartment of Chemistry, Government Arts College (Autonomous), Coimbatore 641 018, India, and cDepartment of Chemistry, Queen Mary's College (Autonomous), Chennai 600 004, India
*Correspondence e-mail: mnpsy2004@yahoo.com

(Received 26 February 2010; accepted 2 April 2010; online 14 April 2010)

In the title compound, C13H22N2O, the central imidazolidine ring is in an envelope conformation and the two cyclo­hexane rings adopt chair conformations. In the crystal structure, the mol­ecules are linked into centrosymmetric R22(8) dimers by pairs of N—H⋯O hydrogen bonds.

Related literature

For general background to imidazolidine derivatives, see: Tsao et al. (1991[Tsao, T. C., Williams, D. E., Worley, C. G. & Worley, S. D. (1991). Biotechnol. Prog. 7, 60-66.]); Wang et al. (1995[Wang, W., Liang, T. C., Zheng, M. & Gao, X. (1995). Tetrahedron Lett. 36, 1181-1184.]). For bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brummer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]). For hydrogen-bond motifs, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]). For ring conformational analysis, see: Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]); Nardelli (1995[Nardelli, M. (1995). J. Appl. Cryst. 28, 659.]).

[Scheme 1]

Experimental

Crystal data
  • C13H22N2O

  • Mr = 222.33

  • Triclinic, [P \overline 1]

  • a = 5.8270 (8) Å

  • b = 10.1703 (5) Å

  • c = 10.6651 (4) Å

  • α = 86.103 (2)°

  • β = 81.331 (3)°

  • γ = 89.720 (3)°

  • V = 623.36 (9) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 293 K

  • 0.20 × 0.15 × 0.15 mm

Data collection
  • Bruker Kappa APEXII area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2001[Sheldrick, G. M. (2001). SADABS. University of Göttingen, Germany.]) Tmin = 0.985, Tmax = 0.989

  • 11727 measured reflections

  • 2311 independent reflections

  • 2023 reflections with I > 2σ(I)

  • Rint = 0.020

Refinement
  • R[F2 > 2σ(F2)] = 0.039

  • wR(F2) = 0.104

  • S = 1.04

  • 2311 reflections

  • 153 parameters

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

  • Δρmax = 0.22 e Å−3

  • Δρmin = −0.16 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N3—H3⋯O1i 0.87 (2) 2.02 (2) 2.8821 (14) 172 (1)
Symmetry code: (i) -x+1, -y+1, -z+1.

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2004[Bruker (2004). 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: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995[Nardelli, M. (1995). J. Appl. Cryst. 28, 659.]).

Supporting information


Comment top

Imidazolidines occupy a unique position among the five-membered heterocycles and are highly used in synthetic as well as mechanistic organic chemistry and biochemistry (Tsao et al., 1991). Imidazolidine derivatives are important intermediates and building blocks in the construction of various biologically active compounds (Wang et al., 1995).

In the title molecule (Fig. 1), the five-membered imidazolidine ring is transfused with two cyclohexane rings. The bond lengths are comparable to the reported values (Allen et al., 1987). The imidazolidine ring adopts an envelope conformation, with flap atom N1 deviating by 0.198 (2) Å from the C2/N3/C4/C5 plane. The asymmetry parameters for the imidazolidine ring shows that a mirror plane is passing through the atom N1 [ΔCs = 2.7 (1)] (Nardelli, 1995); the puckering parameters [q2 = 0.128 (1) Å and ϕ(2) = 187.8 (5)°] (Cremer & Pople, 1975) also support the above fact. The sum of the bond angles around N1 (326.6°) shows sp3 hybridization and atom N3 (359.6°) is in accordance with sp2 hybridization. The two cyclohexane rings adopt chair conformations.

In the crystal, molecules are linked into centrosymmetric R22(8) (Bernstein et al., 1995) dimers by pairs of N—H···O hydrogen bonds (Table 1).

Related literature top

For general background to imidazolidine derivatives, see: Tsao et al. (1991); Wang et al. (1995). For bond-length data, see: Allen et al. (1987). For hydrogen-bond motifs, see: Bernstein et al. (1995). For ring conformational analysis, see: Cremer & Pople (1975); Nardelli (1995).

Experimental top

Potassium cyanide (20 mmol), ammonium chloride (20 mmol) and aqueous ammonium sulfide (30 ml) were dissolved in water (50 ml). Cyclohexanone (40 mmol) was slowly added into the above reaction mixture and stirred for 8 h at 333 K. The precipitated cyclohexan-1-spiro-2'-(imidazolidin-4'-thione)-5'-spiro-1''-cyclohexane was filtered. An ice-cold solution of the above imidazolidin-4-thione (5 mm0l) in glacial acetic acid (5 ml) was treated with hydrogen peroxide (30%, 5 ml) and kept at room temperature for 24 h. The reaction mixture was poured into crushed ice and extracted with ether (40 ml). Evaporation of ether yielded the title compound which was recrystallized by slow evaporation of a water–acetone (20:2) solution.

