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

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ISSN: 2414-3146

rac-N-(4-Eth­­oxy­phen­yl)-3-hy­dr­oxy­butanamide

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aDepartment of Environmental Toxicology, Southern University and A&M College, Baton Rouge, LA 70813, USA, and bDepartment of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
*Correspondence e-mail: rao_uppu@subr.edu

Edited by L. Van Meervelt, Katholieke Universiteit Leuven, Belgium (Received 7 March 2023; accepted 8 March 2023; online 15 March 2023)

In the title compound, racemic bucetin [systematic name: N-(4-eth­oxy­phen­yl)-3-hydroxy­butanamide], C12H17NO3, the mol­ecule is in an extended conformation as illustrated by the C—O—C—C torsion angle [170.14 (15)°] in the eth­oxy group and the subsequent C—N—C—C [−177.24 (16)°], N—C—C—C [170.08 (15)°] and C—C—C—C [171.41 (15)°] torsion angles in the butanamide chain. In the crystal, the O—H group donates an inter­molecular O—H⋯O hydrogen bond to the amide carbonyl oxygen atom and also accepts an inter­molecular N—H⋯O hydrogen bond from an adjacent N—H group. The former forms 12-membered dimeric rings about inversion centers, and the latter form chains in the [001] direction. The overall hydrogen-bonded network is two-dimensional, with no propagation in the [100] direction.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

N-(4-Eth­oxy­phen­yl)-3-hydro­butanamide, popularly known as bucetin, is an analgesic and anti­pyric that is similar in structure to phenacetin [N-(4-eth­oxy­phen­yl)acetamide]. Once thought to be a better substitute for phenacetin (Ehrhart et al., 1965[Ehrhart, G., Lindner, E. & Häussler, A. (1965). Arzneimittelforschung, 15, 727-738.]; Ehrhart & Ott, 1958[Ehrhart, G. & Ott, H. (1958). US Patent 2830087]), bucetin was introduced into the markets in Germany but was soon withdrawn from use because of renal toxicity and risk of carcinogenesis (Fung et al., 2001[Fung, M., Thornton, A., Mybeck, K., Wu, J. H. H., Hornbuckle, K. & Muniz, E. (2001). Ther. Innov. Regul. Sci, 35, 293-317.]; Togei et al., 1987[Togei, K., Sano, N., Maeda, T., Shibata, M. & Otsuka, H. (1987). J. Natl Cancer Inst. 79, 1151-1158.]). The renal toxicity of bucetin, renal papillary necrosis, is similar in nature to that induced by phenacetin but is somewhat less pronounced, presumably due to differences in the rates of de­acyl­ation by microsomal enzymes leading to the formation of 4-eth­oxy­aniline (Nohmi et al., 1984[Nohmi, T., Yoshikawa, K., Ishidate, M. Jr, Hiratsuka, A. & Watabe, T. (1984). Chem. Pharm. Bull. 32, 4525-4531.]). Thus, the renal papillary necrosis by phenacetin and bucetin appears to be a manifestation of the formation of 4-eth­oxy­aniline and the subsequent inhibitory action(s) of this putative metabolite (or its hy­droxy­lated and/or autooxidation products, N-(4-eth­oxy­phen­yl)hydroxyl­amine and 1-eth­oxy-4-nitroso­benzene) on PGE2 synthesis and a possible reduction of COX-2 expression (Camus et al., 1982[Camus, A. M., Friesen, M., Croisy, A. & Bartsch, H. (1982). Cancer Res. 42, 3201-3208.]; Goodin et al., 2002[Goodin, M. G., Walker, R. J. & Rosengren, R. J. (2002). Res. Commun. Mol. Pathol. Pharmacol. 111, 153-166.]; Kankuri et al., 2003[Kankuri, E., Solatunturi, E. & Vapaatalo, H. (2003). Thromb. Res. 110, 299-303.]; Wirth et al., 1982[Wirth, P. J., Alewood, P., Calder, I. & Thorgeirsson, S. S. (1982). Carcinogenesis, 3, 167-170.]).

