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Racemic threo-3-hydroxy-2,3-diphenyl­propionic acid, C15H14O3, (I), crystallizes from ethyl acetate as a conglomerate of separate (+)- and (-)-crystals. The geometries of (I) and its methyl ester are compared. Reduction of (I) gives threo-1,2-diphenyl-1,3-propane­diol. The synthesis of threo forms of 1,2-diaryl-1,3-propane­diols via 2,3-diaryl-3-hydroxy­propionic acids is discussed.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106046026/sk3072sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106046026/sk3072Isup2.hkl
Contains datablock I

CCDC reference: 633173

Comment top

The stereochemistry of the threo, (I), and erythro forms of 3-hydroxy-2,3-diphenylpropionic acid was elucidated by Zimmerman & Traxler (1957). Reaction of benzaldehyde with α-lithiated phenylacetic acid gives a mixture of the diastereomers in high yield (Lundquist & Stomberg, 1987). The threo isomer (I) predominates in the product and could be obtained in pure state by fractional crystallization from ethyl acetate. The crystal structure of (I) reported in this paper confirms its steric assignment. 1,2-Bis(4-benzyloxy-3-methoxyphenyl)-3-hydroxypropionic acid has been prepared in an analogous synthesis (Berndtsson et al., 1980). The threo form, (II), predominates in the reaction product. Reduction of (I) gives the threo form of 1,2-diphenyl-1,3-propanediol, (III) (Lundquist & Stomberg, 1987). Analogously, reduction of (II) gives the threo form of the 1,2-diaryl-1,3-propanediol (IV) (Berndtsson et al., 1980). Removal of the benzylic groups by catalytic hydrogenation gives the threo form of 1,2-bis(4-hydroxy-3-methoxyphenyl)-1,3-propanediol, (V) (Berndtsson et al., 1980). This compound is an appropriate model compound for threo forms of lignin structures of the 1,2-diaryl-1,3-propanediol type. The results described above suggest that the synthetic method involving an α-lithiated carboxylic acid intermediate is generally applicable to the synthesis of threo forms of lignin models of the 1,2-diaryl-1,3-propanediol type. Threo selectivity was also observed in a synthesis of 1,2-diaryl-1,3-propanediols involving an intermediate methyl ester of a 2,3-diaryl-3-hydroxypropionic acid (Nakatsubo & Higuchi, 1975). Hydroboration of (E)-2,3-bis(3,4-dimethoxyphenyl)propenoic acid gives the threo form of the 1,2-diaryl-1,3-propanediol lignin model 1,2-bis(3,4-dimethoxyphenyl)-1,3-propanediol, (VI) (Li et al., 1997). This exemplifies an additional synthetic method for the preparation of threo forms of this type of lignin model. It is noteworthy that 1H NMR data for the CH2 group in the diacetate of (VI) calculated based on substituent effects (Ede & Ralph, 1996) deviate significantly from experimental data (Li et al., 1993). This discrepancy may be related to the vicinity of the aromatic groups in this type of compounds.

A perspective drawing and the atom-numbering of (I) are shown in Fig.1. The absolute configuration could not be determined and the configuration R on C7 and S on C8 was adopted. A search of the Cambridge Structural Database (CSD; Version 5.27 of November 2005, plus three updates; Allen, 2002) for related compounds [search fragment: Ar-CHOH-CH(COO)-Ar', Ar and Ar' are aromatic groups] gave just two hits, one of them (CSD refcode NEWSUD: Ahn et al., 1998) with a bulky binaphtalene substituent. The second was the methyl ester of (I), which exists as rac-(R,S) crystals (YUYKAE; Kolev et al., 1995). Geometric details of (I) and its methyl ester are given in Table 1. Disregarding the differently oriented carboxyl and methoxycarboxyl groups, the overall geometries are quite similar (Fig. 2).

There are both strong hydrogen bonds of O–H···O type (Fig.3.) and weak hydrogen bonds of C–H···O type present in the crystal structure of (I) (Table 2). On the first-level graph-set, defined by Bernstein et al. (1995) and Grell et al. (1999), C(6) chains, formed by hydrogen bonds a and b, a C(7) chain formed by hydrogen bonds c, and an S(6) string formed by the intramolecular hydrogen bond d were identified. On the second-level graph-set, R22(12) (a,b), R22(13) (a,c) and R22(9) (b,c) rings and C22(6) (a,b), C12(7) (a,c) and C22(13) (b,c) chains could be recognized. The assignments of graph-set descriptors were performed using PLUTO as described by Motherwell et al. (1999).

Experimental top

threo-3-Hydroxy-1,2-diphenylpropionic acid, (I), was prepared according to the method of Lundquist & Stomberg (1987). Crystals of (I) were obtained from ethyl acetate (m.p. 451–454 K).

