Comment
The synthesis of heterocyclic systems containing pyrrolidine fragments is an important goal because of the widespread occurrence of such systems both in biologically active natural products and in therapeutic agents. We present here the molecular and supramolecular structures of two compounds prepared for use as intermediates in the synthesis of pyrrolidines using radical cyclization methodology. 2-Benzyl-3-(2-bromophenyl)propiononitrile, (I), was obtained in three steps (see scheme) through successive alkylation of methyl 2-cyanoacetate with benzyl chloride and potassium carbonate to give the intermediate ester (III), and then with 2-bromobenzyl bromide and potassium tert-butoxide to give (IV), followed by controlled hydrolysis and decarboxylation of the resulting cyano ester. By contrast, when potassium tert-butoxide was employed as the base in the first alkylation step, this gave a double alkylation leading directly to methyl 2-benzyl-2-cyano-3-phenylpropionate, (II). These two closely related nitriles (Figs. 1 and 2), each containing two benzyl substituents, have supramolecular structures that exhibit different types of hydrogen bonding leading to completely different patterns of supramolecular aggregation.
In (I) (Fig. 1), atom C2 is a stereogenic centre and the molecules are chiral. The compound is racemic, and the centrosymmetric space group P21/n accommodates equal numbers of the R and S enantiomers; the selected reference molecule has R configuration. In addition, the skeletal conformation does not exhibit even approximate symmetry, as shown by the leading torsion angles, particularly those around the C1—C17 and C2—C27 bonds (Table 1). By contrast, the conformation adopted by the molecule of (II) (Fig. 2), where there are no stereogenic centres, has approximate mirror symmetry (Table 3), but the modest deviations from exact symmetry are sufficient to render the molecules chiral. The chirality is a consequence only of the conformation in the solid state but, in the absence of inversion twinning, each crystal of (II) contains only a single enantiomer. In both compounds, the C1—C2 bonds are very long, as is characteristic of nitriles (Allen et al., 1987), with short C1—N1 bonds; the remaining bond lengths and angles present no unusual features.
The molecules of (I) are linked into simple chains by means of a single C—H⋯N hydrogen bond (Table 2). Aryl atom C13 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom N1 in the molecule at ( − x, + y, − z), so forming a C(8) (Bernstein et al., 1995) chain running parallel to the [010] direction and generated by the 21 screw axis along (, y, ) (Fig. 3). Two chains of this type, related to each other by inversion and hence antiparallel, pass through each unit cell, but there are no direction-specific interactions between adjacent chains.
The molecules of (II) are linked by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds (Table 4) into sheets, whose formation is readily analysed in terms of two simple one-dimensional substructures, each involving a single hydrogen bond. In one substructure, aryl atom C25 in the molecule at (x, y, z) acts as a hydrogen-bond donor to carbonyl atom O1 in the molecule at (−1 + x, y, z), so generating by translation a C(8) chain running parallel to the [100] direction (Fig. 4). In the second substructure, methylene atom C27 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H27A, to the C11–C16 aryl ring of the molecule at (2 − x, − + y, −z + ), so forming a chain running parallel to the [010] direction and generated by the 21 screw axis along (1, y, ) (Fig. 4). The combination of these [100] and [010] chains generates a sheet parallel to (001) (Fig. 4). Two such sheets, generated by the 21 screw axes at z = and z = , pass through each unit cell, but there are no direction-specific interactions between adjacent sheets. In neither of the structures of (I) and (II) are there any aromatic π–π stacking interactions.
| Figure 1 The R enantiomer of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. |
| Figure 2 A molecule of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. |
| Figure 3 Part of the crystal structure of (I), showing the formation of a C(8) chain along [010] built from C—H⋯N hydrogen bonds. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions ( − x, + y, − z) and ( − x, − + y, − z), respectively. |
| Figure 4 A stereoview of part of the crystal structure of (II), showing the formation of a sheet parallel to (001), formed by the combination of [100] and [010] chains. For the sake of clarity, H atoms not involved in the motifs shown have been omitted. |
Experimental
For the synthesis of (I), methyl 2-cyanoacetate (0.0128 mol) was added to a hot suspension (bath temperature 313 K) of potassium carbonate (0.048 mol) in tetrahydrofuran (50 ml) and the mixture was stirred for 30 min. Benzyl chloride (0.0245 mol) was then added and the reaction mixture was heated under reflux for 36 h. The mixture was cooled to ambient temperature, quenched by addition of brine and extracted with ethyl acetate (2 × 10 ml). The combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography (using 6% ethyl acetate in hexane as eluant) to afford methyl 2-cyano-3-phenylpropionate, (III), as a viscous yellow oil (yield 52%). A solution of ester (III) (2.64 mmol) in tetrahydrofuran (3 ml) was added dropwise under argon to a stirred suspension of potassium tert-butoxide (2.64 mmol) in anhydrous tetrahydrofuran (36 ml) at 393 K. After stirring for 10 min, 2-bromobenzyl bromide (2.64 mmol) in tetrahydrofuran (3 ml) was introduced slowly via syringe and the mixture was stirred for another 4 h at ambient temperature. The reaction was quenched by addition of brine and the mixture was then extracted with ethyl acetate (2 × 10 ml); the combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica (using 5% ethyl acetate in hexane as eluant) to give methyl 2-benzyl-3-(2-bromophenyl)-2-cyanopropionate, (IV), as a white powder (yield 68%, m.p. 365–366 K). A solution of ester (IV) (1.47 mmol) and water (14 × 10−3 ml) in dimethyl sulfoxide (2.0 ml) was added to a heated solution (375 K) of lithium chloride (2.94 mmol) in dry dimethyl sulfoxide (6.0 ml) under argon. This reaction mixture was heated at 405 K for 45 min. After cooling to ambient temperature, the reaction mixture was washed with brine (10 ml) and the organic layer was extracted with n-pentane (3 × 10 ml); the combined extracts were dried with magnesium sulfate and the solvent was removed under reduced pressure. The crude solid product was purified by flash chromatography on silica with 10% (v/v) ethyl acetate/hexane as eluant, affording a white powder, which was recrystallized from a solution of ethyl acetate/hexane to provide colourless crystals of (I) suitable for single-crystal X-ray diffraction (yield 48%, m.p. 351–352 K); MS (m/z, %): 301/299 (12:11, M+), 171/169 (18/17, [CH2C6H4Br]+), 91 (100, [C7H7]+). For the synthesis of (II), methyl cyanoacetate (1.055 g, 0.01 mol) was added dropwise to a suspension of potassium tert-butoxide (1.14 g, 0.01 mol) in anhydrous tetrahydrofuran (130 ml) at room temperature under an argon atmosphere. This mixture was stirred for 15 min, then benzyl chloride (1.287 g, 0.01 mol) was added slowly, followed by stirring for 4 h at ambient temperature. The reaction was then quenched by addition of brine (10 ml) and the mixture was extracted with ethyl acetate (2 × 10 ml); the combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography to afford (II) as a white powder; recrystallization from ethyl acetate gave colourless crystals suitable for single-crystal X-ray diffraction (yield 92%, m.p. 354–355 K); MS (m/z, %): 279 (7, M+), 188 (20), 156 (6), 91 (100, [C7H7]+).