Previous studies from our laboratory and elsewhere have shown that celluar oxidants, such as per­oxy­nitrite/per­oxy­nitrous acid and hypochlorite/hypo­chlorous acid, can constitute an important pathway for non-enzymatic bio­transformation of N-(4-hy­droxy­phen­yl)acetamide (Bedner & MacCrehan, 2006[Bedner, M. & MacCrehan, W. A. (2006). Environ. Sci. Technol. 40, 516-522.]; Uppu & Martin, 2004[Uppu, R. M. & Martin, R. J. (2004). The Toxicologist (supplement to Toxicol. Sci.) 84, 319.]; Whiteman et al., 1996[Whiteman, M., Kaur, H. & Halliwell, B. (1996). Ann. Rheum. Dis. 55, 383-387.]), apocynin (Gernapudi et al., 2009[Gernapudi, R., Babu, S., Raghavamenon, A. C. & Uppu, R. M. (2009). FASEB J. 23 (S1), LB397.]), clozapine (Frimat et al., 1997[Frimat, B., Gressier, B., Odou, P., Brunet, C., Dine, T., Luycky, M., Cazin, M. & Cazin, J. C. (1997). Fundam. Clin. Pharmacol. 11, 267-274.]; Uppu et al., 2005[Uppu, R. M., Sathishkumar, K. & Perumal, T. E. (2005). Free Radic. Biol. Med. 39 (S1), S15.]), and certain other xenobiotics (Babu et al., 2012[Babu, S., Vellore, N. A., Kasibotla, A. V., Dwayne, H. J., Stubblefield, M. A. & Uppu, R. M. (2012). Biochem. Biophys. Res. Commun. 426, 215-220.]; Ju & Uetrecht, 1998[Ju, C. & Uetrecht, J. P. (1998). Drug Metab. Dispos. 26, 676-680.]; Rattay & Benndorf, 2021[Rattay, B. & Benndorf, R. A. (2021). Front. Pharamcol. 12, x727717.]). We believe that the above referenced oxidants may also be involved in the biotransformation of bucetin, leading to the formation of hy­droxy­lated, chlorinated, and nitrated products and thus contribute to the toxicity. To address this and to better understand the mechanisms of toxicity of bucetin and phenacetin and its congeners, we determined the crystal structure of racemic bucetin.

The mol­ecular structure of the title compound, racemic bucetin, is shown in Fig. 1[link]. The mol­ecule is in an extended conformation as illustrated by torsion angle C4—O1—C11—C12 [170.14 (15)°] in the eth­oxy group and torsion angles C1—N1—C7—C8 [−177.24 (16)°], N1—C7—C8—C9 [170.08 (15)°] and C7—C8—C9—C10 [171.41 (15)°] in the butanamide chain. In the arbitrarily chosen asymmetric molecule, atom C9 has an R configuration, but crystal symmetry generates a racemic mixture.

[Figure 1]
Figure 1
Mol­ecular structure of N-(4-eth­oxy­phen­yl)-3-hy­droxy­butanamide with displacement ellipsoids drawn at the 50% probability level.

As shown in Fig. 2[link], the OH group donates an inter­molecular hydrogen bond to the amide carbonyl oxygen atom and accepts an inter­molecular hydrogen bond from an adjacent N—H group. The donor–acceptor separations for these hydrogen bonds are 2.7268 (17) Å for O—H⋯O(−x + 1, −y + 1, −z + 2) and 2.8611 (19) Å for N—H⋯O(x, −y + [{1\over 2}], z − [{1\over 2}]). The former thus forms 12-membered dimeric rings about inversion centers, and the latter form chains in the [001] direction. The overall hydrogen-bonded network is two-dimensional, with no propagation in the [100] direction. The packing in the unit cell is shown in Fig. 3[link] and includes also C—H⋯O inter­actions (Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H3O⋯O2i 0.89 (2) 1.85 (2) 2.7268 (17) 167 (2)
N1—H1N⋯O3ii 0.88 (2) 1.99 (2) 2.8611 (19) 169.7 (19)
C2—H2⋯O2 0.95 2.32 2.908 (2) 119
C3—H3A⋯O1iii 0.95 2.60 3.482 (2) 154
C6—H6⋯O2ii 0.95 2.65 3.468 (2) 145
C6—H6⋯O3ii 0.95 2.48 3.269 (2) 141
C8—H8B⋯O2iv 0.99 2.58 3.553 (2) 167
Symmetry codes: (i) [-x+1, -y+1, -z+2]; (ii) [x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (iii) [-x+2, -y+1, -z+1]; (iv) [-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}].
[Figure 2]
Figure 2
The hydrogen bonding in the packing of N-(4-eth­oxy­phen­yl)-3-hy­droxy­butanamide.
[Figure 3]
Figure 3
Crystal packing of the title compound N-(4-eth­oxy­phen­yl)-3-hy­droxy­butanamide.

