2,6-Bis[(S)-4-benzyl-4,5-dihydro-1,3-oxazol-2-yl]pyridine

Möller, K.; Junge, K.; Spannenberg, A.; Beller, M.

doi:10.1107/S1600536811014061

organic compounds

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Volume 67| Part 5| May 2011| Page o1181

doi:10.1107/S1600536811014061

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2,6-Bis[(S)-4-benzyl-4,5-dihydro-1,3-oxazol-2-yl]pyridine

Konstanze Möller,^a Kathrin Junge,^a ^* Anke Spannenberg ^a and Matthias Beller ^a

^aLeibniz-Institut für Katalyse e. V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
^*Correspondence e-mail: kathrin.junge@catalysis.de

(Received 31 March 2011; accepted 14 April 2011; online 22 April 2011)

The commercially available title compound, C₂₅H₂₃N₃O₂, has been known since 1993 [Nesper et al. (1993 ). Helv. Chim. Acta, 76, 2239–2249], but has not been structurally characterized until now. In the free ligand, the N atoms of both oxazoline rings point in opposite directions. The phenyl rings make dihedral angles of 30.56 (5) and 84.57 (3)° with the pyridine ring and 72.85 (3)° with each other.

Related literature

For the synthesis, see: Nesper et al. (1993; 1996 ); Schaus & Jacobsen (2000 ); Towers et al. (2003 ); Meng et al. (2005 ); Hui et al. (2006 ). For crystal structures showing the same ligand coordinated to Pd(BF₄)₂ or AgBF₄, see: Nesper et al. (1996); Provent et al. (1997 ). For applications in asymmetric catalysis, see: Desimoni et al. (2003 ); Tse et al. (2006 ).

Experimental

Crystal data

C₂₅H₂₃N₃O₂
M_r = 397.46
Orthorhombic, P 2₁ 2₁ 2₁
a = 7.0184 (2) Å
b = 13.2654 (3) Å
c = 21.5542 (8) Å
V = 2006.74 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 K
0.50 × 0.45 × 0.25 mm

Data collection

Stoe IPDS II diffractometer
38412 measured reflections
5433 independent reflections
4254 reflections with I > 2σ(I)
R_int = 0.045

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.053
S = 0.86
5433 reflections
271 parameters
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2005 ); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811014061/om2419sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811014061/om2419Isup2.hkl

checkCIF report

Comment top

The synthesis of chiral tridentate N,N,N-pyridine-2,6-bisoxazolines (pybox ligands) constitute a useful toolbox for the application in asymmetric catalysis (Desimoni et al., 2003). The title compound was used as part of our ongoing studies (Tse et al., 2006).

In contrast to the complexed ligand (Nesper et al., 1996; Provent et al., 1997) where all N atoms are pointed to the metal to permit coordination, in the free ligand the N atoms of both oxazoline rings point in the opposite direction (Fig. 1). The dihedral angle between the planes defined by C13 - C18 and C20 - C25 is 72.85 (3)°. The phenyl rings (C13 - C18 and C20 - C25) are twisted out of the N1, C4 - C8 plane by an angle of 30.56 (5)° and 84.57 (3)°, respectively. The absolute configuration has been assigned to correspond with that of the known chiral centres of the starting material.

Related literature top

For the synthesis, see: Nesper et al. (1993; 1996); Schaus & Jacobsen (2000); Towers et al. (2003); Meng et al. (2005); Hui et al. (2006). For crystal structures showing the same ligand coordinated to Pd(BF₄)₂ or AgBF₄, see: Nesper et al. (1996); Provent et al. (1997). For applications in asymmetric catalysis, see: Desimoni et al. (2003); Tse et al. (2006).

Experimental top

The synthesis of the commercially available title compound was described by Nesper et al., 1993; Nesper et al., 1996; Schaus & Jacobsen, 2000; Towers et al., 2003; Meng et al., 2005 and Hui et al., 2006. The title compound was purchased from STREM and crystals were grown from a dichloromethane/hexane mixture. The solution was slowly evaporated to dryness for two days and colourless crystals suitable for X-ray analysis were isolated.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.

