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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 3| March 2015| Pages o146-o147

Crystal structure of (3S)-3-acet­­oxy-17-(pyridin-3-yl)androsta-5,16-diene

CROSSMARK_Color_square_no_text.svg

aHangzhou Jiuyuan Gene Engineering Co. Ltd, Hangzhou 310018, Zhejiang, People's Republic of China, and bDepartment of Chemistry, Xiamen University, Xiamen 361005, People's Republic of China
*Correspondence e-mail: rbhuang@xmu.edu.cn

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 26 January 2015; accepted 30 January 2015; online 4 February 2015)

In the title compound, C26H33NO2 [systematic name: (3S,8R,9S,10R,13S,14S)-10,13-dimethyl-17-(pyridin-3-yl)-2,3,4,7,8,9,10,11,12,13,14,15-dodeca­hydro-1H-cyclo­penta­[a]phenanthren-3-yl acetate], the steroid A, B, C and D rings adopt chair, half-chair, chair and envelope conformations, respectively. The flap atom of the envelope is the methine C atom fused with the C ring. In the crystal, adjacent mol­ecules, generated by a 21 screw axis, are linked by weak C—H⋯O hydrogen bonds, forming a C(16) helical chain running along the c-axis direction.

1. Related literature

For inhibition of the androgen signal axis in prostate cancer cells, see: Attard et al. (2009[Attard, G., et al. (2009). J. Clin. Oncol. 27, 3742-3748.]). For use of the title compound as an inhibitor of human cytochrome P45017a and the absolute structure of the precursor mol­ecule, see: Potter et al. (1995[Potter, G. A., Barrie, S. E., Jarman, M. & Rowlands, M. G. (1995). J. Med. Chem. 38, 2463-2471.]).

[Scheme 1]

2. Experimental

2.1. Crystal data

  • C26H33NO2

  • Mr = 391.53

  • Orthorhombic, P 21 21 21

  • a = 7.5180 (5) Å

  • b = 9.7274 (5) Å

  • c = 30.2035 (15) Å

  • V = 2208.8 (2) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.07 mm−1

  • T = 283 K

  • 0.40 × 0.40 × 0.35 mm

2.2. Data collection

  • Bruker SMART APEX 2000 diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.971, Tmax = 0.975

  • 12750 measured reflections

  • 4320 independent reflections

  • 3261 reflections with I > 2σ(I)

  • Rint = 0.033

2.3. Refinement

  • R[F2 > 2σ(F2)] = 0.056

  • wR(F2) = 0.128

  • S = 1.06

  • 4320 reflections

  • 262 parameters

  • H-atom parameters constrained

  • Δρmax = 0.18 e Å−3

  • Δρmin = −0.20 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C21—H21A⋯O2i 0.93 2.70 3.520 (6) 147
Symmetry code: (i) [-x+{\script{1\over 2}}, -y+2, z+{\script{1\over 2}}].

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: SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]); molecular graphics: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]) and Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]); software used to prepare material for publication: SHELXL2014 and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

Castration-resistant prostate cancer (CRPC) is thought to be hormone driven. Inhibition of the androgen signal axis remains an important treatment strategy for CRPC (Attard et al., 2009). The title compound, 3S-acetoxy-17-(pyridin-3-yl)androsta-5,16-diene, also referred to as abiraterone acetate, (Scheme I), is a pro-drug for 17-(pyridin-3-yl)androsta-5,16-dien-3P-ol, or abiraterone, a potent inhibitor of human cytochrome P45017a (steroidal 17α-hydroxylase-C~17,20~-lyase). Abiraterone acetate was first synthesized and charaterized by Potter et al. (1995), but structural data were not obtained. In this work, we obtained a single-crystal of the title compound (I) and we present its structure here. The space group was non-centrosymmetric confirming the chiral structure. However with no heavy atom, the absolute structure cannot be determined reliably but the absolute structure (Fig.1) has been assigned based on that of the precursor compound dehydro-epiandrosterone (Potter et al., 1995).

In the molecule, there are six chiral carbon atoms. The molecule contains a fused four-ring system. The two saturated six-membered rings adopt chair conformations while the five-membered ring is in an envelope conformation on C14. The six-membered ring with the carbon-carbon double bond approximates to a half chair form. A 21 screw chain running along the c axis, Fig. 2 is formed through weak C21–H21A···O2 hydrogen bonds, Table 1.