Refinement top

N-bound H atoms were located in a difference map and refined freely. C-bound H atoms were positioned geometrically (C—H = 0.97 Å) and allowed to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PARST (Nardelli, 1995).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. H atoms are shown as circles with arbitrary radii.
[Figure 2] Fig. 2. Crystal packing of the title compound. Dashed line indicate hydrogen bonds. H atoms not involved in hydrogen bonding (dashed lines) have been omitted for clarity.
Cyclohexane-1-spiro-2'-imidazolidine-5'-spiro-1''-cyclohexan-4'-one top
Crystal data top
C13H22N2OZ = 2
Mr = 222.33F(000) = 244
Triclinic, P1Dx = 1.184 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 5.8270 (8) ÅCell parameters from 2023 reflections
b = 10.1703 (5) Åθ = 2.7–25.5°
c = 10.6651 (4) ŵ = 0.08 mm1
α = 86.103 (2)°T = 293 K
β = 81.331 (3)°Block, colourless
γ = 89.720 (3)°0.20 × 0.15 × 0.15 mm
V = 623.36 (9) Å3
Data collection top
Bruker Kappa APEXII area-detector
diffractometer
2311 independent reflections
Radiation source: fine-focus sealed tube2023 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.020
ω scansθmax = 25.5°, θmin = 2.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2001)
h = 77
Tmin = 0.985, Tmax = 0.989k = 1212
11727 measured reflectionsl = 1212
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)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.104H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0492P)2 + 0.1487P]
where P = (Fo2 + 2Fc2)/3
2311 reflections(Δ/σ)max = 0.001
153 parametersΔρmax = 0.22 e Å3
0 restraintsΔρmin = 0.16 e Å3
Crystal data top
C13H22N2Oγ = 89.720 (3)°
Mr = 222.33V = 623.36 (9) Å3
Triclinic, P1Z = 2
a = 5.8270 (8) ÅMo Kα radiation
b = 10.1703 (5) ŵ = 0.08 mm1
c = 10.6651 (4) ÅT = 293 K
α = 86.103 (2)°0.20 × 0.15 × 0.15 mm
β = 81.331 (3)°
Data collection top
Bruker Kappa APEXII area-detector
diffractometer
2311 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2001)
2023 reflections with I > 2σ(I)
Tmin = 0.985, Tmax = 0.989Rint = 0.020
11727 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0390 restraints
wR(F2) = 0.104H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.22 e Å3
2311 reflectionsΔρmin = 0.16 e Å3
153 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.