2,6-Bis[(S)-4-benzyl-4,5-dihydro-1,3-oxazol-2-yl]pyridine top

Crystal data top

C₂₅H₂₃N₃O₂	F(000) = 840
M_r = 397.46	D_x = 1.316 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 7372 reflections
a = 7.0184 (2) Å	θ = 1.8–29.6°
b = 13.2654 (3) Å	µ = 0.09 mm⁻¹
c = 21.5542 (8) Å	T = 150 K
V = 2006.74 (10) Å³	Prism, colourless
Z = 4	0.50 × 0.45 × 0.25 mm

Data collection top

Stoe IPDS II diffractometer	4254 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.045
Graphite monochromator	θ_max = 29.2°, θ_min = 1.8°
ω scans	h = −9→9
38412 measured reflections	k = −18→18
5433 independent reflections	l = −29→29

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.053	H-atom parameters constrained
S = 0.86	w = 1/[σ²(F_o²) + (0.0277P)²] where P = (F_o² + 2F_c²)/3
5433 reflections	(Δ/σ)_max = 0.001
271 parameters	Δρ_max = 0.13 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₂₅H₂₃N₃O₂	V = 2006.74 (10) Å³
M_r = 397.46	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 7.0184 (2) Å	µ = 0.09 mm⁻¹
b = 13.2654 (3) Å	T = 150 K
c = 21.5542 (8) Å	0.50 × 0.45 × 0.25 mm

Data collection top

Stoe IPDS II diffractometer	4254 reflections with I > 2σ(I)
38412 measured reflections	R_int = 0.045
5433 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.053	H-atom parameters constrained
S = 0.86	Δρ_max = 0.13 e Å⁻³
5433 reflections	Δρ_min = −0.18 e Å⁻³
271 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.