Compound (I)
Crystal data
C16H14BrN Mr = 300.19 Monoclinic, P 21 /n a = 9.7924 (2) Å b = 14.8921 (2) Å c = 10.0937 (2) Å β = 113.392 (2)° V = 1350.98 (5) Å3 Z = 4 Dx = 1.476 Mg m−3 Mo Kα radiation μ = 3.02 mm−1 T = 120 (2) K Plate, colourless 0.20 × 0.15 × 0.08 mm
|
Data collection
Bruker–Nonius KappaCCD diffractometer φ and ω scans Absorption correction: multi-scan (SADABS; Sheldrick, 2003) Tmin = 0.583, Tmax = 0.794 26393 measured reflections 3077 independent reflections 2554 reflections with I > 2σ(I) Rint = 0.040 θmax = 27.5°
|
N1—C1 | 1.146 (2) | C1—C2 | 1.472 (2) | | C27—C2—C17—C11 | 170.00 (14) | C2—C17—C11—C12 | −81.6 (2) | C17—C2—C27—C21 | −74.01 (19) | C2—C27—C21—C22 | 99.62 (19) | | |
D—H⋯A | D—H | H⋯A | D⋯A | D—H⋯A | C13—H13⋯N1i | 0.95 | 2.58 | 3.294 (3) | 132 | Symmetry code: (i) . | |
Compound (II)
Crystal data
C18H17NO2 Mr = 279.33 Orthorhombic, P 21 21 21 a = 9.2000 (3) Å b = 9.3280 (2) Å c = 18.3031 (5) Å V = 1570.73 (7) Å3 Z = 4 Dx = 1.181 Mg m−3 Mo Kα radiation μ = 0.08 mm−1 T = 120 (2) K Block, colourless 0.70 × 0.45 × 0.32 mm
|
Data collection
Bruker–Nonius KappaCCD diffractometer φ and ω scans Absorption correction: multi-scan (SADABS; Sheldrick, 2003) Tmin = 0.938, Tmax = 0.976 13755 measured reflections 2053 independent reflections 1845 reflections with I > 2σ(I) Rint = 0.031 θmax = 27.5°
|
Refinement
Refinement on F2 R[F2 > 2σ(F2)] = 0.031 wR(F2) = 0.076 S = 1.14 2053 reflections 192 parameters H-atom parameters constrained w = 1/[σ2(Fo2) + (0.0366P)2 + 0.1369P] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max < 0.001 Δρmax = 0.17 e Å−3 Δρmin = −0.13 e Å−3 Extinction correction: SHELXL97 Extinction coefficient: 0.036 (4)
|
N1—C1 | 1.1428 (18) | C1—C2 | 1.4773 (19) | | C27—C2—C17—C11 | 174.44 (12) | C2—C17—C11—C12 | −92.52 (16) | C1—C2—C3—O2 | 6.48 (17) | C17—C2—C27—C21 | 175.07 (12) | C2—C27—C21—C22 | 77.05 (17) | C2—C3—O2—C4 | 176.60 (14) | | |
D—H⋯A | D—H | H⋯A | D⋯A | D—H⋯A | C25—H25⋯O1i | 0.95 | 2.53 | 3.467 (2) | 169 | C27—H27A⋯Cgii | 0.99 | 2.77 | 3.6799 (15) | 153 | Symmetry codes: (i) x-1, y, z; (ii) . | |
For compounds (I) and (II), the space groups P21/n and P212121, respectively, were uniquely assigned from the systematic absences. All H atoms were located in difference maps and then treated as riding atoms, with C—H distances of 0.95 (aromatic), 0.98 (CH3), 0.99 (CH2) or 1.00 Å (aliphatic CH), and with Uiso(H) = kUeq(C), where k = 1.5 for the methyl group and 1.2 for all other H atoms. In the absence of significant resonant scattering, the absolute configuration of the molecules of (II) in the crystal selected for data collection could not be established, but this configuration has no chemical significance; accordingly, the Friedel-equivalent reflections were merged prior to the final refinements.
For both compounds, data collection: COLLECT (Hooft, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: OSCAIL (McArdle, 2003) and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
Supporting information
For the synthesis of (I), methyl 2-cyanoacetate (0.0128 mol) was added to a hot suspension (bath temperature 313 K) of potassium carbonate (0.048 mol) in tetrahydrofuran (50 ml) and stirred for 30 min. Benzyl chloride (0.0245 mol) was then added and the reaction mixture was heated under reflux for 36 h. The mixture was cooled to ambient temperature, quenched by addition of brine and extracted with ethyl acetate (2 × 10 ml). The combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography (using 6% ethyl acetate in hexane as eluant) to afford methyl 2-cyano-3-phenylpropionate, (III), as a viscous yellow oil (yield 52%). A solution of ester (III) (2.64 mmol) in tetrahydrofuran (3 ml) was added dropwise under argon to a stirred suspension of potassium tert-butoxide (2.64 mmol) in anhydrous tetrahydrofuran (36 ml) at 393 K. After stirring for 10 min, 2-bromobenzylbromide (2.64 mmol) in tetrahydrofuran (3 ml) was introduced slowly via a syringe and the mixture was then stirred for another 4 h at ambient temperature. The reaction was quenched by addition of brine, and the mixture was then extracted with ethyl acetate (2 × 10 ml); the combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica (using 5% ethyl acetate in hexane as eluant) to give methyl-2-benzyl-3-(2-bromophenyl)-2-cyanopropionate, (IV), as a white powder (yield 68%, m.p. 365–366 K). A solution of ester (IV) (1.47 mmol) and water (14 × 10-3 ml) in dimethylsulfoxide (2.0 ml) was added to a heated solution (375 K) of lithium chloride (2.94 mmol) in dry dimethylsulfoxide (6.0 ml) under argon. This reaction mixture was heated at 405 K for 45 min. After cooling to ambient temperature, the reaction mixture was washed with brine (10 ml), and the organic layer was extracted with n-pentane (3 × 10 ml); the combined extracts were dried with magnesium sulfate and the solvent was removed under reduced pressure. The crude solid product was purified by flash chromatography on silica with 10% (v/v) ethyl acetate/hexane as eluant, affording a white powder, which was recrystallized from a solution of ethyl acetate/hexane to provide colourless crystals of (I) suitable for single-crystal X-ray diffraction (yield 48%, m.p. 351–352 K); MS (m/z, %) 301/299 (12:11, M+), 171/169 (18/17, [CH2C6H4Br]+), 91 (100, [C7H7]+). For the synthesis of (II), methyl cyanoacetate (1.055 g, 0.01 mol) was added dropwise to a suspension of potassium tert-butoxide (1.14 g, 0.01 mol) in anhydrous tetrahydrofuran (130 ml) at room temperature under an argon atmosphere. This mixture was stirred for 15 min, then benzyl chloride (1.287 g, 0.01 mol) was added slowly, followed by stirring for 4 h at ambient temperature. The reaction was then quenched by addition of brine (10 ml), which was followed by extraction with ethyl acetate (2 × 10 ml); the combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The residue was purified by flash chromatography to afford (II) as a white powder; recrystallization from ethyl acetate gave colourless crystals suitable for single-crystal X-ray diffraction (yield 92%, m.p. 354–355 K); MS (m/z, %) 279 (7, M+), 188 (20), 156 (6), 91 (100, [C7H7]+).
