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

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Methyl 3,6-an­hydro-4-azido-5,7-O-(S)-benzyl­­idene-2,4-di­de­oxy-D-talo-heptonate

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aDepartment of Organic Chemistry, Chemistry Research Laboratory, Oxford OX1 3TA, England, bMolecular Nature Ltd, Institute of Grassland and Environmental Research, Aberystwyth SY23 3EB, Dyfed, Wales, and cDepartment of Chemical Crystallography, Chemistry Research Laboratory, Oxford OX1 3TA, England
*Correspondence e-mail: christopher.newton@new.ox.ac.uk

(Received 19 March 2004; accepted 5 April 2004; online 24 April 2004)

The title compound, C15H17N3O5, was formed by carrying out a Wittig reaction, under basic conditions, on 2-azido-3,5–O-benzyl­idene-2-deoxy-D-lyxose.

Comment

Sugar amino acids (SAA) (Schweizer, 2002[Schweizer, F. (2002). Angew. Chem. Int. Ed. 41, 231-253.]) have been utilized in peptidomimetics (Gruner et al., 2002[Gruner, S. A. W., Locardi, E., Lohof, E. & Kessler, H. (2002). Chem. Rev. 102, 491-514.]), as carbopeptoid foldamers (Gellman, 1998[Gellman, S. H. (1998). Acc. Chem. Res. 31, 173-180.]) and, to a lesser extent, as molecular scaffolds (Sofia, 1998[Sofia, M. J. (1998). Med. Chem. Res. 8, 362-378.]). Although the generation of well defined libraries from SAA is rare (Chakraborty et al., 2003[Chakraborty, T. K., Jayaprakash, S. & Ghosh, S. (2003). Comb. Chem. High Throughput Screening, 5, 373-387.]; Edwards et al., 2004[Edwards, A. A., Ichihara, O., Murfin, S., Wilkes, R., Watkin, D. J. & Fleet, G. W. J. (2004). J. Combinatorial Chem. 6, 230-238.]), SAA peptidomimetics have been employed as chiral scaffolds in the parallel production of ligands for the melanocortin and somastatin GPCR receptors (Le et al., 2003[Le, G. T., Abbenante, G., Becker, B., Gratwohl, M., Halliday, J., Tometzki, G., Zuegg, J. & Meutermans, W. (2003). Drug Discovery Today, 8, 701-709.]). The recognition of templated SAA in forming different but predictable secondary structure is likely to lead to further exploitation of this structural motif (Smith et al., 2003[Smith, M. D., Claridge, T. D. W., Sansom, M. P. & Fleet, G. W. J. (1996). Org. Biomol. Chem. 1, 3647-3655.]). A wide range of tetra­hydro­furan (THF) amino acid scaffolds are readily available (Watterson et al., 1996[Watterson, M. P., Edwards, A. A., Leach, J. A., Smith, M. D., Ichihara, O. & Fleet, G. W. J. (2003). Tetrahedron Lett. 44, 5853-5857.]) and a series of γ-THF amino acids have recently been reported (Sanjayan et al., 2003[Sanjayan, G., Stewart, A., Hachisu, S., Gonzalez, R., Watterson, M. P. & Fleet, G. W. J. (2003). Tetrahedron Lett. 44, 5847-5852.]). The title compound, (3[link]), is an example of a γ-THF amino acid with a different structural motif. A novel THF scaffold (3[link]) with an azide directly attached to the THF was prepared in good yield by the three-step one-pot procedure outlined below. Reduction of azido lactone (1[link]) with 1.5 equivalents of diiso­butyl­aluminium hydride, DIBAL-H, provided a lactol that was immediately subjected to Wittig olefination to afford the enoate (2[link]). Upon prolonged stirring, (2[link]) underwent a conjugate addition of the unprotected OH group to the enoate (2[link]) to give the highly functionalized scaffold (3[link]) in good yield; optimization of the conditions for the overall sequence are currently being investigated. Two structural ambiguities arose in the formation of (3[link]): one based on the easy epimerization of azides in azido­lactones (Krulle et al., 1996[Krulle, T. M., Davis, B. G., Ardron, H., Long, D. D., Hindle, N. A., Smith, C., Brown, D., Lane, A. L., Watkin, D. J., Marquess, D. G. & Fleet, G. W. J. (1996). J. Chem. Soc. Chem. Commun. pp. 1271-1272.]) and the other on the new stereogenic centre generated by the intramolecular Michael addition. These uncertainties were firmly resolved by single-crystal X-ray crystallography of the title compound (3[link]).[link]