Refinement top

C-bound H atoms were constrained to an ideal geometry using an appropriate riding model with Uiso(H) fixed at 1.2Ueq(C) (C—H = 0.93 and 0.98 Å). For the hydroxy groups, the O—H distances (0.82 Å) and C—O—H angles (109.5°) were kept fixed, while the torsion angles were allowed to refine with the starting positions based on the circular Fourier synthesis; for these H atoms, Uiso(H) values were fixed at 1.5Ueq(O).

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A perspective drawing of (I), showing the atom numbering. Atomic displacement ellipsoids are shown at the 30% probability level.
[Figure 2] Fig. 2. A projection of overlayed structures of (I) in red and of (±)-threo-3-hydroxy-2,3-diphenylpropanoic acid methyl ester (Kolev et al., 1995) in blue.
[Figure 3] Fig. 3. The hydrogen-bonding scheme, viewed along the c axis. For symmetry codes see Table 2.
rac-threo-3-hydroxy-1,2-diphenylpropionic acid top
Crystal data top
C15H14O3Dx = 1.312 Mg m3
Mr = 242.26Melting point = 451–454 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 3842 reflections
a = 5.8107 (2) Åθ = 2.0–25.4°
b = 13.6635 (3) ŵ = 0.09 mm1
c = 15.4507 (5) ÅT = 296 K
V = 1226.70 (6) Å3Needle, colourless
Z = 40.35 × 0.09 × 0.09 mm
F(000) = 512
Data collection top
Siemens SMART CCD area-detector
diffractometer
1325 independent reflections
Radiation source: fine-focus sealed tube1133 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.046
ω scansθmax = 25.4°, θmin = 2.0°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
h = 76
Tmin = 0.832, Tmax = 0.992k = 1516
9335 measured reflectionsl = 1818
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)] = 0.035H-atom parameters constrained
wR(F2) = 0.089 w = 1/[σ2(Fo2) + (0.0499P)2 + 0.2342P]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
1325 reflectionsΔρmax = 0.14 e Å3
166 parametersΔρmin = 0.13 e Å3
0 restraintsExtinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.045 (5)
Crystal data top
C15H14O3V = 1226.70 (6) Å3
Mr = 242.26Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 5.8107 (2) ŵ = 0.09 mm1
b = 13.6635 (3) ÅT = 296 K
c = 15.4507 (5) Å0.35 × 0.09 × 0.09 mm
Data collection top
Siemens SMART CCD area-detector
diffractometer
1325 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
1133 reflections with I > 2σ(I)
Tmin = 0.832, Tmax = 0.992Rint = 0.046
9335 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.089H-atom parameters constrained
S = 1.01Δρmax = 0.14 e Å3
1325 reflectionsΔρmin = 0.13 e Å3
166 parameters
Special details top

Experimental. Data were collected at room temperature using a Siemens SMART CCD diffractometer. Almost full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 30 s per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Bruker, 2003a). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 3842 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003b).