For compounds (I) and (II), the space groups P21/n and P212121, respectively, were uniquely assigned from the systematic absences. All H atoms were located in difference maps and then treated as riding atoms with C—H distances of 0.95 Å (aromatic), 0.98 Å (CH3), 0.99 Å (CH2) or 1.000 Å (aliphatic CH), and with Uiso(H) = kUeq(C), where k = 1.5 for the methyl group and 1.2 for all other H atoms. In the absence of significant resonant scattering, the absolute configuration of the molecules of (II) in the crystal selected for data collection could not be established, but this configuration has no chemical significance; accordingly, the Friedel-equivalent reflections were merged prior to the final refinements.
For both compounds, data collection: COLLECT (Hooft, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: OSCAIL (McArdle, 2003) and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
(I) 2-Benzyl-3-(2-bromophenyl)propiononitrile
top Crystal data top C16H14BrN | F(000) = 608 |
Mr = 300.19 | Dx = 1.476 Mg m−3 |
MonoclinicP21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 3077 reflections |
a = 9.7924 (2) Å | θ = 3.5–27.5° |
b = 14.8921 (2) Å | µ = 3.02 mm−1 |
c = 10.0937 (2) Å | T = 120 K |
β = 113.392 (2)° | Plate, colourless |
V = 1350.98 (5) Å3 | 0.20 × 0.15 × 0.08 mm |
Z = 4 | |
Data collection top Bruker–Nonius KappaCCD diffractometer | 3077 independent reflections |
Radiation source: Bruker-Nonius FR591 rotating anode | 2554 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.5° |
φ and ω scans | h = −12→11 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −19→19 |
Tmin = 0.583, Tmax = 0.794 | l = −13→13 |
26393 measured reflections | |
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)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.062 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0287P)2 + 0.3751P] where P = (Fo2 + 2Fc2)/3 |
3077 reflections | (Δ/σ)max = 0.001 |
163 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.57 e Å−3 |
Crystal data top C16H14BrN | V = 1350.98 (5) Å3 |
Mr = 300.19 | Z = 4 |
MonoclinicP21/n | Mo Kα radiation |
a = 9.7924 (2) Å | µ = 3.02 mm−1 |
b = 14.8921 (2) Å | T = 120 K |
c = 10.0937 (2) Å | 0.20 × 0.15 × 0.08 mm |
β = 113.392 (2)° | |
Data collection top Bruker–Nonius KappaCCD diffractometer | 3077 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2554 reflections with I > 2σ(I) |
Tmin = 0.583, Tmax = 0.794 | Rint = 0.040 |
26393 measured reflections | |
Refinement top R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.062 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.23 e Å−3 |
3077 reflections | Δρmin = −0.57 e Å−3 |
163 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.7527 (2) | 0.33787 (11) | 0.83201 (18) | 0.0379 (4) | |
C1 | 0.7252 (2) | 0.35260 (12) | 0.7127 (2) | 0.0287 (4) | |
C2 | 0.69086 (19) | 0.37339 (11) | 0.56021 (18) | 0.0250 (4) | |
C11 | 0.90007 (18) | 0.48676 (11) | 0.61769 (18) | 0.0235 (3) | |
C12 | 0.84884 (19) | 0.57099 (11) | 0.55921 (19) | 0.0248 (4) | |
Br12 | 0.68658 (2) | 0.581150 (12) | 0.37563 (2) | 0.03506 (8) | |
C13 | 0.9075 (2) | 0.65015 (12) | 0.6325 (2) | 0.0328 (4) | |
C14 | 1.0200 (2) | 0.64582 (14) | 0.7684 (2) | 0.0381 (5) | |
C15 | 1.0738 (2) | 0.56352 (14) | 0.8306 (2) | 0.0380 (5) | |
C16 | 1.0147 (2) | 0.48516 (13) | 0.7553 (2) | 0.0307 (4) | |
C17 | 0.83466 (19) | 0.40064 (11) | 0.54137 (19) | 0.0246 (4) | |
C27 | 0.6105 (2) | 0.29430 (12) | 0.4597 (2) | 0.0315 (4) | |
C21 | 0.53547 (19) | 0.32727 (11) | 0.30601 (19) | 0.0261 (4) | |
C22 | 0.5976 (2) | 0.31611 (12) | 0.2050 (2) | 0.0310 (4) | |
C23 | 0.5309 (2) | 0.35504 (13) | 0.0684 (2) | 0.0362 (5) | |
C24 | 0.4014 (2) | 0.40418 (13) | 0.0316 (2) | 0.0369 (4) | |
C25 | 0.3368 (2) | 0.41366 (14) | 0.1296 (2) | 0.0380 (5) | |
C26 | 0.4041 (2) | 0.37579 (13) | 0.2654 (2) | 0.0328 (4) | |
H2 | 0.6221 | 0.4262 | 0.5327 | 0.030* | |
H13 | 0.8704 | 0.7066 | 0.5895 | 0.039* | |
H14 | 1.0608 | 0.6996 | 0.8195 | 0.046* | |
H15 | 1.1509 | 0.5606 | 0.9245 | 0.046* | |
H16 | 1.0532 | 0.4289 | 0.7985 | 0.037* | |
H17A | 0.9091 | 0.3521 | 0.5793 | 0.030* | |
H17B | 0.8121 | 0.4075 | 0.4372 | 0.030* | |
H27A | 0.6835 | 0.2469 | 0.4654 | 0.038* | |