Related literature top

For inhibition of the androgen signal axis in prostate cancer cells, see: Attard et al. (2009). For use of the title compound as an inhibitor of human cytochrome P45017a and the absolute structure of the precursor molecule, see: Potter et al. (1995).

Experimental top

Abiraterone acetate was synthesized from dehydro-epiandrosterone acetate via enol esterification and Suzuki coupling with an overall yield of 72% according to a literature method (Potter, 1995). Colorless blocks were obtained by evaporation from an ethyl acetate solution.

Refinement top

All H atoms bound to carbon were refined using a riding model with d(C—H) = 0.93 Å, for aromatic, 0.98 Å for C—H and 0.97 Å for CH2 with Uiso=1.2Ueq (C). d(C—H) = 0.96 Å with Uiso = 1.5Ueq (C) for CH3 H atoms. The absolute structure could not be determined reliably and Friedel pairs were merged prior to the final refinement. A Flack parameter is not reported.

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: SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with displacement ellipsoids are drawn at 50% probability level.
[Figure 2] Fig. 2. Crystal packing for (I) viewed along the a axis.
(3S,8R,9S,10R,13S,14S)-10,13-Dimethyl-17-(pyridin-3-yl)-2,3,4,7,8,9,10,11,12,13,14,15-dodecahydro-1H-cyclopenta[a]phenanthren-3-yl acetate top
Crystal data top
C26H33NO2Dx = 1.177 Mg m3
Mr = 391.53Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121Cell parameters from 1526 reflections
a = 7.5180 (5) Åθ = 3.3–26.3°
b = 9.7274 (5) ŵ = 0.07 mm1
c = 30.2035 (15) ÅT = 283 K
V = 2208.8 (2) Å3Block, colorless
Z = 40.40 × 0.40 × 0.35 mm
F(000) = 848
Data collection top
Bruker SMART APEX 2000
diffractometer
4320 independent reflections
Radiation source: Enhance (Mo) X-ray Source3261 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.033
ϕ and ω scansθmax = 26.0°, θmin = 3.4°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 99
Tmin = 0.971, Tmax = 0.975k = 1111
12750 measured reflectionsl = 3737
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.056H-atom parameters constrained
wR(F2) = 0.128 w = 1/[σ2(Fo2) + (0.056P)2 + 0.2757P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max < 0.001
4320 reflectionsΔρmax = 0.18 e Å3
262 parametersΔρmin = 0.20 e Å3
Crystal data top
C26H33NO2V = 2208.8 (2) Å3
Mr = 391.53Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.5180 (5) ŵ = 0.07 mm1
b = 9.7274 (5) ÅT = 283 K
c = 30.2035 (15) Å0.40 × 0.40 × 0.35 mm
Data collection top
Bruker SMART APEX 2000
diffractometer
4320 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
3261 reflections with I > 2σ(I)
Tmin = 0.971, Tmax = 0.975Rint = 0.033
12750 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0560 restraints