Given the current understanding that de-acyl­ation constitutes an important step in the expression of renal toxicity (Kankuri et al., 2003[Kankuri, E., Solatunturi, E. & Vapaatalo, H. (2003). Thromb. Res. 110, 299-303.]; Nohmi et al., 1984[Nohmi, T., Yoshikawa, K., Ishidate, M. Jr, Hiratsuka, A. & Watabe, T. (1984). Chem. Pharm. Bull. 32, 4525-4531.]; Taxak et al., 2013[Taxak, N., Chaitanya Prasad, K. & Bharatam, P. V. (2013). Comput. Theor. Chem. 1007, 48-56.]), and the fact that the acyl group in bucetin (3-hy­droxy­butyr­yl) is much larger in size compared to the acetyl group in phenacetin and its congeners and has a chiral center, the information on the crystal structure of bucetin presented here may help in the development of analgesics with little or no renal toxicity.

Synthesis and crystallization

The title compound, C12H17NO3 (bucetin; CAS No. 1083–57-4) was obtained from Sigma-Aldrich, St. Louis, MO and was used without further purification. Single crystals of racemic bucetin were prepared by slow cooling of a nearly saturated solution of bucetin in boiling deionized water.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C12H17NO3
Mr 223.26
Crystal system, space group Monoclinic, P21/c
Temperature (K) 100
a, b, c (Å) 12.2343 (4), 9.6404 (3), 9.9098 (3)
β (°) 93.295 (2)
V3) 1166.86 (6)
Z 4
Radiation type Cu Kα
μ (mm−1) 0.75
Crystal size (mm) 0.14 × 0.14 × 0.01
 
Data collection
Diffractometer Bruker Kappa APEXII CCD DUO
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.832, 0.993
No. of measured, independent and observed [I > 2σ(I)] reflections 14229, 2139, 1739
Rint 0.061
(sin θ/λ)max−1) 0.603
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.045, 0.116, 1.06
No. of reflections 2139
No. of parameters 153
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.40, −0.23
Computer programs: APEX2 and SAINT (Bruker, 2016[Bruker (2016). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014/5 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2017/1 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), Mercury (Macrae et al., 2020[Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226-235.]), and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017/1 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: publCIF (Westrip, 2010).