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

	x	y	z	U_iso*/U_eq
C1	0.08221 (18)	0.78242 (8)	0.86378 (6)	0.0391 (3)
H1A	0.0477	0.8470	0.8436	0.047*
H1B	0.1124	0.7953	0.9079	0.047*
C2	−0.07905 (16)	0.70557 (7)	0.85760 (5)	0.0307 (2)
H2	−0.1664	0.7274	0.8235	0.037*
C3	0.18890 (16)	0.63775 (7)	0.82495 (5)	0.0271 (2)
C4	0.33449 (15)	0.56927 (7)	0.79877 (5)	0.0271 (2)
C5	0.30631 (16)	0.46567 (7)	0.80236 (5)	0.0320 (2)
H5	0.1993	0.4390	0.8238	0.038*
C6	0.43561 (16)	0.40269 (8)	0.77450 (5)	0.0330 (3)
H6	0.4199	0.3316	0.7762	0.040*
C7	0.58872 (16)	0.44469 (7)	0.74402 (5)	0.0302 (2)
H7	0.6801	0.4029	0.7241	0.036*
C8	0.60768 (16)	0.54896 (7)	0.74277 (5)	0.0261 (2)
C9	0.76549 (16)	0.59535 (7)	0.70744 (4)	0.0274 (2)
C10	1.02808 (19)	0.58556 (8)	0.64867 (6)	0.0410 (3)
H10A	1.0471	0.5688	0.6044	0.049*
H10B	1.1483	0.5731	0.6715	0.049*
C11	0.96205 (16)	0.69563 (8)	0.65652 (5)	0.0307 (2)
H11	0.9089	0.7199	0.6161	0.037*
C12	1.11831 (16)	0.76752 (8)	0.67706 (5)	0.0308 (2)
H12A	1.0595	0.8305	0.6927	0.037*
H12B	1.1903	0.7366	0.7116	0.037*
C13	1.25418 (16)	0.79284 (7)	0.62524 (5)	0.0287 (2)
C14	1.23770 (17)	0.88259 (8)	0.59240 (5)	0.0341 (2)
H14	1.1407	0.9293	0.6032	0.041*
C15	1.36016 (18)	0.90471 (10)	0.54433 (6)	0.0422 (3)
H15	1.3472	0.9665	0.5225	0.051*
C16	1.50168 (19)	0.83760 (9)	0.52768 (6)	0.0415 (3)
H16	1.5855	0.8528	0.4944	0.050*
C17	1.52003 (17)	0.74822 (9)	0.55991 (6)	0.0403 (3)
H17	1.6169	0.7016	0.5488	0.048*
C18	1.39795 (17)	0.72647 (8)	0.60832 (5)	0.0352 (3)
H18	1.4126	0.6650	0.6304	0.042*
C19	−0.19380 (17)	0.69334 (8)	0.91699 (5)	0.0338 (2)
H19A	−0.3029	0.6477	0.9093	0.041*
H19B	−0.1127	0.6623	0.9494	0.041*
C20	−0.26647 (15)	0.79374 (7)	0.93971 (5)	0.0284 (2)
C21	−0.19421 (16)	0.83776 (8)	0.99302 (5)	0.0331 (3)
H21	−0.0999	0.8031	1.0164	0.040*
C22	−0.25669 (18)	0.93129 (8)	1.01295 (5)	0.0369 (3)
H22	−0.2051	0.9603	1.0496	0.044*
C23	−0.39392 (18)	0.98226 (8)	0.97955 (6)	0.0385 (3)
H23	−0.4370	1.0466	0.9930	0.046*
C24	−0.46803 (17)	0.93922 (9)	0.92658 (6)	0.0380 (3)
H24	−0.5632	0.9739	0.9037	0.046*
C25	−0.40519 (17)	0.84613 (8)	0.90655 (5)	0.0329 (2)
H25	−0.4570	0.8175	0.8698	0.040*
N1	0.48293 (13)	0.61177 (6)	0.76977 (4)	0.02706 (19)
N2	0.02005 (14)	0.61231 (6)	0.83845 (4)	0.0311 (2)
N3	0.80484 (13)	0.68788 (6)	0.70200 (4)	0.0307 (2)
O1	0.24182 (12)	0.73528 (5)	0.83241 (3)	0.03401 (18)
O2	0.87275 (12)	0.52786 (5)	0.67492 (4)	0.0402 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0401 (7)	0.0291 (5)	0.0482 (7)	−0.0040 (5)	0.0204 (6)	−0.0039 (5)
C2	0.0318 (6)	0.0266 (5)	0.0337 (6)	−0.0005 (4)	0.0013 (5)	0.0007 (4)
C3	0.0318 (6)	0.0241 (5)	0.0255 (5)	−0.0043 (4)	0.0004 (5)	0.0029 (4)
C4	0.0289 (6)	0.0273 (5)	0.0251 (5)	−0.0027 (4)	−0.0007 (4)	0.0015 (4)
C5	0.0320 (6)	0.0283 (5)	0.0357 (6)	−0.0042 (5)	0.0018 (5)	0.0048 (4)
C6	0.0398 (7)	0.0218 (5)	0.0375 (6)	−0.0016 (5)	−0.0023 (5)	0.0023 (4)
C7	0.0332 (6)	0.0264 (5)	0.0310 (6)	0.0034 (4)	0.0003 (5)	−0.0002 (4)
C8	0.0289 (6)	0.0249 (5)	0.0245 (5)	−0.0005 (4)	−0.0013 (4)	0.0006 (4)
C9	0.0293 (6)	0.0266 (5)	0.0262 (5)	0.0016 (5)	0.0004 (5)	−0.0035 (4)
C10	0.0403 (7)	0.0347 (6)	0.0480 (7)	−0.0067 (5)	0.0162 (6)	−0.0078 (5)
C11	0.0302 (6)	0.0337 (5)	0.0282 (5)	−0.0001 (5)	0.0037 (5)	0.0020 (4)
C12	0.0330 (6)	0.0295 (5)	0.0299 (5)	0.0017 (5)	0.0008 (5)	0.0009 (4)
C13	0.0255 (6)	0.0297 (5)	0.0310 (5)	−0.0031 (4)	−0.0036 (5)	−0.0033 (4)
C14	0.0294 (6)	0.0325 (5)	0.0404 (6)	−0.0010 (5)	−0.0008 (5)	0.0025 (4)
C15	0.0402 (7)	0.0439 (7)	0.0424 (7)	−0.0079 (6)	−0.0013 (6)	0.0104 (5)
C16	0.0349 (7)	0.0544 (7)	0.0351 (6)	−0.0136 (6)	0.0054 (6)	−0.0025 (5)
C17	0.0264 (6)	0.0450 (7)	0.0494 (7)	−0.0017 (5)	0.0039 (6)	−0.0128 (5)
C18	0.0297 (6)	0.0315 (6)	0.0444 (7)	−0.0004 (5)	−0.0007 (5)	−0.0013 (5)
C19	0.0294 (6)	0.0292 (5)	0.0429 (6)	−0.0006 (5)	0.0083 (5)	0.0054 (5)
C20	0.0228 (5)	0.0304 (5)	0.0320 (5)	−0.0024 (5)	0.0068 (5)	0.0071 (4)
C21	0.0263 (6)	0.0406 (6)	0.0323 (6)	0.0000 (5)	0.0018 (5)	0.0084 (4)
C22	0.0376 (7)	0.0416 (6)	0.0314 (5)	−0.0076 (5)	0.0043 (5)	−0.0013 (5)
C23	0.0416 (7)	0.0297 (6)	0.0443 (7)	0.0022 (5)	0.0132 (6)	0.0028 (5)
C24	0.0311 (6)	0.0396 (6)	0.0433 (7)	0.0069 (5)	0.0001 (5)	0.0101 (5)
C25	0.0289 (6)	0.0364 (6)	0.0335 (6)	−0.0028 (5)	−0.0015 (5)	0.0031 (5)
N1	0.0295 (5)	0.0247 (4)	0.0270 (4)	−0.0009 (4)	0.0019 (4)	−0.0001 (3)
N2	0.0297 (5)	0.0268 (4)	0.0370 (5)	−0.0031 (4)	0.0034 (4)	−0.0014 (4)
N3	0.0300 (5)	0.0277 (4)	0.0345 (5)	0.0021 (4)	0.0052 (4)	0.0030 (4)
O1	0.0351 (4)	0.0253 (3)	0.0416 (4)	−0.0049 (3)	0.0136 (4)	−0.0037 (3)
O2	0.0407 (5)	0.0283 (4)	0.0515 (5)	−0.0052 (4)	0.0187 (4)	−0.0111 (3)