[Scheme 1]
[Figure 1]
Figure 1
The molecular structure of (3), with 50% probability displacement ellipsoids.

Experimental

The title material was obtained by solvent evaporation (EtOAc–cyclo­hexane), appearing as orange–yellow block-shaped crystals. These were recrystallized from methanol to give colourless plate-like crystals.

Crystal data
  • C15H17N3O5

  • Mr = 319.32

  • Monoclinic, P21

  • a = 8.2135 (3) Å

  • b = 9.2262 (3) Å

  • c = 10.9944 (3) Å

  • β = 108.0414 (15)°

  • V = 792.19 (4) Å3

  • Z = 2

  • Dx = 1.339 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 1851 reflections

  • θ = 5–27°

  • μ = 0.10 mm−1

  • T = 293 K

  • Plate, colourless

  • 0.40 × 0.40 × 0.10 mm

Data collection
  • Nonius KappaCCD diffractometer

  • ω scans

  • Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307-326. New York: Academic Press.]) Tmin = 0.96, Tmax = 0.99

  • 3420 measured reflections

  • 1906 independent reflections

  • 1464 reflections with I > 2.00 σ(I)

  • Rint = 0.011

  • θmax = 27.5°

  • h = −10 → 10

  • k = −11 → 11

  • l = −14 → 14

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.035

  • wR(F2) = 0.092

  • S = 0.89

  • 1906 reflections

  • 209 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(F*) + (0.0434p)2 + 0.113p] where p = 0.333max(Fo2,0) + 0.667Fc2

  • (Δ/σ)max = 0.002

  • Δρmax = 0.17 e Å−3

  • Δρmin = −0.15 e Å−3

  • Extinction correction: Larson (1970[Larson, A. C. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall and C. P. Huber, pp. 291-294. Copenhagen: Munksgaard.])

  • Extinction coefficient: 4.3 (6) × 102

Table 1
Selected geometric parameters (Å, °)

C1—O9 1.437 (2)
C1—C5 1.517 (3)
C1—C2 1.513 (4)
C2—N21 1.464 (3)
C2—C3 1.537 (3)
C3—C16 1.523 (3)
C3—O4 1.419 (3)
O4—C5 1.444 (3)
C5—C6 1.491 (4)
C6—O7 1.432 (3)
O7—C8 1.408 (3)
C8—C10 1.499 (3)
C8—O9 1.421 (3)
C10—C15 1.368 (4)
C10—C11 1.396 (4)
C11—C12 1.375 (4)
C12—C13 1.361 (6)
C13—C14 1.365 (6)
C14—C15 1.392 (4)
C16—C17 1.502 (4)
C17—O20 1.186 (3)
C17—O18 1.320 (3)
O18—C19 1.453 (3)
N21—N22 1.232 (4)
N22—N23 1.133 (4)
O9—C1—C5 111.79 (19)
O9—C1—C2 105.98 (19)
C5—C1—C2 101.85 (19)
N21—C2—C3 115.4 (2)
N21—C2—C1 116.74 (19)
C3—C2—C1 102.4 (2)
C16—C3—O4 110.4 (2)
C16—C3—C2 112.3 (2)
O4—C3—C2 105.1 (2)
C5—O4—C3 110.88 (18)
C6—C5—O4 110.1 (2)
C6—C5—C1 113.1 (2)
O4—C5—C1 105.3 (2)
O7—C6—C5 112.12 (19)
C8—O7—C6 110.38 (18)
C10—C8—O9 106.41 (17)
C10—C8—O7 109.96 (19)
O9—C8—O7 109.96 (18)
C8—O9—C1 113.72 (16)
C15—C10—C11 119.8 (2)
C15—C10—C8 121.2 (2)
C11—C10—C8 119.0 (2)
C12—C11—C10 119.7 (3)
C13—C12—C11 120.2 (3)
C14—C13—C12 120.7 (3)
C15—C14—C13 120.1 (4)
C10—C15—C14 119.6 (3)
C17—C16—C3 114.7 (2)
O20—C17—O18 123.5 (3)
O20—C17—C16 124.4 (3)
O18—C17—C16 112.1 (2)
C19—O18—C17 116.2 (2)
N22—N21—C2 115.7 (2)
N23—N22—N21 171.7 (3)