H27B | 0.5354 | 0.2682 | 0.4912 | 0.038* | |
H22 | 0.6860 | 0.2818 | 0.2290 | 0.037* | |
H23 | 0.5748 | 0.3477 | 0.0004 | 0.043* | |
H24 | 0.3572 | 0.4313 | −0.0610 | 0.044* | |
H25 | 0.2463 | 0.4461 | 0.1040 | 0.046* | |
H26 | 0.3592 | 0.3832 | 0.3326 | 0.039* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0507 (11) | 0.0329 (9) | 0.0306 (9) | −0.0101 (8) | 0.0168 (8) | −0.0009 (7) |
C1 | 0.0312 (10) | 0.0247 (8) | 0.0316 (10) | −0.0052 (7) | 0.0139 (8) | −0.0015 (7) |
C2 | 0.0281 (9) | 0.0232 (8) | 0.0239 (9) | −0.0026 (7) | 0.0106 (7) | 0.0004 (7) |
C11 | 0.0208 (9) | 0.0273 (8) | 0.0271 (9) | −0.0010 (7) | 0.0144 (7) | −0.0022 (7) |
C12 | 0.0241 (9) | 0.0274 (9) | 0.0292 (9) | 0.0012 (7) | 0.0172 (7) | 0.0013 (7) |
Br12 | 0.03919 (12) | 0.03753 (12) | 0.02985 (11) | 0.00873 (8) | 0.01518 (9) | 0.00909 (8) |
C13 | 0.0361 (11) | 0.0246 (9) | 0.0492 (12) | −0.0017 (8) | 0.0293 (10) | −0.0038 (8) |
C14 | 0.0346 (11) | 0.0372 (11) | 0.0520 (13) | −0.0121 (9) | 0.0271 (10) | −0.0194 (9) |
C15 | 0.0280 (10) | 0.0476 (12) | 0.0365 (11) | −0.0070 (9) | 0.0107 (9) | −0.0117 (9) |
C16 | 0.0242 (9) | 0.0337 (10) | 0.0326 (10) | 0.0006 (7) | 0.0096 (8) | −0.0016 (8) |
C17 | 0.0254 (9) | 0.0229 (8) | 0.0275 (9) | 0.0018 (7) | 0.0126 (7) | −0.0004 (7) |
C27 | 0.0364 (11) | 0.0259 (9) | 0.0319 (10) | −0.0075 (8) | 0.0133 (8) | −0.0014 (7) |
C21 | 0.0285 (9) | 0.0248 (8) | 0.0265 (9) | −0.0096 (7) | 0.0127 (8) | −0.0052 (7) |
C22 | 0.0317 (10) | 0.0282 (9) | 0.0384 (11) | −0.0058 (8) | 0.0193 (9) | −0.0098 (8) |
C23 | 0.0468 (12) | 0.0391 (10) | 0.0324 (10) | −0.0136 (9) | 0.0260 (10) | −0.0120 (8) |
C24 | 0.0414 (12) | 0.0402 (11) | 0.0265 (10) | −0.0089 (9) | 0.0109 (9) | −0.0029 (8) |
C25 | 0.0296 (11) | 0.0460 (12) | 0.0349 (11) | 0.0002 (9) | 0.0091 (9) | −0.0039 (9) |
C26 | 0.0280 (10) | 0.0444 (11) | 0.0293 (10) | −0.0062 (8) | 0.0149 (8) | −0.0071 (8) |
Geometric parameters (Å, º) top N1—C1 | 1.146 (2) | C17—H17A | 0.99 |
C1—C2 | 1.472 (2) | C17—H17B | 0.99 |
C2—C17 | 1.548 (2) | C27—C21 | 1.511 (3) |
C2—C27 | 1.550 (2) | C27—H27A | 0.99 |
C2—H2 | 1.00 | C27—H27B | 0.99 |
C11—C12 | 1.392 (2) | C21—C26 | 1.388 (3) |
C11—C16 | 1.397 (2) | C21—C22 | 1.390 (2) |
C11—C17 | 1.502 (2) | C22—C23 | 1.395 (3) |
C12—C13 | 1.389 (3) | C22—H22 | 0.95 |
C12—Br12 | 1.9088 (18) | C23—C24 | 1.381 (3) |
C13—C14 | 1.378 (3) | C23—H23 | 0.95 |
C13—H13 | 0.95 | C24—C25 | 1.377 (3) |
C14—C15 | 1.382 (3) | C24—H24 | 0.95 |
C14—H14 | 0.95 | C25—C26 | 1.384 (3) |
C15—C16 | 1.387 (3) | C25—H25 | 0.95 |
C15—H15 | 0.95 | C26—H26 | 0.95 |
C16—H16 | 0.95 | | |
| | | |
N1—C1—C2 | 178.84 (19) | C11—C17—H17B | 109.1 |
C1—C2—C17 | 110.02 (15) | C2—C17—H17B | 109.1 |
C1—C2—C27 | 111.74 (14) | H17A—C17—H17B | 107.8 |
C17—C2—C27 | 111.65 (14) | C21—C27—C2 | 109.80 (14) |
C1—C2—H2 | 107.7 | C21—C27—H27A | 109.7 |
C17—C2—H2 | 107.7 | C2—C27—H27A | 109.7 |
C27—C2—H2 | 107.7 | C21—C27—H27B | 109.7 |
C12—C11—C16 | 116.67 (16) | C2—C27—H27B | 109.7 |
C12—C11—C17 | 122.91 (16) | H27A—C27—H27B | 108.2 |
C16—C11—C17 | 120.40 (16) | C26—C21—C22 | 118.02 (17) |
C13—C12—C11 | 122.39 (17) | C26—C21—C27 | 119.26 (16) |
C13—C12—Br12 | 117.29 (14) | C22—C21—C27 | 122.59 (17) |
C11—C12—Br12 | 120.26 (13) | C21—C22—C23 | 120.36 (18) |
C14—C13—C12 | 119.24 (18) | C21—C22—H22 | 119.8 |
C14—C13—H13 | 120.4 | C23—C22—H22 | 119.8 |
C12—C13—H13 | 120.4 | C24—C23—C22 | 120.41 (17) |
C13—C14—C15 | 120.21 (18) | C24—C23—H23 | 119.8 |
C13—C14—H14 | 119.9 | C22—C23—H23 | 119.8 |
C15—C14—H14 | 119.9 | C25—C24—C23 | 119.71 (18) |
C14—C15—C16 | 119.76 (19) | C25—C24—H24 | 120.1 |
C14—C15—H15 | 120.1 | C23—C24—H24 | 120.1 |
C16—C15—H15 | 120.1 | C24—C25—C26 | 119.71 (19) |
C15—C16—C11 | 121.73 (18) | C24—C25—H25 | 120.1 |
C15—C16—H16 | 119.1 | C26—C25—H25 | 120.1 |
C11—C16—H16 | 119.1 | C25—C26—C21 | 121.76 (17) |
C11—C17—C2 | 112.60 (13) | C25—C26—H26 | 119.1 |
C11—C17—H17A | 109.1 | C21—C26—H26 | 119.1 |
C2—C17—H17A | 109.1 | | |
| | | |
C16—C11—C12—C13 | 0.0 (2) | C2—C17—C11—C12 | −81.6 (2) |
C17—C11—C12—C13 | 178.17 (15) | C1—C2—C27—C21 | 162.30 (15) |
C16—C11—C12—Br12 | −177.18 (12) | C17—C2—C27—C21 | −74.01 (19) |
C17—C11—C12—Br12 | 1.0 (2) | C2—C27—C21—C26 | −76.1 (2) |
C11—C12—C13—C14 | −0.3 (3) | C2—C27—C21—C22 | 99.62 (19) |