Geometric parameters (Å, º) top

C1—O1	1.4503 (14)	C12—C13	1.5065 (15)
C1—C2	1.5290 (17)	C12—H12A	0.9900
C1—H1A	0.9900	C12—H12B	0.9900
C1—H1B	0.9900	C13—C18	1.3879 (15)
C2—N2	1.4781 (14)	C13—C14	1.3899 (14)
C2—C19	1.5211 (15)	C14—C15	1.3778 (16)
C2—H2	1.0000	C14—H14	0.9500
C3—N2	1.2660 (14)	C15—C16	1.3813 (18)
C3—O1	1.3556 (11)	C15—H15	0.9500
C3—C4	1.4790 (14)	C16—C17	1.3801 (17)
C4—N1	1.3394 (13)	C16—H16	0.9500
C4—C5	1.3905 (14)	C17—C18	1.3808 (16)
C5—C6	1.3719 (15)	C17—H17	0.9500
C5—H5	0.9500	C18—H18	0.9500
C6—C7	1.3773 (15)	C19—C20	1.5078 (14)
C6—H6	0.9500	C19—H19A	0.9900
C7—C8	1.3898 (13)	C19—H19B	0.9900
C7—H7	0.9500	C20—C21	1.3852 (15)
C8—N1	1.3415 (13)	C20—C25	1.3934 (15)
C8—C9	1.4784 (15)	C21—C22	1.3843 (16)
C9—N3	1.2636 (13)	C21—H21	0.9500
C9—O2	1.3636 (12)	C22—C23	1.3796 (17)
C10—O2	1.4472 (14)	C22—H22	0.9500
C10—C11	1.5413 (15)	C23—C24	1.3784 (17)
C10—H10A	0.9900	C23—H23	0.9500
C10—H10B	0.9900	C24—C25	1.3806 (15)
C11—N3	1.4796 (14)	C24—H24	0.9500
C11—C12	1.5193 (16)	C25—H25	0.9500
C11—H11	1.0000