N-(4-Ethoxyphenyl)-3-hydroxybutanamide top
Crystal data top
C12H17NO3F(000) = 480
Mr = 223.26Dx = 1.271 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54184 Å
a = 12.2343 (4) ÅCell parameters from 3666 reflections
b = 9.6404 (3) Åθ = 3.6–68.5°
c = 9.9098 (3) ŵ = 0.75 mm1
β = 93.295 (2)°T = 100 K
V = 1166.86 (6) Å3Plate, colourless
Z = 40.14 × 0.14 × 0.01 mm
Data collection top
Bruker Kappa APEXII CCD DUO
diffractometer
2139 independent reflections
Radiation source: IµS microfocus1739 reflections with I > 2σ(I)
QUAZAR multilayer optics monochromatorRint = 0.061
φ and ω scansθmax = 68.5°, θmin = 3.6°
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
h = 1414
Tmin = 0.832, Tmax = 0.993k = 1111
14229 measured reflectionsl = 1111
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.045H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.116 w = 1/[σ2(Fo2) + (0.0542P)2 + 0.4983P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max < 0.001
2139 reflectionsΔρmax = 0.40 e Å3
153 parametersΔρmin = 0.23 e Å3
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. All H atoms were located in difference maps and those on C were thereafter treated as riding in geometrically idealized positions with C—H distances 0.95 Å for phenyl, 0.98 Å for methyl, 0.99 Å for CH2, and 1.00 Å for methine. Coordinates of the N—H and O—H hydrogen atoms were refined. Uiso(H) values were assigned as 1.2Ueq for the attached atom (1.5 for methyl and OH).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.93903 (10)0.38529 (13)0.33811 (12)0.0251 (3)
O20.56520 (10)0.51646 (12)0.76720 (12)0.0250 (3)
O30.43094 (10)0.37235 (13)0.97956 (12)0.0225 (3)
H3O0.4299 (17)0.421 (2)1.056 (2)0.034*
N10.54676 (12)0.35963 (15)0.59755 (15)0.0214 (3)
H1N0.5043 (17)0.295 (2)0.559 (2)0.026*
C10.64870 (14)0.36976 (17)0.53789 (17)0.0203 (4)
C20.73038 (14)0.46664 (17)0.57328 (17)0.0204 (4)
H20.7201360.5316920.6434450.024*
C30.82674 (14)0.46737 (17)0.50532 (17)0.0214 (4)
H3A0.8822260.5331300.5297740.026*
C40.84298 (14)0.37343 (18)0.40232 (17)0.0211 (4)
C50.76284 (15)0.27562 (18)0.36878 (18)0.0247 (4)
H50.7735530.2096190.2995920.030*
C60.66716 (15)0.27482 (18)0.43681 (18)0.0236 (4)
H60.6126970.2073590.4135410.028*
C70.51039 (14)0.42701 (17)0.70506 (17)0.0204 (4)
C80.39683 (15)0.38164 (18)0.74180 (18)0.0238 (4)
H8A0.3429270.4122400.6695540.029*
H8B0.3946990.2790440.7449560.029*
C90.36269 (15)0.43784 (18)0.87556 (18)0.0237 (4)
H90.3751580.5403410.8786490.028*
C100.24341 (15)0.4077 (2)0.8973 (2)0.0291 (4)
H10A0.2319070.3071610.8994540.044*
H10B0.1974250.4481850.8231740.044*
H10C0.2237480.4483330.9832390.044*
C110.95150 (15)0.29641 (19)0.22356 (19)0.0267 (4)
H11A0.8860160.3026290.1603520.032*
H11B0.9603010.1988520.2534340.032*
C121.05153 (16)0.3435 (2)0.1548 (2)0.0336 (5)
H12A1.0420810.4402950.1261420.050*
H12B1.0617360.2850850.0756330.050*
H12C1.1159100.3359420.2179430.050*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0241 (7)0.0297 (7)0.0221 (7)0.0038 (5)0.0063 (5)0.0055 (5)
O20.0345 (7)0.0209 (7)0.0204 (6)0.0026 (5)0.0082 (5)0.0018 (5)
O30.0279 (7)0.0242 (7)0.0153 (6)0.0032 (5)0.0013 (5)0.0005 (5)
N10.0241 (8)0.0217 (8)0.0186 (8)0.0041 (6)0.0036 (6)0.0017 (6)
C10.0244 (9)0.0196 (9)0.0171 (9)0.0003 (6)0.0026 (7)0.0022 (6)
C20.0266 (9)0.0177 (8)0.0168 (8)0.0010 (7)0.0020 (7)0.0006 (6)
C30.0250 (9)0.0204 (9)0.0188 (9)0.0035 (7)0.0004 (7)0.0002 (6)
C40.0217 (9)0.0241 (9)0.0177 (9)0.0000 (7)0.0029 (7)0.0025 (7)