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
C10.4375 (4)0.02864 (17)0.35263 (15)0.0331 (6)
C20.3611 (5)0.06525 (19)0.33409 (17)0.0441 (7)
H20.22200.08700.35680.053*
C30.4903 (6)0.1268 (2)0.28204 (19)0.0564 (9)
H30.43840.18990.27040.068*
C40.6944 (6)0.0950 (2)0.24773 (18)0.0568 (8)
H40.78120.13660.21300.068*
C50.7711 (6)0.0016 (2)0.26453 (17)0.0524 (7)
H50.90880.02000.24050.063*
C60.6441 (5)0.06006 (19)0.31701 (16)0.0412 (6)
H60.69730.12290.32850.049*
C70.3037 (4)0.09310 (16)0.41360 (15)0.0325 (6)
H70.14500.06930.41730.039*
C80.4109 (4)0.09415 (17)0.50564 (15)0.0328 (6)
H80.56920.11800.49970.039*
C90.2847 (4)0.16612 (17)0.56292 (15)0.0331 (6)
C100.4242 (4)0.00700 (18)0.54641 (15)0.0347 (6)
C110.6187 (5)0.0640 (2)0.53290 (18)0.0477 (7)
H110.74120.03890.50110.057*
C120.6317 (6)0.1581 (2)0.5665 (2)0.0613 (9)
H120.76080.19640.55550.074*
C130.4565 (7)0.1948 (2)0.6154 (2)0.0628 (9)
H130.46740.25760.63840.075*
C140.2634 (6)0.1390 (2)0.6308 (2)0.0603 (9)
H140.14400.16350.66450.072*
C150.2488 (5)0.04553 (19)0.59548 (19)0.0460 (7)
H150.11750.00830.60530.055*
O10.3027 (3)0.19214 (11)0.38143 (11)0.0366 (4)
H10.17080.21350.38210.055*
O20.0588 (3)0.16445 (13)0.55190 (12)0.0398 (5)
H2A0.00010.20930.57940.060*
O30.3773 (3)0.22046 (13)0.61427 (12)0.0442 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0345 (14)0.0328 (13)0.0319 (12)0.0015 (11)0.0040 (11)0.0011 (10)
C20.0484 (17)0.0392 (15)0.0446 (15)0.0021 (13)0.0066 (13)0.0022 (11)
C30.081 (2)0.0372 (16)0.0513 (17)0.0095 (16)0.0150 (17)0.0126 (14)
C40.067 (2)0.0612 (19)0.0420 (15)0.0214 (18)0.0020 (17)0.0152 (14)
C50.0486 (17)0.0645 (18)0.0440 (15)0.0094 (15)0.0070 (14)0.0022 (14)
C60.0419 (15)0.0418 (14)0.0398 (14)0.0015 (13)0.0037 (13)0.0055 (12)
C70.0290 (12)0.0308 (12)0.0378 (13)0.0019 (11)0.0001 (11)0.0022 (10)
C80.0294 (12)0.0354 (12)0.0336 (13)0.0012 (11)0.0027 (11)0.0000 (10)
C90.0330 (14)0.0319 (13)0.0345 (12)0.0010 (11)0.0034 (11)0.0065 (11)
C100.0362 (14)0.0357 (13)0.0322 (12)0.0032 (11)0.0043 (12)0.0001 (10)
C110.0450 (16)0.0526 (16)0.0453 (15)0.0141 (14)0.0037 (13)0.0043 (13)
C120.065 (2)0.0534 (18)0.0655 (19)0.0250 (17)0.0031 (18)0.0033 (16)
C130.079 (2)0.0363 (16)0.073 (2)0.0055 (17)0.000 (2)0.0113 (16)
C140.061 (2)0.0446 (17)0.075 (2)0.0016 (16)0.0099 (18)0.0129 (15)
C150.0449 (16)0.0360 (13)0.0571 (17)0.0040 (13)0.0071 (14)0.0044 (12)
O10.0331 (9)0.0327 (9)0.0441 (9)0.0022 (7)0.0011 (9)0.0042 (7)
O20.0307 (10)0.0414 (10)0.0473 (11)0.0041 (8)0.0024 (8)0.0064 (8)
O30.0399 (10)0.0452 (10)0.0476 (10)0.0054 (9)0.0037 (10)0.0136 (9)
Geometric parameters (Å, º) top
C1—C61.389 (4)C8—H80.9800
C1—C21.387 (4)C9—O31.213 (3)
C1—C71.506 (3)C9—O21.323 (3)
C2—C31.385 (4)C10—C151.375 (4)
C2—H20.9300C10—C111.389 (4)
C3—C41.370 (5)C11—C121.389 (4)
C3—H30.9300C11—H110.9300
C4—C51.376 (4)C12—C131.364 (5)
C4—H40.9300C12—H120.9300
C5—C61.383 (4)C13—C141.378 (5)
C5—H50.9300C13—H130.9300
C6—H60.9300C14—C151.391 (4)
C7—O11.442 (3)C14—H140.9300
C7—C81.553 (3)C15—H150.9300
C7—H70.9800O1—H10.8200
C8—C91.513 (3)O2—H2A0.8200
C8—C101.521 (3)
C6—C1—C2118.7 (2)C9—C8—H8107.1
C6—C1—C7120.9 (2)C10—C8—H8107.1
C2—C1—C7120.3 (2)C7—C8—H8107.1
C1—C2—C3120.5 (3)O3—C9—O2122.3 (2)
C1—C2—H2119.7O3—C9—C8124.4 (2)
C3—C2—H2119.7O2—C9—C8113.2 (2)
C4—C3—C2120.1 (3)C15—C10—C11118.1 (2)
C4—C3—H3120.0C15—C10—C8122.6 (2)
C2—C3—H3120.0C11—C10—C8119.3 (2)
C3—C4—C5120.1 (3)C10—C11—C12120.5 (3)
C3—C4—H4119.9C10—C11—H11119.8
C5—C4—H4119.9C12—C11—H11119.8
C4—C5—C6120.2 (3)C13—C12—C11120.5 (3)
C4—C5—H5119.9C13—C12—H12119.8
C6—C5—H5119.9C11—C12—H12119.8
C5—C6—C1120.4 (3)C12—C13—C14120.0 (3)
C5—C6—H6119.8C12—C13—H13120.0
C1—C6—H6119.8C14—C13—H13120.0
O1—C7—C1109.60 (19)C13—C14—C15119.4 (3)
O1—C7—C8107.99 (18)C13—C14—H14120.3
C1—C7—C8111.8 (2)C15—C14—H14120.3
O1—C7—H7109.1C10—C15—C14121.5 (3)
C1—C7—H7109.1C10—C15—H15119.2
C8—C7—H7109.1C14—C15—H15119.2
C9—C8—C10111.91 (19)C7—O1—H1109.5
C9—C8—C7110.33 (19)C9—O2—H2A109.5
C10—C8—C7113.03 (18)
C6—C1—C2—C30.9 (4)C10—C8—C9—O393.9 (3)
C7—C1—C2—C3176.2 (2)C7—C8—C9—O3139.3 (2)
C1—C2—C3—C40.6 (4)C10—C8—C9—O286.0 (3)
C2—C3—C4—C50.3 (4)C7—C8—C9—O240.8 (3)
C3—C4—C5—C60.8 (4)C9—C8—C10—C1535.8 (3)
C4—C5—C6—C10.5 (4)C7—C8—C10—C1589.5 (3)
C2—C1—C6—C50.4 (4)C9—C8—C10—C11145.2 (2)
C7—C1—C6—C5176.7 (2)C7—C8—C10—C1189.5 (3)
C6—C1—C7—O142.6 (3)C15—C10—C11—C121.6 (4)
C2—C1—C7—O1140.3 (2)C8—C10—C11—C12177.5 (3)
C6—C1—C7—C877.1 (3)C10—C11—C12—C132.0 (5)
C2—C1—C7—C899.9 (3)C11—C12—C13—C141.0 (5)
O1—C7—C8—C954.5 (2)C12—C13—C14—C150.5 (5)
C1—C7—C8—C9175.2 (2)C11—C10—C15—C140.2 (4)
O1—C7—C8—C10179.3 (2)C8—C10—C15—C14178.8 (3)
C1—C7—C8—C1058.7 (3)C13—C14—C15—C100.9 (5)