Br12—C12—C13—C14 | 176.96 (13) | C26—C21—C22—C23 | 1.7 (3) |
C12—C13—C14—C15 | 0.1 (3) | C27—C21—C22—C23 | −173.99 (16) |
C13—C14—C15—C16 | 0.4 (3) | C21—C22—C23—C24 | −0.8 (3) |
C14—C15—C16—C11 | −0.8 (3) | C22—C23—C24—C25 | −0.9 (3) |
C12—C11—C16—C15 | 0.5 (3) | C23—C24—C25—C26 | 1.6 (3) |
C17—C11—C16—C15 | −177.70 (16) | C24—C25—C26—C21 | −0.6 (3) |
C16—C11—C17—C2 | 96.49 (19) | C22—C21—C26—C25 | −1.1 (3) |
C1—C2—C17—C11 | −65.34 (18) | C27—C21—C26—C25 | 174.82 (17) |
C27—C2—C17—C11 | 170.00 (14) | | |
Hydrogen-bond geometry (Å, º) top D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···N1i | 0.95 | 2.58 | 3.294 (3) | 132 |
Symmetry code: (i) −x+3/2, y+1/2, −z+3/2. |
(II) Methyl 2-benzyl-2-cyano-3-phenylpropionate
top Crystal data top C18H17NO2 | F(000) = 592 |
Mr = 279.33 | Dx = 1.181 Mg m−3 |
OrthorhombicP212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 2053 reflections |
a = 9.2000 (3) Å | θ = 3.1–27.5° |
b = 9.3280 (2) Å | µ = 0.08 mm−1 |
c = 18.3031 (5) Å | T = 120 K |
V = 1570.73 (7) Å3 | Block, colourless |
Z = 4 | 0.70 × 0.45 × 0.32 mm |
Data collection top Bruker–Nonius KappaCCD diffractometer | 2053 independent reflections |
Radiation source: Bruker-Nonius FR591 rotating anode | 1845 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.031 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.1° |
φ and ω scans | h = −11→11 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −12→9 |
Tmin = 0.938, Tmax = 0.976 | l = −23→23 |
13755 measured reflections | |
Refinement top Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.031 | H-atom parameters constrained |
wR(F2) = 0.076 | w = 1/[σ2(Fo2) + (0.0366P)2 + 0.1369P] where P = (Fo2 + 2Fc2)/3 |
S = 1.14 | (Δ/σ)max < 0.001 |
2053 reflections | Δρmax = 0.17 e Å−3 |
192 parameters | Δρmin = −0.13 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.036 (4) |
Crystal data top C18H17NO2 | V = 1570.73 (7) Å3 |
Mr = 279.33 | Z = 4 |
OrthorhombicP212121 | Mo Kα radiation |
a = 9.2000 (3) Å | µ = 0.08 mm−1 |
b = 9.3280 (2) Å | T = 120 K |
c = 18.3031 (5) Å | 0.70 × 0.45 × 0.32 mm |
Data collection top Bruker–Nonius KappaCCD diffractometer | 2053 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1845 reflections with I > 2σ(I) |
Tmin = 0.938, Tmax = 0.976 | Rint = 0.031 |
13755 measured reflections | |
Refinement top R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.076 | H-atom parameters constrained |
S = 1.14 | Δρmax = 0.17 e Å−3 |
2053 reflections | Δρmin = −0.13 e Å−3 |
192 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.63881 (15) | 0.53190 (14) | 0.58573 (8) | 0.0341 (3) | |
C1 | 0.71766 (16) | 0.46636 (15) | 0.62054 (8) | 0.0243 (3) | |
C2 | 0.81637 (15) | 0.38743 (15) | 0.66989 (7) | 0.0224 (3) | |
C3 | 0.91664 (16) | 0.28559 (15) | 0.62827 (7) | 0.0232 (3) | |
O1 | 0.99765 (12) | 0.20544 (11) | 0.65954 (5) | 0.0307 (3) | |
O2 | 0.90626 (13) | 0.29829 (12) | 0.55649 (5) | 0.0344 (3) | |
C4 | 1.0061 (3) | 0.2090 (2) | 0.51535 (8) | 0.0555 (6) | |
C17 | 0.91542 (16) | 0.49774 (15) | 0.71047 (8) | 0.0263 (3) | |
C11 | 1.01740 (17) | 0.57554 (15) | 0.65934 (8) | 0.0268 (3) | |
C12 | 1.15696 (18) | 0.52370 (18) | 0.64673 (9) | 0.0345 (4) | |
C13 | 1.2484 (2) | 0.5898 (2) | 0.59672 (10) | 0.0457 (5) | |
C14 | 1.2012 (2) | 0.7079 (2) | 0.55842 (10) | 0.0490 (5) | |
C15 | 1.0648 (2) | 0.7621 (2) | 0.57103 (10) | 0.0474 (5) | |
C16 | 0.97331 (19) | 0.69705 (17) | 0.62138 (9) | 0.0356 (4) | |
C27 | 0.72551 (17) | 0.30095 (16) | 0.72641 (7) | 0.0265 (3) | |
C21 | 0.61703 (16) | 0.20030 (16) | 0.69218 (7) | 0.0259 (3) | |
C22 | 0.65887 (19) | 0.06998 (17) | 0.66174 (9) | 0.0352 (4) | |
C23 | 0.5590 (2) | −0.01746 (19) | 0.62686 (10) | 0.0446 (5) | |
C24 | 0.4144 (2) | 0.0237 (2) | 0.62290 (10) | 0.0450 (5) | |
C25 | 0.3702 (2) | 0.15048 (19) | 0.65444 (9) | 0.0398 (4) | |
C26 | 0.47069 (17) | 0.23822 (17) | 0.68895 (8) | 0.0306 (4) | |
H4A | 1.1063 | 0.2338 | 0.5284 | 0.083* | |
H4B | 0.9913 | 0.2248 | 0.4629 | 0.083* | |
H4C | 0.9881 | 0.1079 | 0.5269 | 0.083* | |
H17A | 0.8533 | 0.5688 | 0.7358 | 0.032* | |
H17B | 0.9732 | 0.4468 | 0.7480 | 0.032* | |
H12 | 1.1901 | 0.4419 | 0.6727 | 0.041* | |
H13 | 1.3436 | 0.5534 | 0.5889 | 0.055* | |