wR(F2) = 0.128H-atom parameters constrained
S = 1.06Δρmax = 0.18 e Å3
4320 reflectionsΔρmin = 0.20 e Å3
262 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.4502 (4)0.5976 (3)0.55529 (9)0.0797 (8)
O20.4415 (9)0.8126 (5)0.53343 (14)0.160 (2)
N10.1444 (5)0.7589 (5)0.93757 (11)0.0853 (11)
C10.2241 (5)0.6778 (4)0.66365 (10)0.0538 (9)
H1A0.09870.68230.67100.065*
H1B0.27580.76690.67010.065*
C20.2422 (5)0.6501 (4)0.61423 (11)0.0663 (10)
H2A0.18100.56530.60680.080*
H2B0.18710.72420.59770.080*
C30.4354 (6)0.6385 (4)0.60138 (11)0.0652 (10)
H3A0.49480.72700.60590.078*
C40.5274 (5)0.5287 (4)0.62823 (11)0.0611 (10)
H4A0.47960.43950.62020.073*
H4B0.65320.52880.62120.073*
C50.5042 (4)0.5503 (3)0.67734 (11)0.0478 (8)
C60.6410 (4)0.5480 (4)0.70470 (12)0.0558 (9)
H6A0.75340.53930.69210.067*
C70.6319 (4)0.5580 (3)0.75376 (11)0.0524 (9)
H7A0.67990.64610.76290.063*
H7B0.70580.48660.76660.063*
C80.4435 (4)0.5437 (3)0.77172 (10)0.0419 (7)
H8A0.41060.44620.77230.050*
C90.3129 (4)0.6220 (3)0.74174 (10)0.0383 (7)
H9A0.35750.71660.74040.046*
C100.3133 (4)0.5694 (3)0.69337 (10)0.0405 (7)
C110.1258 (4)0.6319 (4)0.76150 (10)0.0489 (8)
H11A0.07010.54210.75970.059*
H11B0.05600.69460.74360.059*
C120.1198 (4)0.6809 (3)0.80970 (10)0.0459 (8)
H12A0.15610.77650.81110.055*
H12B0.00120.67450.82070.055*
C130.2424 (4)0.5943 (3)0.83901 (10)0.0419 (7)
C140.4288 (4)0.6028 (3)0.81826 (10)0.0428 (7)
H14A0.45050.70150.81450.051*
C150.5517 (5)0.5602 (4)0.85603 (11)0.0635 (10)
H15A0.56030.46100.85860.076*
H15B0.66990.59890.85260.076*
C160.4549 (5)0.6223 (4)0.89448 (12)0.0638 (10)
H16A0.50770.64100.92170.077*
C170.2853 (4)0.6475 (3)0.88538 (10)0.0496 (8)
C180.1586 (4)0.7184 (3)0.91506 (10)0.0491 (8)
C190.0234 (5)0.6956 (4)0.91332 (12)0.0684 (11)
H19A0.06370.62990.89330.082*
C200.2145 (6)0.8159 (4)0.94512 (11)0.0621 (10)
H20A0.33480.83660.94770.075*
C210.0917 (7)0.8824 (4)0.97126 (12)0.0763 (12)
H21A0.12760.94690.99220.092*
C220.0833 (7)0.8516 (5)0.96583 (13)0.0850 (14)
H22A0.16550.89870.98310.102*
C230.4500 (8)0.6939 (6)0.52476 (15)0.0993 (16)
C240.4541 (9)0.6347 (7)0.47920 (15)0.135 (2)
H24A0.46120.53630.48100.202*
H24B0.34770.66030.46370.202*
H24C0.55590.66940.46360.202*
C250.2137 (5)0.4319 (3)0.68890 (12)0.0564 (9)
H25A0.09330.44300.69890.085*
H25B0.21350.40370.65840.085*
H25C0.27200.36330.70650.085*
C260.1744 (5)0.4447 (4)0.84271 (12)0.0623 (9)
H26A0.14710.41030.81370.093*
H26B0.26460.38840.85600.093*
H26C0.06920.44260.86070.093*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.107 (2)0.0719 (17)0.0607 (15)0.0107 (17)0.0209 (15)0.0040 (14)
O20.283 (6)0.092 (3)0.105 (3)0.029 (4)0.016 (3)0.029 (2)
N10.066 (2)0.124 (3)0.066 (2)0.013 (2)0.0091 (18)0.003 (2)
C10.056 (2)0.051 (2)0.0536 (19)0.0134 (17)0.0029 (16)0.0016 (15)