H atoms were placed geometrically after each cycle, at a distance of 1.0 Å; Uiso values were set to 1.2 times the Ueq value of the parent atom. The absolute configuration was assumed to be the same as that of the sugar and the Friedel pairs were merged in the final refinement.

Data collection: COLLECT (Nonius, 1997–2001[Nonius (1997-2001). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.]); molecular graphics: CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.]); software used to prepare material for publication: CRYSTALS.

Supporting information


Computing details top

Data collection: COLLECT (Nonius, 1997); cell refinement: DENZO/SCALEPACK; data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1996); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al. 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al. 2003).

Methyl 3,6-anhydro-4-azido-5,7-O-(S)-benzylidene-2,4-dideoxy-D-talo-heptonate top
Crystal data top
C15H17N3O5F(000) = 336
Mr = 319.32Dx = 1.339 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
a = 8.2135 (3) ÅCell parameters from 1851 reflections
b = 9.2262 (3) Åθ = 5–27°
c = 10.9944 (3) ŵ = 0.10 mm1
β = 108.0414 (15)°T = 293 K
V = 792.19 (4) Å3Plate, colourless
Z = 20.40 × 0.40 × 0.10 mm
Data collection top
Nonius KappaCCD
diffractometer
1464 reflections with I > 2.00u(I)
Graphite monochromatorRint = 0.01
ω scansθmax = 27.5°, θmin = 5.1°
Absorption correction: multi-scan
(DENZO/SCALEPACK; Otwinowski & Minor, 1996)
h = 1010
Tmin = 0.96, Tmax = 0.99k = 1111
3420 measured reflectionsl = 1414
1906 independent reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.035 w = 1/[σ2(F*) + (0.0434p)2 + 0.113p]
where p = 0.333max(Fo2,0) + 0.667Fc2
wR(F2) = 0.092(Δ/σ)max = 0.002
S = 0.89Δρmax = 0.17 e Å3
1906 reflectionsΔρmin = 0.15 e Å3
209 parametersExtinction correction: Larson 1970 Crystallographic Computing eq 22
1 restraintExtinction coefficient: 430 (60)
Primary atom site location: structure-invariant direct methods
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.6257 (3)0.3880 (2)0.6894 (2)0.0578
C20.7296 (3)0.3406 (3)0.8225 (2)0.0602
C30.6887 (3)0.1780 (3)0.8208 (2)0.0544
O40.5199 (2)0.1644 (2)0.73553 (18)0.0720
C50.4647 (3)0.2976 (3)0.6661 (3)0.0652
C60.3786 (3)0.2660 (3)0.5281 (3)0.0711
O70.4980 (2)0.22373 (19)0.46346 (16)0.0629
C80.6232 (3)0.3318 (3)0.4764 (2)0.0539
O90.72305 (18)0.34582 (17)0.60683 (13)0.0523