C50.0302 (10)0.0227 (9)0.0219 (9)0.0027 (7)0.0070 (7)0.0054 (7)
C60.0282 (9)0.0209 (9)0.0222 (9)0.0070 (7)0.0050 (7)0.0032 (7)
C70.0280 (9)0.0167 (8)0.0168 (8)0.0024 (7)0.0024 (7)0.0025 (7)
C80.0261 (10)0.0247 (9)0.0208 (9)0.0002 (7)0.0016 (7)0.0012 (7)
C90.0272 (10)0.0220 (9)0.0220 (9)0.0025 (7)0.0024 (7)0.0029 (7)
C100.0267 (10)0.0327 (10)0.0283 (10)0.0003 (8)0.0053 (8)0.0033 (8)
C110.0304 (10)0.0260 (10)0.0245 (10)0.0005 (7)0.0082 (8)0.0048 (7)
C120.0330 (11)0.0381 (11)0.0312 (11)0.0024 (8)0.0135 (9)0.0070 (8)
Geometric parameters (Å, º) top
O1—C41.373 (2)C6—H60.9500
O1—C111.437 (2)C7—C81.521 (2)
O2—C71.235 (2)C8—C91.513 (2)
O3—C91.435 (2)C8—H8A0.9900
O3—H3O0.89 (2)C8—H8B0.9900
N1—C71.345 (2)C9—C101.515 (3)
N1—C11.414 (2)C9—H91.0000
N1—H1N0.88 (2)C10—H10A0.9800
C1—C61.385 (2)C10—H10B0.9800
C1—C21.398 (2)C10—H10C0.9800
C2—C31.391 (2)C11—C121.505 (3)
C2—H20.9500C11—H11A0.9900
C3—C41.387 (2)C11—H11B0.9900
C3—H3A0.9500C12—H12A0.9800
C4—C51.387 (3)C12—H12B0.9800
C5—C61.384 (2)C12—H12C0.9800
C5—H50.9500
C4—O1—C11116.67 (13)C7—C8—H8A108.7
C9—O3—H3O110.2 (14)C9—C8—H8B108.7
C7—N1—C1129.62 (15)C7—C8—H8B108.7
C7—N1—H1N118.0 (14)H8A—C8—H8B107.6
C1—N1—H1N112.2 (14)O3—C9—C8107.05 (14)
C6—C1—C2118.62 (16)O3—C9—C10109.82 (15)
C6—C1—N1116.18 (15)C8—C9—C10111.86 (15)
C2—C1—N1125.20 (16)O3—C9—H9109.4
C3—C2—C1119.71 (16)C8—C9—H9109.4
C3—C2—H2120.1C10—C9—H9109.4
C1—C2—H2120.1C9—C10—H10A109.5
C4—C3—C2120.94 (16)C9—C10—H10B109.5
C4—C3—H3A119.5H10A—C10—H10B109.5
C2—C3—H3A119.5C9—C10—H10C109.5
O1—C4—C5123.90 (16)H10A—C10—H10C109.5
O1—C4—C3116.69 (15)H10B—C10—H10C109.5
C5—C4—C3119.40 (16)O1—C11—C12107.67 (15)
C6—C5—C4119.55 (16)O1—C11—H11A110.2
C6—C5—H5120.2C12—C11—H11A110.2
C4—C5—H5120.2O1—C11—H11B110.2
C5—C6—C1121.75 (16)C12—C11—H11B110.2
C5—C6—H6119.1H11A—C11—H11B108.5
C1—C6—H6119.1C11—C12—H12A109.5
O2—C7—N1122.49 (16)C11—C12—H12B109.5
O2—C7—C8123.98 (15)H12A—C12—H12B109.5
N1—C7—C8113.52 (15)C11—C12—H12C109.5
C9—C8—C7114.13 (15)H12A—C12—H12C109.5
C9—C8—H8A108.7H12B—C12—H12C109.5
C7—N1—C1—C6172.74 (17)C4—C5—C6—C10.2 (3)
C7—N1—C1—C27.1 (3)C2—C1—C6—C51.4 (3)
C6—C1—C2—C31.1 (2)N1—C1—C6—C5178.76 (16)
N1—C1—C2—C3178.98 (16)C1—N1—C7—O22.5 (3)
C1—C2—C3—C40.2 (3)C1—N1—C7—C8177.24 (16)
C11—O1—C4—C54.6 (2)O2—C7—C8—C99.6 (2)
C11—O1—C4—C3174.53 (15)N1—C7—C8—C9170.08 (15)
C2—C3—C4—O1177.82 (15)C7—C8—C9—O368.25 (18)
C2—C3—C4—C51.4 (3)C7—C8—C9—C10171.41 (15)
O1—C4—C5—C6177.96 (16)C4—O1—C11—C12170.14 (15)
C3—C4—C5—C61.2 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3O···O2i0.89 (2)1.85 (2)2.7268 (17)167 (2)
N1—H1N···O3ii0.88 (2)1.99 (2)2.8611 (19)169.7 (19)
C2—H2···O20.952.322.908 (2)119
C3—H3A···O1iii0.952.603.482 (2)154
C6—H6···O2ii0.952.653.468 (2)145
C6—H6···O3ii0.952.483.269 (2)141
C8—H8B···O2iv0.992.583.553 (2)167
Symmetry codes: (i) x+1, y+1, z+2; (ii) x, y+1/2, z1/2; (iii) x+2, y+1, z+1; (iv) x+1, y1/2, z+3/2.
 

Funding information

The authors acknowledge the support from the National Institutes of Health (NIH) through the National Institute of General Medical Science (NIGMS) grant No. 5 P2O GM103424–20 and the US Department of Education (US DoE; Title III, HBGI Part B grant No. P031B040030). Its contents are solely the responsibility of authors and do not represent the official views of NIH, NIGMS, or US DoE. The upgrade of the diffractometer was made possible by grant No. LEQSF(2011–12)-ENH-TR-01, administered by the Louisiana Board of Regents.

References

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