C20.077 (3)0.067 (2)0.055 (2)0.012 (2)0.0013 (19)0.0028 (19)
C30.085 (3)0.056 (2)0.055 (2)0.011 (2)0.0127 (19)0.0096 (17)
C40.057 (2)0.056 (2)0.071 (2)0.0000 (18)0.0142 (18)0.0080 (18)
C50.0427 (18)0.0363 (17)0.064 (2)0.0015 (14)0.0108 (16)0.0050 (15)
C60.0339 (17)0.053 (2)0.080 (2)0.0041 (17)0.0103 (17)0.0085 (18)
C70.0323 (16)0.0496 (19)0.075 (2)0.0024 (15)0.0032 (16)0.0102 (17)
C80.0309 (15)0.0328 (15)0.0620 (19)0.0017 (14)0.0061 (14)0.0040 (14)
C90.0295 (14)0.0295 (15)0.0558 (18)0.0009 (12)0.0011 (13)0.0013 (13)
C100.0351 (15)0.0308 (15)0.0556 (18)0.0008 (13)0.0011 (13)0.0010 (14)
C110.0363 (17)0.059 (2)0.0512 (18)0.0081 (16)0.0038 (14)0.0012 (16)
C120.0338 (16)0.0510 (18)0.0528 (18)0.0071 (14)0.0013 (14)0.0011 (15)
C130.0357 (15)0.0380 (17)0.0520 (17)0.0016 (14)0.0053 (13)0.0023 (14)
C140.0337 (15)0.0364 (15)0.0583 (18)0.0038 (14)0.0088 (14)0.0007 (14)
C150.0433 (18)0.074 (2)0.073 (2)0.0098 (19)0.0169 (18)0.002 (2)
C160.058 (2)0.078 (3)0.056 (2)0.007 (2)0.0171 (18)0.0013 (18)
C170.0467 (19)0.049 (2)0.0528 (18)0.0002 (16)0.0094 (15)0.0066 (15)
C180.049 (2)0.056 (2)0.0423 (16)0.0006 (17)0.0048 (15)0.0081 (16)
C190.061 (2)0.090 (3)0.054 (2)0.000 (2)0.0017 (18)0.005 (2)
C200.076 (3)0.066 (2)0.0447 (17)0.010 (2)0.0002 (18)0.0053 (18)
C210.102 (4)0.076 (3)0.051 (2)0.003 (3)0.009 (2)0.0027 (19)
C220.098 (4)0.103 (4)0.054 (2)0.025 (3)0.014 (2)0.005 (2)
C230.127 (4)0.099 (4)0.072 (3)0.019 (4)0.022 (3)0.016 (3)
C240.162 (5)0.178 (6)0.064 (3)0.021 (5)0.037 (3)0.008 (3)
C250.057 (2)0.0446 (19)0.068 (2)0.0136 (17)0.0004 (17)0.0082 (17)
C260.062 (2)0.047 (2)0.077 (2)0.0094 (19)0.0028 (19)0.0058 (18)
Geometric parameters (Å, º) top
O1—C231.314 (5)C11—H11B0.9700
O1—C31.452 (4)C12—C131.531 (4)
O2—C231.185 (6)C12—H12A0.9700
N1—C191.321 (5)C12—H12B0.9700
N1—C221.324 (6)C13—C171.527 (4)
C1—C21.523 (4)C13—C141.537 (4)
C1—C101.538 (4)C13—C261.546 (4)
C1—H1A0.9700C14—C151.526 (4)
C1—H1B0.9700C14—H14A0.9800
C2—C31.507 (6)C15—C161.498 (5)
C2—H2A0.9700C15—H15A0.9700
C2—H2B0.9700C15—H15B0.9700
C3—C41.509 (5)C16—C171.328 (5)
C3—H3A0.9800C16—H16A0.9300
C4—C51.508 (4)C17—C181.479 (5)
C4—H4A0.9700C18—C201.378 (5)
C4—H4B0.9700C18—C191.387 (5)
C5—C61.320 (5)C19—H19A0.9300
C5—C101.526 (4)C20—C211.376 (5)
C6—C71.487 (4)C20—H20A0.9300
C6—H6A0.9300C21—C221.359 (7)
C7—C81.524 (4)C21—H21A0.9300
C7—H7A0.9700C22—H22A0.9300
C7—H7B0.9700C23—C241.492 (7)
C8—C141.523 (4)C24—H24A0.9600
C8—C91.537 (4)C24—H24B0.9600
C8—H8A0.9800C24—H24C0.9600
C9—C111.531 (4)C25—H25A0.9600
C9—C101.548 (4)C25—H25B0.9600
C9—H9A0.9800C25—H25C0.9600
C10—C251.538 (4)C26—H26A0.9600
C11—C121.532 (4)C26—H26B0.9600
C11—H11A0.9700C26—H26C0.9600
C23—O1—C3118.5 (3)C11—C12—H12A109.4
C19—N1—C22115.8 (4)C13—C12—H12B109.4