H14 | 1.2629 | 0.7518 | 0.5233 | 0.059* | |
H15 | 1.0329 | 0.8445 | 0.5451 | 0.057* | |
H16 | 0.8795 | 0.7360 | 0.6300 | 0.043* | |
H27A | 0.7926 | 0.2448 | 0.7575 | 0.032* | |
H27B | 0.6730 | 0.3691 | 0.7584 | 0.032* | |
H22 | 0.7575 | 0.0405 | 0.6649 | 0.042* | |
H23 | 0.5895 | −0.1054 | 0.6057 | 0.054* | |
H24 | 0.3459 | −0.0355 | 0.5985 | 0.054* | |
H25 | 0.2708 | 0.1779 | 0.6525 | 0.048* | |
H26 | 0.4393 | 0.3254 | 0.7107 | 0.037* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0291 (7) | 0.0330 (7) | 0.0403 (7) | −0.0020 (6) | −0.0082 (6) | 0.0052 (6) |
C1 | 0.0222 (7) | 0.0241 (7) | 0.0266 (7) | −0.0037 (6) | −0.0025 (6) | −0.0007 (6) |
C2 | 0.0209 (7) | 0.0255 (7) | 0.0209 (6) | 0.0001 (6) | −0.0042 (5) | 0.0002 (5) |
C3 | 0.0236 (7) | 0.0234 (7) | 0.0226 (6) | −0.0045 (6) | −0.0026 (5) | 0.0016 (6) |
O1 | 0.0281 (6) | 0.0356 (6) | 0.0283 (5) | 0.0065 (5) | −0.0007 (5) | 0.0059 (5) |
O2 | 0.0470 (7) | 0.0366 (6) | 0.0194 (5) | 0.0139 (6) | −0.0019 (5) | −0.0012 (5) |
C4 | 0.0804 (15) | 0.0610 (12) | 0.0252 (8) | 0.0356 (13) | 0.0064 (9) | −0.0030 (8) |
C17 | 0.0239 (7) | 0.0315 (8) | 0.0234 (7) | −0.0019 (6) | −0.0038 (6) | −0.0050 (6) |
C11 | 0.0261 (7) | 0.0269 (7) | 0.0274 (7) | −0.0067 (6) | −0.0040 (6) | −0.0064 (6) |
C12 | 0.0277 (8) | 0.0318 (8) | 0.0439 (9) | −0.0051 (7) | −0.0007 (7) | −0.0096 (7) |
C13 | 0.0341 (9) | 0.0471 (11) | 0.0558 (10) | −0.0130 (9) | 0.0122 (9) | −0.0231 (9) |
C14 | 0.0534 (12) | 0.0518 (11) | 0.0419 (9) | −0.0267 (10) | 0.0118 (8) | −0.0094 (9) |
C15 | 0.0568 (12) | 0.0397 (10) | 0.0457 (10) | −0.0190 (9) | −0.0076 (9) | 0.0075 (8) |
C16 | 0.0318 (9) | 0.0306 (8) | 0.0444 (9) | −0.0068 (7) | −0.0067 (7) | −0.0006 (7) |
C27 | 0.0258 (8) | 0.0322 (8) | 0.0215 (6) | −0.0006 (7) | −0.0010 (6) | 0.0019 (6) |
C21 | 0.0261 (7) | 0.0299 (7) | 0.0216 (6) | −0.0045 (6) | 0.0011 (6) | 0.0055 (6) |
C22 | 0.0341 (9) | 0.0328 (8) | 0.0386 (8) | −0.0023 (7) | 0.0044 (8) | 0.0009 (7) |
C23 | 0.0536 (12) | 0.0360 (9) | 0.0442 (9) | −0.0153 (9) | 0.0086 (9) | −0.0052 (8) |
C24 | 0.0460 (11) | 0.0481 (10) | 0.0409 (9) | −0.0261 (9) | −0.0012 (8) | 0.0028 (8) |
C25 | 0.0280 (8) | 0.0509 (10) | 0.0405 (9) | −0.0137 (8) | −0.0001 (8) | 0.0110 (8) |
C26 | 0.0265 (8) | 0.0357 (8) | 0.0295 (7) | −0.0022 (6) | 0.0043 (6) | 0.0055 (7) |
Geometric parameters (Å, º) top N1—C1 | 1.1428 (18) | C14—C15 | 1.372 (3) |
C1—C2 | 1.4773 (19) | C14—H14 | 0.95 |
C2—C3 | 1.5277 (19) | C15—C16 | 1.388 (2) |
C2—C27 | 1.5555 (19) | C15—H15 | 0.95 |
C2—C17 | 1.5622 (19) | C16—H16 | 0.95 |
C3—O1 | 1.2009 (17) | C27—C21 | 1.507 (2) |
C3—O2 | 1.3225 (17) | C27—H27A | 0.99 |
O2—C4 | 1.451 (2) | C27—H27B | 0.99 |
C4—H4A | 0.98 | C21—C22 | 1.391 (2) |
C4—H4B | 0.98 | C21—C26 | 1.393 (2) |
C4—H4C | 0.98 | C22—C23 | 1.385 (2) |
C17—C11 | 1.511 (2) | C22—H22 | 0.95 |
C17—H17A | 0.99 | C23—C24 | 1.386 (3) |
C17—H17B | 0.99 | C23—H23 | 0.95 |
C11—C16 | 1.390 (2) | C24—C25 | 1.377 (3) |
C11—C12 | 1.391 (2) | C24—H24 | 0.95 |
C12—C13 | 1.388 (2) | C25—C26 | 1.387 (2) |
C12—H12 | 0.95 | C25—H25 | 0.95 |
C13—C14 | 1.376 (3) | C26—H26 | 0.95 |
C13—H13 | 0.95 | | |
| | | |
N1—C1—C2 | 176.10 (15) | C15—C14—H14 | 120.1 |
C1—C2—C3 | 112.10 (11) | C13—C14—H14 | 120.1 |
C1—C2—C27 | 109.55 (11) | C14—C15—C16 | 120.36 (18) |
C3—C2—C27 | 109.49 (11) | C14—C15—H15 | 119.8 |
C1—C2—C17 | 108.72 (11) | C16—C15—H15 | 119.8 |
C3—C2—C17 | 107.12 (11) | C15—C16—C11 | 120.75 (17) |
C27—C2—C17 | 109.81 (11) | C15—C16—H16 | 119.6 |
O1—C3—O2 | 125.04 (13) | C11—C16—H16 | 119.6 |
O1—C3—C2 | 121.61 (12) | C21—C27—C2 | 113.75 (11) |
O2—C3—C2 | 113.33 (12) | C21—C27—H27A | 108.8 |
C3—O2—C4 | 114.73 (12) | C2—C27—H27A | 108.8 |
O2—C4—H4A | 109.5 | C21—C27—H27B | 108.8 |
O2—C4—H4B | 109.5 | C2—C27—H27B | 108.8 |
H4A—C4—H4B | 109.5 | H27A—C27—H27B | 107.7 |
O2—C4—H4C | 109.5 | C22—C21—C26 | 118.17 (15) |
H4A—C4—H4C | 109.5 | C22—C21—C27 | 121.84 (14) |
H4B—C4—H4C | 109.5 | C26—C21—C27 | 119.97 (14) |
C11—C17—C2 | 112.59 (11) | C23—C22—C21 | 121.05 (16) |
C11—C17—H17A | 109.1 | C23—C22—H22 | 119.5 |
C2—C17—H17A | 109.1 | C21—C22—H22 | 119.5 |
C11—C17—H17B | 109.1 | C22—C23—C24 | 119.85 (17) |
C2—C17—H17B | 109.1 | C22—C23—H23 | 120.1 |