Experimental details

Crystal data
Chemical formulaC15H14O3
Mr242.26
Crystal system, space groupOrthorhombic, P212121
Temperature (K)296
a, b, c (Å)5.8107 (2), 13.6635 (3), 15.4507 (5)
V3)1226.70 (6)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.35 × 0.09 × 0.09
Data collection
DiffractometerSiemens SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.832, 0.992
No. of measured, independent and
observed [I > 2σ(I)] reflections
9335, 1325, 1133
Rint0.046
(sin θ/λ)max1)0.603
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.089, 1.01
No. of reflections1325
No. of parameters166
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.14, 0.13

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SAINT and SADABS (Sheldrick, 2003), SHELXTL (Bruker, 2003), SHELXTL, DIAMOND (Brandenburg, 2006).

Hydrogen-bonding geometry (Å, °) top
LabelD—H···AD—HH···AD···AD—H···A
aO1—H1···O3i0.821.932.746 (2)173
bO2—H2A···O1i0.821.872.667 (2)164
cC6—H6···O3ii0.932.543.458 (3)169
dC15—H15···O20.932.523.147 (3)125
Symmetry codes: (i) x − 1/2, −y + 1/2, −z + 1; (ii) x + 1/2, −y + 1/2,-z + 1.
Selected geometrical parameters (Å,°) for compound (I) and its methyl ester (YUYKAE: Kolev et al., 1995) top
Bond(I)YUYKAE
C1-C71.506 (3)1.514 (3)
O1-C71.442 (3)1.427 (3)
C7-C81.553 (3)1.530 (3)
C8-C101.521 (3)1.515 (3)
C8-C91.513 (3)1.515 (3)
O2-C91.323 (3)1.326 (3)
O3-C91.213 (3)1.205 (2)
Angle
C1-C7-C8111.8 (2)110.0 (2)
C1-C7-O1109.60 (19)112.2 (2)
O1-C7-C8107.99 (18)106.8 (2)
C7-C8-C10113.03 (18)112.8 (2)
C7-C8-C9110.33 (19)112.7 (2)
C9-C8-C10111.91 (19)108.9 (2)
C8-C9-O2113.2 (2)110.3 (2)
C8-C9-O3124.4 (2)126.5 (2)
O2-C9-O3122.3 (2)123.1 (2)
Torsion angle
C1-C7-C8-C10-58.7 (3)-63.4 (2)
C1-C7-C8-C9175.2 (2)172.7 (2)
O1-C7-C8-C10-179.3 (2)175.8 (2)
O2-C9-C8-C740.8 (3)-149.3 (3)
O3-C9-C8-C7-139.3 (2)34.7 (3)
O2-C9-C8-C10-86.0 (3)84.7 (3)
O3-C9-C8-C1093.9 (3)-91.3 (3)
Dihedral angle between aromatic rings42.0 (1)53.0 (1)
 

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