C2—C1—C10114.3 (3)C11—C12—H12B109.4
C2—C1—H1A108.7H12A—C12—H12B108.0
C10—C1—H1A108.7C17—C13—C12118.1 (3)
C2—C1—H1B108.7C17—C13—C1499.4 (2)
C10—C1—H1B108.7C12—C13—C14106.5 (2)
H1A—C1—H1B107.6C17—C13—C26108.8 (3)
C3—C2—C1110.6 (3)C12—C13—C26111.1 (3)
C3—C2—H2A109.5C14—C13—C26112.4 (3)
C1—C2—H2A109.5C8—C14—C15123.0 (3)
C3—C2—H2B109.5C8—C14—C13115.0 (2)
C1—C2—H2B109.5C15—C14—C13103.4 (3)
H2A—C2—H2B108.1C8—C14—H14A104.6
O1—C3—C2109.9 (3)C15—C14—H14A104.6
O1—C3—C4106.6 (3)C13—C14—H14A104.6
C2—C3—C4110.9 (3)C16—C15—C14100.1 (3)
O1—C3—H3A109.8C16—C15—H15A111.7
C2—C3—H3A109.8C14—C15—H15A111.7
C4—C3—H3A109.8C16—C15—H15B111.7
C5—C4—C3112.1 (3)C14—C15—H15B111.7
C5—C4—H4A109.2H15A—C15—H15B109.5
C3—C4—H4A109.2C17—C16—C15112.4 (3)
C5—C4—H4B109.2C17—C16—H16A123.8
C3—C4—H4B109.2C15—C16—H16A123.8
H4A—C4—H4B107.9C16—C17—C18125.4 (3)
C6—C5—C4121.6 (3)C16—C17—C13109.2 (3)
C6—C5—C10122.4 (3)C18—C17—C13125.3 (3)
C4—C5—C10115.9 (3)C20—C18—C19115.9 (3)
C5—C6—C7126.0 (3)C20—C18—C17121.6 (3)
C5—C6—H6A117.0C19—C18—C17122.5 (3)
C7—C6—H6A117.0N1—C19—C18125.7 (4)
C6—C7—C8113.1 (3)N1—C19—H19A117.1
C6—C7—H7A109.0C18—C19—H19A117.1
C8—C7—H7A109.0C21—C20—C18119.8 (4)
C6—C7—H7B109.0C21—C20—H20A120.1
C8—C7—H7B109.0C18—C20—H20A120.1
H7A—C7—H7B107.8C22—C21—C20118.4 (4)
C14—C8—C7111.2 (2)C22—C21—H21A120.8
C14—C8—C9108.1 (2)C20—C21—H21A120.8
C7—C8—C9109.8 (3)N1—C22—C21124.3 (4)
C14—C8—H8A109.3N1—C22—H22A117.8
C7—C8—H8A109.3C21—C22—H22A117.8
C9—C8—H8A109.3O2—C23—O1122.6 (5)
C11—C9—C8112.8 (2)O2—C23—C24125.5 (5)
C11—C9—C10113.0 (2)O1—C23—C24111.8 (5)
C8—C9—C10113.0 (2)C23—C24—H24A109.5
C11—C9—H9A105.7C23—C24—H24B109.5
C8—C9—H9A105.7H24A—C24—H24B109.5
C10—C9—H9A105.7C23—C24—H24C109.5
C5—C10—C25108.9 (3)H24A—C24—H24C109.5
C5—C10—C1107.9 (3)H24B—C24—H24C109.5
C25—C10—C1109.4 (3)C10—C25—H25A109.5
C5—C10—C9109.9 (2)C10—C25—H25B109.5
C25—C10—C9111.7 (3)H25A—C25—H25B109.5
C1—C10—C9108.8 (2)C10—C25—H25C109.5
C9—C11—C12114.6 (2)H25A—C25—H25C109.5
C9—C11—H11A108.6H25B—C25—H25C109.5
C12—C11—H11A108.6C13—C26—H26A109.5
C9—C11—H11B108.6C13—C26—H26B109.5
C12—C11—H11B108.6H26A—C26—H26B109.5
H11A—C11—H11B107.6C13—C26—H26C109.5
C13—C12—C11111.1 (2)H26A—C26—H26C109.5
C13—C12—H12A109.4H26B—C26—H26C109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C21—H21A···O2i0.932.703.520 (6)147
Symmetry code: (i) x+1/2, y+2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C21—H21A···O2i0.932.703.520 (6)147
Symmetry code: (i) x+1/2, y+2, z+1/2.
 

Acknowledgements

The work was supported financially by Hangzhou Jiuyuan Gene Engineering Co. Ltd, Hangzhou, Zhejiang, China.

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Volume 71| Part 3| March 2015| Pages o146-o147
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