O1—C1—C2	104.10 (8)	C11—C12—H12B	109.1
O1—C1—H1A	110.9	H12A—C12—H12B	107.9
C2—C1—H1A	110.9	C18—C13—C14	118.04 (10)
O1—C1—H1B	110.9	C18—C13—C12	120.90 (9)
C2—C1—H1B	110.9	C14—C13—C12	121.05 (10)
H1A—C1—H1B	109.0	C15—C14—C13	120.90 (11)
N2—C2—C19	113.26 (8)	C15—C14—H14	119.6
N2—C2—C1	103.54 (9)	C13—C14—H14	119.6
C19—C2—C1	112.94 (9)	C14—C15—C16	120.44 (11)
N2—C2—H2	109.0	C14—C15—H15	119.8
C19—C2—H2	109.0	C16—C15—H15	119.8
C1—C2—H2	109.0	C17—C16—C15	119.34 (11)
N2—C3—O1	118.92 (10)	C17—C16—H16	120.3
N2—C3—C4	124.80 (9)	C15—C16—H16	120.3
O1—C3—C4	116.24 (9)	C16—C17—C18	120.13 (11)
N1—C4—C5	123.55 (10)	C16—C17—H17	119.9
N1—C4—C3	117.18 (8)	C18—C17—H17	119.9
C5—C4—C3	119.17 (10)	C17—C18—C13	121.14 (10)
C6—C5—C4	118.91 (10)	C17—C18—H18	119.4
C6—C5—H5	120.5	C13—C18—H18	119.4
C4—C5—H5	120.5	C20—C19—C2	110.99 (8)
C5—C6—C7	118.60 (9)	C20—C19—H19A	109.4
C5—C6—H6	120.7	C2—C19—H19A	109.4
C7—C6—H6	120.7	C20—C19—H19B	109.4
C6—C7—C8	119.11 (10)	C2—C19—H19B	109.4
C6—C7—H7	120.4	H19A—C19—H19B	108.0
C8—C7—H7	120.4	C21—C20—C25	118.10 (10)
N1—C8—C7	123.18 (10)	C21—C20—C19	121.19 (10)
N1—C8—C9	116.99 (8)	C25—C20—C19	120.69 (10)
C7—C8—C9	119.74 (9)	C22—C21—C20	121.29 (11)
N3—C9—O2	118.00 (9)	C22—C21—H21	119.4
N3—C9—C8	128.02 (9)	C20—C21—H21	119.4
O2—C9—C8	113.89 (8)	C23—C22—C21	119.90 (11)
O2—C10—C11	103.39 (9)	C23—C22—H22	120.1
O2—C10—H10A	111.1	C21—C22—H22	120.1
C11—C10—H10A	111.1	C24—C23—C22	119.52 (11)
O2—C10—H10B	111.1	C24—C23—H23	120.2
C11—C10—H10B	111.1	C22—C23—H23	120.2
H10A—C10—H10B	109.0	C23—C24—C25	120.59 (11)
N3—C11—C12	112.88 (9)	C23—C24—H24	119.7
N3—C11—C10	103.36 (8)	C25—C24—H24	119.7
C12—C11—C10	114.18 (10)	C24—C25—C20	120.60 (11)
N3—C11—H11	108.7	C24—C25—H25	119.7
C12—C11—H11	108.7	C20—C25—H25	119.7
C10—C11—H11	108.7	C4—N1—C8	116.66 (8)
C13—C12—C11	112.38 (9)	C3—N2—C2	106.35 (8)
C13—C12—H12A	109.1	C9—N3—C11	106.97 (8)
C11—C12—H12A	109.1	C3—O1—C1	104.79 (8)
C13—C12—H12B	109.1	C9—O2—C10	105.64 (8)

Experimental details

Crystal data
Chemical formula	C₂₅H₂₃N₃O₂
M_r	397.46
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	150
a, b, c (Å)	7.0184 (2), 13.2654 (3), 21.5542 (8)
V (Å³)	2006.74 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.50 × 0.45 × 0.25

Data collection
Diffractometer	Stoe IPDS II diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	38412, 5433, 4254
R_int	0.045
(sin θ/λ)_max (Å⁻¹)	0.686

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.053, 0.86
No. of reflections	5433
No. of parameters	271
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.13, −0.18

Computer programs: X-AREA (Stoe & Cie, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008).

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