C100.7445 (3)0.2885 (3)0.4051 (2)0.0552
C110.8300 (3)0.1560 (3)0.4336 (3)0.0705
C120.9423 (4)0.1152 (4)0.3696 (3)0.0915
C130.9725 (4)0.2047 (5)0.2805 (3)0.0993
C140.8901 (5)0.3346 (5)0.2521 (3)0.0952
C150.7747 (4)0.3775 (3)0.3149 (2)0.0712
C160.6979 (4)0.1208 (3)0.9527 (2)0.0706
C170.6358 (4)0.0321 (3)0.9541 (2)0.0622
O180.7011 (3)0.1205 (2)0.8869 (2)0.0799
C190.6553 (5)0.2725 (3)0.8879 (3)0.0857
O200.5424 (4)0.0707 (3)1.0110 (3)0.1000
N210.9120 (3)0.3774 (3)0.8639 (2)0.0763
N221.0011 (3)0.3082 (3)0.8126 (2)0.0764
N231.0993 (3)0.2529 (4)0.7754 (3)0.1079
H110.59910.49370.67620.0727*
H210.69690.39530.89000.0752*
H310.77430.12000.79340.0668*
H510.37770.35160.69510.0802*
H610.31680.35510.48600.0829*
H620.29430.18580.52100.0829*
H810.56310.42450.44240.0635*
H1110.80950.09100.50040.0817*
H1211.00240.01960.38860.1060*
H1311.05580.17490.23530.1192*
H1410.91280.39930.18600.1164*
H1510.71430.47280.29420.0857*
H1610.82020.12511.00830.0886*
H1620.62690.18520.98920.0886*
H1910.71110.32930.83440.1061*
H1920.69480.30970.97780.1061*
H1930.52800.28310.85240.1061*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0694 (14)0.0348 (11)0.0799 (14)0.0026 (11)0.0387 (12)0.0072 (11)
C20.0787 (16)0.0408 (12)0.0713 (13)0.0136 (12)0.0380 (12)0.0090 (11)
C30.0600 (13)0.0399 (11)0.0697 (13)0.0068 (11)0.0294 (11)0.0063 (10)
O40.0648 (10)0.0493 (9)0.1030 (13)0.0126 (9)0.0276 (9)0.0109 (10)
C50.0563 (13)0.0499 (13)0.0971 (17)0.0039 (11)0.0349 (13)0.0052 (13)
C60.0451 (12)0.0570 (15)0.108 (2)0.0039 (12)0.0188 (13)0.0069 (15)
O70.0491 (8)0.0478 (9)0.0862 (11)0.0051 (8)0.0125 (8)0.0093 (8)
C80.0542 (12)0.0384 (11)0.0683 (12)0.0007 (11)0.0178 (10)0.0024 (10)
O90.0536 (8)0.0445 (9)0.0629 (8)0.0091 (7)0.0238 (7)0.0084 (7)
C100.0547 (12)0.0485 (13)0.0588 (11)0.0002 (11)0.0124 (10)0.0119 (11)
C110.0645 (15)0.0583 (15)0.0834 (16)0.0093 (13)0.0151 (13)0.0107 (14)
C120.0766 (18)0.090 (2)0.101 (2)0.0251 (18)0.0171 (17)0.0306 (19)
C130.076 (2)0.134 (4)0.091 (2)0.012 (2)0.0308 (17)0.039 (2)
C140.094 (2)0.126 (3)0.0740 (16)0.000 (2)0.0378 (16)0.013 (2)
C150.0795 (17)0.0705 (18)0.0670 (13)0.0040 (15)0.0277 (13)0.0079 (14)
C160.107 (2)0.0459 (14)0.0704 (14)0.0090 (14)0.0446 (15)0.0049 (12)
C170.0870 (17)0.0486 (13)0.0581 (13)0.0026 (13)0.0327 (13)0.0009 (11)
O180.1059 (15)0.0488 (11)0.1039 (14)0.0088 (10)0.0601 (12)0.0129 (10)
C190.113 (3)0.0477 (15)0.106 (2)0.0046 (17)0.047 (2)0.0117 (14)