H17A—C17—H17B | 107.8 | C24—C23—H23 | 120.1 |
C16—C11—C12 | 118.02 (15) | C25—C24—C23 | 119.93 (17) |
C16—C11—C17 | 121.34 (14) | C25—C24—H24 | 120.0 |
C12—C11—C17 | 120.59 (14) | C23—C24—H24 | 120.0 |
C13—C12—C11 | 120.98 (16) | C24—C25—C26 | 120.07 (18) |
C13—C12—H12 | 119.5 | C24—C25—H25 | 120.0 |
C11—C12—H12 | 119.5 | C26—C25—H25 | 120.0 |
C14—C13—C12 | 120.00 (18) | C25—C26—C21 | 120.90 (16) |
C14—C13—H13 | 120.0 | C25—C26—H26 | 119.6 |
C12—C13—H13 | 120.0 | C21—C26—H26 | 119.6 |
C15—C14—C13 | 119.86 (17) | | |
| | | |
C1—C2—C3—O1 | −174.96 (13) | C14—C15—C16—C11 | −0.6 (3) |
C27—C2—C3—O1 | −53.17 (17) | C12—C11—C16—C15 | 1.7 (2) |
C17—C2—C3—O1 | 65.86 (16) | C17—C11—C16—C15 | −175.78 (15) |
C27—C2—C3—O2 | 128.27 (13) | C1—C2—C27—C21 | 55.74 (15) |
C17—C2—C3—O2 | −112.71 (13) | C3—C2—C27—C21 | −67.58 (15) |
O1—C3—O2—C4 | −1.9 (2) | C17—C2—C27—C21 | 175.07 (12) |
C1—C2—C17—C11 | −65.72 (15) | C2—C27—C21—C22 | 77.05 (17) |
C3—C2—C17—C11 | 55.62 (15) | C2—C3—O2—C4 | 176.60 (14) |
C27—C2—C17—C11 | 174.44 (12) | C2—C27—C21—C26 | −101.50 (16) |
C2—C17—C11—C16 | 84.86 (16) | C26—C21—C22—C23 | 2.3 (2) |
C2—C17—C11—C12 | −92.52 (16) | C27—C21—C22—C23 | −176.31 (14) |
C1—C2—C3—O2 | 6.48 (17) | C21—C22—C23—C24 | −1.0 (3) |
C16—C11—C12—C13 | −1.2 (2) | C22—C23—C24—C25 | −0.8 (3) |
C17—C11—C12—C13 | 176.28 (14) | C23—C24—C25—C26 | 1.2 (3) |
C11—C12—C13—C14 | −0.4 (2) | C24—C25—C26—C21 | 0.2 (2) |
C12—C13—C14—C15 | 1.5 (3) | C22—C21—C26—C25 | −1.9 (2) |
C13—C14—C15—C16 | −1.0 (3) | C27—C21—C26—C25 | 176.73 (13) |
Hydrogen-bond geometry (Å, º) top D—H···A | D—H | H···A | D···A | D—H···A |
C25—H25···O1i | 0.95 | 2.53 | 3.467 (2) | 169 |
C27—H27A···Cgii | 0.99 | 2.77 | 3.6799 (15) | 153 |
Symmetry codes: (i) x−1, y, z; (ii) −x+2, y−1/2, −z+3/2. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C16H14BrN | C18H17NO2 |
Mr | 300.19 | 279.33 |
Crystal system, space group | MonoclinicP21/n | OrthorhombicP212121 |
Temperature (K) | 120 | 120 |
a, b, c (Å) | 9.7924 (2), 14.8921 (2), 10.0937 (2) | 9.2000 (3), 9.3280 (2), 18.3031 (5) |
α, β, γ (°) | 90, 113.392 (2), 90 | 90, 90, 90 |
V (Å3) | 1350.98 (5) | 1570.73 (7) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 3.02 | 0.08 |
Crystal size (mm) | 0.20 × 0.15 × 0.08 | 0.70 × 0.45 × 0.32 |
|
Data collection |
Diffractometer | Bruker–Nonius KappaCCD diffractometer | Bruker–Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.583, 0.794 | 0.938, 0.976 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 26393, 3077, 2554 | 13755, 2053, 1845 |
Rint | 0.040 | 0.031 |
(sin θ/λ)max (Å−1) | 0.649 | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.062, 1.07 | 0.031, 0.076, 1.14 |
No. of reflections | 3077 | 2053 |
No. of parameters | 163 | 192 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.23, −0.57 | 0.17, −0.13 |
Selected geometric parameters (Å, º) for (I) topN1—C1 | 1.146 (2) | C1—C2 | 1.472 (2) |
| | | |
C27—C2—C17—C11 | 170.00 (14) | C17—C2—C27—C21 | −74.01 (19) |
C2—C17—C11—C12 | −81.6 (2) | C2—C27—C21—C22 | 99.62 (19) |
Hydrogen-bond geometry (Å, º) for (I) top D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···N1i | 0.95 | 2.58 | 3.294 (3) | 132 |
Symmetry code: (i) −x+3/2, y+1/2, −z+3/2. |
Selected geometric parameters (Å, º) for (II) topN1—C1 | 1.1428 (18) | C1—C2 | 1.4773 (19) |
| | | |
C27—C2—C17—C11 | 174.44 (12) | C17—C2—C27—C21 | 175.07 (12) |
C2—C17—C11—C12 | −92.52 (16) | C2—C27—C21—C22 | 77.05 (17) |
C1—C2—C3—O2 | 6.48 (17) | C2—C3—O2—C4 | 176.60 (14) |
Hydrogen-bond geometry (Å, º) for (II) top D—H···A | D—H | H···A | D···A | D—H···A |
C25—H25···O1i | 0.95 | 2.53 | 3.467 (2) | 169 |
C27—H27A···Cgii | 0.99 | 2.77 | 3.6799 (15) | 153 |
Symmetry codes: (i) x−1, y, z; (ii) −x+2, y−1/2, −z+3/2. |
Acknowledgements
X-ray data were collected at the EPSRC National Crystallography Service, University of Southampton, England. The authors thank the staff for all their help and advice. JC and JMT thank the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía, Spain) and the Universidad de Jaén for financial support; JMT also thanks the Universidad de Jaén for a scholarship grant supporting a short stay at the EPSRC National Crystallography Service. GC and LMJG thank COLCIENCIAS, UNIVALLE (Universidad del Valle, Colombia), for financial support.