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
N10.1812 (2)0.23573 (12)0.32312 (10)0.0440 (3)
C20.17511 (19)0.25258 (11)0.45994 (11)0.0320 (3)
N30.32230 (18)0.36886 (10)0.46055 (9)0.0348 (3)
C40.4384 (2)0.40747 (12)0.34701 (11)0.0348 (3)
C50.3691 (2)0.31781 (12)0.24982 (11)0.0346 (3)
C60.0713 (2)0.27667 (14)0.52388 (13)0.0438 (3)
H6A0.17070.20530.50790.053*
H6B0.12800.35790.48660.053*
C70.0869 (3)0.28619 (17)0.66709 (14)0.0553 (4)
H7A0.00180.36340.68340.066*
H7B0.24800.29640.70420.066*
C80.0116 (3)0.16453 (18)0.72887 (14)0.0630 (5)
H8A0.08190.08820.71930.076*
H8B0.00650.17480.81900.076*
C90.2598 (3)0.14319 (15)0.66826 (14)0.0544 (4)
H9A0.31840.06290.70610.065*
H9B0.35570.21600.68450.065*
C100.2759 (2)0.13315 (12)0.52573 (13)0.0416 (3)
H10A0.19360.05470.51010.050*
H10B0.43750.12390.48920.050*
C110.5811 (2)0.23629 (14)0.20042 (13)0.0445 (3)
H11A0.70960.29530.16720.053*
H11B0.62650.18140.27040.053*
C120.5332 (3)0.14931 (15)0.09662 (13)0.0529 (4)
H12A0.67330.10220.06570.064*
H12B0.41450.08480.13150.064*
C130.4534 (3)0.23098 (16)0.01285 (13)0.0577 (4)
H13A0.57810.28930.05320.069*
H13B0.41590.17310.07560.069*
C140.2427 (3)0.31170 (16)0.03279 (13)0.0572 (4)
H14A0.11250.25310.06360.069*
H14B0.20200.36750.03790.069*
C150.2867 (3)0.39759 (14)0.13896 (12)0.0467 (3)
H15A0.40290.46380.10480.056*
H15B0.14460.44290.16970.056*
O10.58158 (18)0.49753 (9)0.32312 (8)0.0496 (3)
H30.345 (3)0.4032 (16)0.5305 (15)0.053 (4)*
H10.043 (4)0.265 (2)0.301 (2)0.097 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0481 (7)0.0532 (7)0.0324 (6)0.0184 (5)0.0079 (5)0.0091 (5)
C20.0332 (6)0.0333 (6)0.0310 (6)0.0062 (5)0.0078 (5)0.0063 (5)
N30.0434 (6)0.0335 (5)0.0290 (5)0.0089 (4)0.0078 (4)0.0070 (4)
C40.0404 (6)0.0332 (6)0.0323 (6)0.0054 (5)0.0089 (5)0.0047 (5)
C50.0399 (6)0.0357 (6)0.0294 (6)0.0071 (5)0.0076 (5)0.0054 (5)
C60.0334 (7)0.0506 (8)0.0486 (8)0.0011 (6)0.0088 (5)0.0054 (6)
C70.0424 (8)0.0719 (10)0.0494 (8)0.0067 (7)0.0067 (6)0.0177 (7)
C80.0770 (11)0.0735 (11)0.0361 (8)0.0247 (9)0.0025 (7)0.0021 (7)
C90.0700 (10)0.0470 (8)0.0491 (8)0.0036 (7)0.0236 (7)0.0091 (6)
C100.0433 (7)0.0316 (6)0.0512 (8)0.0003 (5)0.0098 (6)0.0051 (5)
C110.0459 (7)0.0468 (7)0.0424 (7)0.0003 (6)0.0091 (6)0.0098 (6)
C120.0659 (9)0.0470 (8)0.0465 (8)0.0030 (7)0.0041 (7)0.0166 (6)
C130.0811 (11)0.0589 (9)0.0338 (7)0.0059 (8)0.0051 (7)0.0151 (6)
C140.0735 (10)0.0669 (10)0.0363 (7)0.0019 (8)0.0219 (7)0.0100 (7)
C150.0609 (9)0.0459 (8)0.0359 (7)0.0046 (6)0.0135 (6)0.0063 (6)
O10.0645 (6)0.0472 (5)0.0371 (5)0.0263 (5)0.0055 (4)0.0052 (4)
Geometric parameters (Å, º) top
N1—C51.4724 (16)C8—H8B0.97
N1—C21.4759 (15)C9—C101.5192 (19)
N1—H10.91 (2)C9—H9A0.97
C2—N31.4652 (14)C9—H9B0.97
C2—C61.5203 (17)C10—H10A0.97
C2—C101.5213 (17)C10—H10B0.97
N3—C41.3300 (16)C11—C121.5213 (18)
N3—H30.872 (17)C11—H11A0.97
C4—O11.2296 (15)C11—H11B0.97
C4—C51.5255 (15)C12—C131.516 (2)
C5—C151.5243 (18)C12—H12A0.97
C5—C111.5315 (18)C12—H12B0.97
C6—C71.5260 (19)C13—C141.511 (2)
C6—H6A0.97C13—H13A0.97
C6—H6B0.97C13—H13B0.97
C7—C81.514 (2)C14—C151.5281 (18)
C7—H7A0.97C14—H14A0.97
C7—H7B0.97C14—H14B0.97
C8—C91.514 (2)C15—H15A0.97
C8—H8A0.97C15—H15B0.97
C5—N1—C2109.28 (9)C10—C9—H9A109.4
C5—N1—H1108.7 (14)C8—C9—H9B109.4
C2—N1—H1107.6 (14)C10—C9—H9B109.4
N3—C2—N1103.04 (9)H9A—C9—H9B108.0
N3—C2—C6111.13 (10)C9—C10—C2112.71 (11)
N1—C2—C6110.88 (10)C9—C10—H10A109.0
N3—C2—C10110.55 (9)C2—C10—H10A109.0
N1—C2—C10111.11 (10)C9—C10—H10B109.0
C6—C2—C10109.97 (10)C2—C10—H10B109.0
C4—N3—C2113.89 (9)H10A—C10—H10B107.8
C4—N3—H3123.1 (10)C12—C11—C5112.13 (11)
C2—N3—H3122.6 (10)C12—C11—H11A109.2
O1—C4—N3126.68 (11)C5—C11—H11A109.2
O1—C4—C5125.05 (11)C12—C11—H11B109.2
N3—C4—C5108.25 (10)C5—C11—H11B109.2
N1—C5—C15111.71 (11)H11A—C11—H11B107.9
N1—C5—C4103.74 (9)C13—C12—C11110.91 (12)