O200.162 (2)0.0595 (12)0.1151 (15)0.0126 (14)0.0962 (17)0.0001 (11)
N210.0880 (16)0.0674 (15)0.0744 (13)0.0312 (13)0.0263 (12)0.0161 (12)
N220.0641 (14)0.0817 (18)0.0783 (14)0.0264 (14)0.0147 (11)0.0003 (14)
N230.0623 (15)0.133 (3)0.130 (2)0.0115 (19)0.0331 (17)0.001 (2)
Geometric parameters (Å, º) top
C1—H111.000C10—C111.396 (4)
C1—O91.437 (2)C11—H1111.002
C1—C51.517 (3)C11—C121.375 (4)
C1—C21.513 (4)C12—H1211.001
C2—H211.000C12—C131.361 (6)
C2—N211.464 (3)C13—H1311.001
C2—C31.537 (3)C13—C141.365 (6)
C3—H311.001C14—H1411.001
C3—C161.523 (3)C14—C151.392 (4)
C3—O41.419 (3)C15—H1511.001
O4—C51.444 (3)C16—H1620.999
C5—H511.001C16—H1611.002
C5—C61.491 (4)C16—C171.502 (4)
C6—H621.000C17—O201.186 (3)
C6—H611.001C17—O181.320 (3)
C6—O71.432 (3)O18—C191.453 (3)
O7—C81.408 (3)C19—H1931.001
C8—H811.001C19—H1921.001
C8—C101.499 (3)C19—H1910.998
C8—O91.421 (3)N21—N221.232 (4)
C10—C151.368 (4)N22—N231.133 (4)
H11—C1—O9108.170C8—O9—C1113.72 (16)
H11—C1—C5111.834C15—C10—C11119.8 (2)
O9—C1—C5111.79 (19)C15—C10—C8121.2 (2)
H11—C1—C2117.051C11—C10—C8119.0 (2)
O9—C1—C2105.98 (19)H111—C11—C12120.184
C5—C1—C2101.85 (19)H111—C11—C10120.109
H21—C2—N2197.832C12—C11—C10119.7 (3)
H21—C2—C3113.240H121—C12—C13119.784
N21—C2—C3115.4 (2)H121—C12—C11120.033
H21—C2—C1111.780C13—C12—C11120.2 (3)
N21—C2—C1116.74 (19)H131—C13—C14119.623
C3—C2—C1102.4 (2)H131—C13—C12119.722
H31—C3—C16105.628C14—C13—C12120.7 (3)
H31—C3—O4112.780H141—C14—C15119.950
C16—C3—O4110.4 (2)H141—C14—C13119.942
H31—C3—C2110.792C15—C14—C13120.1 (4)
C16—C3—C2112.3 (2)H151—C15—C10120.260
O4—C3—C2105.1 (2)H151—C15—C14120.169
C5—O4—C3110.88 (18)C10—C15—C14119.6 (3)
H51—C5—C6105.154H162—C16—H161109.357
H51—C5—O4113.166H162—C16—C17108.240
C6—C5—O4110.1 (2)H161—C16—C17108.084
H51—C5—C1110.120H162—C16—C3108.243
C6—C5—C1113.1 (2)H161—C16—C3108.149
O4—C5—C1105.3 (2)C17—C16—C3114.7 (2)
H62—C6—H61109.403O20—C17—O18123.5 (3)
H62—C6—O7108.873O20—C17—C16124.4 (3)
H61—C6—O7108.792O18—C17—C16112.1 (2)
H62—C6—C5108.829C19—O18—C17116.2 (2)
H61—C6—C5108.793H193—C19—H192109.351
O7—C6—C5112.12 (19)H193—C19—H191109.535
C8—O7—C6110.38 (18)H192—C19—H191109.543
H81—C8—C10111.363H193—C19—O18109.420
H81—C8—O9111.259H192—C19—O18109.412
C10—C8—O9106.41 (17)H191—C19—O18109.566
H81—C8—O7107.889N22—N21—C2115.7 (2)
C10—C8—O7109.96 (19)N23—N22—N21171.7 (3)
O9—C8—O7109.96 (18)
 

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