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| STRUCTURAL CHEMISTRY |
ISSN: 2053-2296
The synthesis of heterocyclic systems containing pyrollidine fragments is an important goal because of the widespread occurrence of such systems both in biologically active natural products and in therapeutic agents. We present here the molecular and supramolecular structures of two compounds prepared for use as intermediates in the synthesis of pyrollidines using radical cyclization methodology. 2-Benzyl-3-(2-bromophenyl)propiononitrile, (I), was obtained in three steps (see scheme) through successive alkylation of methyl 2-cyanoacetate with benzyl chloride and potassium carbonate to give the intermediate ester (III), and then with 2-bromobenzyl bromide and potassium tert-butoxide to give (IV), followed by controlled hydrolysis and decarboxylation of the resulting cyano ester. By contrast, when potassium tert-butoxide was employed as the base in the first alkylation step, this gave a double alkylation leading directly to methyl 2-benzyl-2-cyano-3-phenylpropionate, (II). These two closely related nitriles (I) and (II) (Figs. 1 and 2), each containing two benzyl substituents, have supramolecular structures that exhibit different types of hydrogen bonding leading to completely different patterns of supramolecular aggregation.
In (I) (Fig. 1), atom C2 is a stereogenic centre and the molecules are chiral. The compound is racemic, and the centrosymmetric space group P21/n accommodates equal numbers of the (R) and (S) enantiomers: the selected reference molecule has (R) configuration. In addition, the skeletal conformation does not exhibit even approximate symmetry, as shown by the leading torsion angles, particularly those around the bonds C1—C17 and C2—C27 (Table 1). By contrast, the conformation adopted by the molecule of (II) (Fig. 2), where there are no stereogenic centres, has approximate mirror symmetry (Table 3), but the modest deviations from exact symmetry are sufficient to render the molecules chiral. The chirality is a consequence only of the conformation in the solid state but, in the absence of inversion twinning, each crystal of (II) contains only a single enantiomer. In both compounds, the C1—C2 bonds are very long, as is characteristic of nitriles (Allen et al., 1987), with short C1—N1 bonds; the remaining bond lengths and angles present no unusual features.
The molecules of (I) are linked into simple chains by means of a single C—H····N hydrogen bond (Table 2). Aryl atom C13 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom N1 in the molecule at (3/2 - x, 1/2 + y, 3/2 - z), so forming a C(8) (Bernstein et al., 1995) chain running parallel to the [010] direction and generated by the 21 screw axis along (3/4, y, 3/4) (Fig. 3). Two chains of this type, related to each other by inversion and hence antiparallel, pass through each unit cell, but there are no direction-specific interactions between adjacent chains.
The molecules of (II) are linked by a combination of C—H···O and C—H···π(arene) hydrogen bonds (Table 4) into sheets, whose formation is readily analysed in terms of two simple one-dimensional sub-structures, each involving a single hydrogen bond. In one sub-structure, aryl atom C25 in the molecule at (x, y, z) acts as a hydrogen-bond donor to carbonyl atom O1 in the molecule at (-1 + x, y, z), so generating by translation a C(8) chain running parallel to the [100] direction (Fig. 4). In the second sub-structure, methylene atom C27 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H27A, to the aryl ring C11–C16 of the molecule at (2 - x, -1/2 + y, 3/4 - z) [-z + 3/2 in Table 4?], so forming a chain running parallel to the [010] direction and generated by the 21 screw axis along (1, y, 3/4) (Fig. 4). The combination of these [100] and [010] chains generates a sheet parallel to (001) (Fig. 4). Two such sheets, generated by the 21 screw axes at z = 1/4 and z = 3/4, pass through each unit cell, but there are no direction-specific interactions between adjacent sheets. In neither of the structures of (I) and (II) are there any aromatic π–π stacking interactions.