C15—C5—C4111.26 (10)C13—C12—H12A109.5
N1—C5—C11112.27 (11)C11—C12—H12A109.5
C15—C5—C11109.53 (10)C13—C12—H12B109.5
C4—C5—C11108.18 (10)C11—C12—H12B109.5
C2—C6—C7112.42 (11)H12A—C12—H12B108.0
C2—C6—H6A109.1C14—C13—C12111.04 (12)
C7—C6—H6A109.1C14—C13—H13A109.4
C2—C6—H6B109.1C12—C13—H13A109.4
C7—C6—H6B109.1C14—C13—H13B109.4
H6A—C6—H6B107.9C12—C13—H13B109.4
C8—C7—C6111.17 (12)H13A—C13—H13B108.0
C8—C7—H7A109.4C13—C14—C15111.62 (12)
C6—C7—H7A109.4C13—C14—H14A109.3
C8—C7—H7B109.4C15—C14—H14A109.3
C6—C7—H7B109.4C13—C14—H14B109.3
H7A—C7—H7B108.0C15—C14—H14B109.3
C7—C8—C9110.33 (12)H14A—C14—H14B108.0
C7—C8—H8A109.6C5—C15—C14112.45 (11)
C9—C8—H8A109.6C5—C15—H15A109.1
C7—C8—H8B109.6C14—C15—H15A109.1
C9—C8—H8B109.6C5—C15—H15B109.1
H8A—C8—H8B108.1C14—C15—H15B109.1
C8—C9—C10111.04 (12)H15A—C15—H15B107.8
C8—C9—H9A109.4
C5—N1—C2—N313.53 (13)C10—C2—C6—C753.21 (14)
C5—N1—C2—C6132.50 (11)C2—C6—C7—C855.77 (16)
C5—N1—C2—C10104.88 (12)C6—C7—C8—C956.55 (17)
N1—C2—N3—C49.88 (14)C7—C8—C9—C1056.59 (17)
C6—C2—N3—C4128.68 (11)C8—C9—C10—C255.99 (16)
C10—C2—N3—C4108.91 (12)N3—C2—C10—C969.59 (14)
C2—N3—C4—O1176.02 (12)N1—C2—C10—C9176.64 (11)
C2—N3—C4—C52.38 (14)C6—C2—C10—C953.49 (14)
C2—N1—C5—C15132.29 (11)N1—C5—C11—C1269.59 (14)
C2—N1—C5—C412.35 (13)C15—C5—C11—C1255.11 (15)
C2—N1—C5—C11104.22 (12)C4—C5—C11—C12176.55 (11)
O1—C4—C5—N1175.37 (12)C5—C11—C12—C1356.86 (16)
N3—C4—C5—N16.20 (13)C11—C12—C13—C1456.04 (17)
O1—C4—C5—C1555.12 (17)C12—C13—C14—C1554.99 (18)
N3—C4—C5—C15126.44 (12)N1—C5—C15—C1471.20 (15)
O1—C4—C5—C1165.24 (16)C4—C5—C15—C14173.39 (12)
N3—C4—C5—C11113.19 (12)C11—C5—C15—C1453.83 (15)
N3—C2—C6—C769.54 (14)C13—C14—C15—C554.77 (17)
N1—C2—C6—C7176.48 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O1i0.87 (2)2.02 (2)2.8821 (14)172 (1)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC13H22N2O
Mr222.33
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)5.8270 (8), 10.1703 (5), 10.6651 (4)
α, β, γ (°)86.103 (2), 81.331 (3), 89.720 (3)
V3)623.36 (9)
Z2
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.20 × 0.15 × 0.15
Data collection
DiffractometerBruker Kappa APEXII area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2001)
Tmin, Tmax0.985, 0.989
No. of measured, independent and
observed [I > 2σ(I)] reflections
11727, 2311, 2023
Rint0.020
(sin θ/λ)max1)0.605
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.039, 0.104, 1.04
No. of reflections2311
No. of parameters153
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.22, 0.16

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), PLATON (Spek, 2009), SHELXL97 (Sheldrick, 2008) and PARST (Nardelli, 1995).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O1i0.87 (2)2.02 (2)2.8821 (14)172 (1)
Symmetry code: (i) x+1, y+1, z+1.
 

Acknowledgements

TK thanks the CSIR, India, for financial support in the form of a Senior Research Fellowship. SP thanks the UGC, India, for financial support.

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brummer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CrossRef
First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science
First citationBruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science
First citationNardelli, M. (1995). J. Appl. Cryst. 28, 659.  CrossRef IUCr Journals
First citationSheldrick, G. M. (2001). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals
First citationTsao, T. C., Williams, D. E., Worley, C. G. & Worley, S. D. (1991). Biotechnol. Prog. 7, 60–66.  CrossRef CAS Web of Science
First citationWang, W., Liang, T. C., Zheng, M. & Gao, X. (1995). Tetrahedron Lett. 36, 1181–1184.  CrossRef CAS Web of Science

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 66| Part 5| May 2010| Page o1072
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds