organic compounds
(5R*)-5-[(2S*,5S*)-1-Methoxy-5-phenylpyrrolidin-2-yl]-3-methylfuran-2(5H)-one
aSchool of Medicine, Keio University, Hiyoshi 4-1-1, Kohoku-ku, Yokohama 223-8521, Japan, and bDepartment of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan
*Correspondence e-mail: oec@a6.keio.jp
In the title compound, C16H19NO3, the pyrrolidine ring is in a twist conformation. The dihedral angle between the dihydrofuran ring [maximum deviation = 0.0016 (11) Å] and the phenyl ring is 47.22 (8)°. In the crystal, molecules are linked by weak C—H⋯O hydrogen bonds, forming helical chains along the b-axis direction. The chains are further linked by C—H⋯π interactions to constitute a three-dimensional architecture.
Keywords: crystal structure.
CCDC reference: 1010196
Related literature
For noteworthy mild reactions of N-alkoxyamines, see: Hawker et al. (2001). For the reaction of Weinreb amide, see: Nahm & Weinreb (1981). For the synthesis of the title compound, see: Yoritate et al. (2014). For a related article utilizing similar compounds, see: Yanagita et al. (2013). For details of ring conformations, see: Cremer & Pople (1975).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2012); cell SAINT (Bruker, 2012); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010) and PLATON (Spek, 2009).
Supporting information
CCDC reference: 1010196
10.1107/S1600536814014974/is5367sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814014974/is5367Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814014974/is5367Isup3.cml
The title compound was synthesized from 4-oxo-4-phenylbutyric acid (Yoritate et al., 2014), and recrystallized from a toluene solution by slow evaporation at ambient temperature; M.p. 358.5–359.9 K (not corrected). 1H NMR (500 MHz, CDCl3) δ (p.p.m.) = 7.41–7.37 (m, 2H, Ph), 7.36–7.31 (m, 2H, Ph), 7.29–7.24 (m, 1H, Ph), 7.13 (qd, J = 1.7, 1.7 Hz, 1H, H4), 5.35–5.31 (m, 1H, H5), 4.33 (dd, J = 8.2, 7.5 Hz, 1H, H12), 3.56 (ddd, J = 8.3, 4.9, 4.9 Hz, 1H, H9), 3.35 (s, 3H, OMe), 2.20 (dddd, J = 12.9, 10.0, 7.5, 4.0 Hz, 1H, H11A), 2.00 (dddd, J = 13.1, 10.3, 8.3, 4.0 Hz, 1H, H10A), 1.95 (dd, J = 1.7, 1.7 Hz, 3H, CMe), 1.93–1.84 (m, 1H, H11B), 1.62 (dddd, J = 13.1, 10.0, 6.6, 4.9 Hz, 1H, H10B); 13C NMR (125 MHz, CDCl3) δ (p.p.m.) = 174.6 (C), 148.1 (CH), 141.1 (C), 130.7 (C), 128.3 (CH), 128.1 (CH), 127.4 (CH), 80.5 (CH), 68.6 (CH), 65.3 (CH), 61.2 (CH2), 28.9 (CH2), 22.6 (CH2), 10.9 (CH3); Anal. calcd. for C16H19NO3: C 70.31, H 7.01, N 5.12%, found: C 70.15, H 7.00, N 5.06%.
C-bound H atoms were positioned geometrically with C—H = 0.95–1.00 Å, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C). The Friedel opposites were merged before the final
because no significant was observed and the was a meaningless value of –1.2 (10) with 1054 Bijvoet pairs. One reflection (7 3 4) has been omitted in the final refinement.Data collection: APEX2 (Bruker, 2012); cell
SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010) and PLATON (Spek, 2009).Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms. | |
Fig. 2. The crystal packing of the title compound, viewed down the a axis. Dashed lines indicate the intermolecular C5—H···O6 interactions, making helical chains along [010]. Only H atoms involved in hydrogen bonds were shown for clarity. Symmetry codes: (i) –x + 1, y + 1/2, –z + 3/2; (iv) x – 1/2, –y + 1/2, –z + 1; (v) –x + 1/2, –y + 1, z – 1/2; (vi) x – 1/2, –y + 3/2, –z + 1; (vii) –x + 1, y – 1/2, –z + 3/2. | |
Fig. 3. A view for the intermolecular C—H···π interactions (dashed lines), showing parallel (C10—H10A···Cg1) and alternated (C16—H16···Cg3) chains along [100]. Cg1 and Cg3 are the centroids of the O1/C2–C5 dihydrofuran and the C15–C20 phenyl rings, respectively. Only H atoms involved in hydrogen bonds were shown for clarity. Symmetry codes: (ii) x – 1, y, z; (iii) x + 1/2, –y + 1/2, –z + 1; (iv) x – 1/2, –y + 1/2, –z + 1; (viii) x + 1, y, z. | |
Fig. 4. Molecular conformation indicating intramolecular C—H···O and C—H···π interactions with dashed lines. Cg1 is a centroid of the O1/C2–C5 dihydrofuran ring. |
C16H19NO3 | Dx = 1.292 Mg m−3 |
Mr = 273.32 | Melting point: 358.5 K |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.5427 (3) Å | Cell parameters from 9968 reflections |
b = 10.8219 (5) Å | θ = 2.8–25.4° |
c = 19.8397 (10) Å | µ = 0.09 mm−1 |
V = 1404.74 (12) Å3 | T = 90 K |
Z = 4 | Prism, colourless |
F(000) = 584 | 0.54 × 0.51 × 0.40 mm |
Bruker D8 diffractometer | 1510 independent reflections |
Radiation source: fine-focus sealed tube | 1474 reflections with I > 2σ(I) |
Multilayered confocal mirror monochromator | Rint = 0.027 |
Detector resolution: 8.333 pixels mm-1 | θmax = 25.4°, θmin = 2.8° |
ω scans | h = −7→7 |
Absorption correction: multi-scan (SADABS; Bruker, 2012) | k = −13→11 |
Tmin = 0.95, Tmax = 0.97 | l = −23→22 |
12710 measured reflections |
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) = 0.075 | w = 1/[σ2(Fo2) + (0.0428P)2 + 0.402P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.014 |
1510 reflections | Δρmax = 0.21 e Å−3 |
184 parameters | Δρmin = −0.17 e Å−3 |
0 restraints | Extinction correction: SHELXL |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.029 (3) |
C16H19NO3 | V = 1404.74 (12) Å3 |
Mr = 273.32 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 6.5427 (3) Å | µ = 0.09 mm−1 |
b = 10.8219 (5) Å | T = 90 K |
c = 19.8397 (10) Å | 0.54 × 0.51 × 0.40 mm |
Bruker D8 diffractometer | 1510 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2012) | 1474 reflections with I > 2σ(I) |
Tmin = 0.95, Tmax = 0.97 | Rint = 0.027 |
12710 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.075 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.21 e Å−3 |
1510 reflections | Δρmin = −0.17 e Å−3 |
184 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.28934 (19) | 0.36404 (11) | 0.70066 (5) | 0.0197 (3) | |
C2 | 0.3603 (3) | 0.29777 (16) | 0.75407 (8) | 0.0200 (4) | |
C3 | 0.3704 (3) | 0.37890 (16) | 0.81354 (8) | 0.0198 (4) | |
C4 | 0.3059 (3) | 0.48928 (16) | 0.79475 (8) | 0.0198 (4) | |
H4 | 0.2965 | 0.559 | 0.8237 | 0.024* | |
C5 | 0.2496 (3) | 0.48950 (17) | 0.72169 (8) | 0.0181 (4) | |
H5 | 0.3424 | 0.5469 | 0.6967 | 0.022* | |
O6 | 0.4060 (2) | 0.19033 (12) | 0.74867 (6) | 0.0268 (3) | |
C7 | 0.4522 (3) | 0.33239 (18) | 0.87893 (8) | 0.0272 (4) | |
H7A | 0.4346 | 0.3959 | 0.9137 | 0.041* | |
H7B | 0.5978 | 0.3132 | 0.874 | 0.041* | |
H7C | 0.3779 | 0.2576 | 0.8921 | 0.041* | |
N8 | −0.0284 (2) | 0.53897 (13) | 0.63598 (7) | 0.0185 (3) | |
C9 | 0.0267 (3) | 0.52517 (16) | 0.70776 (8) | 0.0179 (4) | |
H9 | −0.0038 | 0.6045 | 0.7316 | 0.021* | |
C10 | −0.1287 (3) | 0.42769 (16) | 0.73027 (8) | 0.0209 (4) | |
H10A | −0.2569 | 0.4672 | 0.7457 | 0.025* | |
H10B | −0.0728 | 0.3768 | 0.7674 | 0.025* | |
C11 | −0.1671 (3) | 0.34798 (17) | 0.66697 (8) | 0.0245 (4) | |
H11A | −0.1119 | 0.2636 | 0.6735 | 0.029* | |
H11B | −0.3154 | 0.3418 | 0.6576 | 0.029* | |
C12 | −0.0570 (3) | 0.41297 (15) | 0.60873 (8) | 0.0193 (4) | |
H12 | 0.0794 | 0.3736 | 0.6014 | 0.023* | |
O13 | 0.13547 (19) | 0.59737 (11) | 0.59960 (6) | 0.0208 (3) | |
C14 | 0.0574 (3) | 0.70653 (17) | 0.56898 (9) | 0.0251 (4) | |
H14A | −0.0573 | 0.6851 | 0.5394 | 0.038* | |
H14B | 0.1653 | 0.7461 | 0.5424 | 0.038* | |
H14C | 0.0103 | 0.7636 | 0.604 | 0.038* | |
C15 | −0.1725 (3) | 0.41689 (16) | 0.54286 (8) | 0.0205 (4) | |
C16 | −0.0888 (3) | 0.36521 (18) | 0.48516 (8) | 0.0258 (4) | |
H16 | 0.0411 | 0.3262 | 0.4873 | 0.031* | |
C17 | −0.1934 (4) | 0.36997 (19) | 0.42435 (9) | 0.0358 (5) | |
H17 | −0.1347 | 0.3345 | 0.385 | 0.043* | |
C18 | −0.3824 (4) | 0.42609 (19) | 0.42089 (10) | 0.0398 (6) | |
H18 | −0.4529 | 0.4303 | 0.3791 | 0.048* | |
C19 | −0.4695 (4) | 0.47615 (19) | 0.47816 (11) | 0.0370 (5) | |
H19 | −0.6006 | 0.5136 | 0.4758 | 0.044* | |
C20 | −0.3655 (3) | 0.47190 (18) | 0.53920 (10) | 0.0276 (4) | |
H20 | −0.4257 | 0.5064 | 0.5785 | 0.033* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0201 (6) | 0.0197 (6) | 0.0194 (5) | 0.0030 (5) | −0.0008 (5) | −0.0022 (5) |
C2 | 0.0136 (8) | 0.0222 (9) | 0.0241 (8) | 0.0007 (7) | 0.0023 (7) | 0.0019 (7) |
C3 | 0.0147 (8) | 0.0230 (8) | 0.0218 (8) | −0.0029 (8) | 0.0017 (7) | 0.0009 (7) |
C4 | 0.0176 (9) | 0.0211 (8) | 0.0208 (8) | −0.0024 (8) | 0.0002 (7) | −0.0018 (7) |
C5 | 0.0195 (9) | 0.0159 (8) | 0.0188 (8) | −0.0004 (7) | 0.0000 (7) | 0.0002 (6) |
O6 | 0.0274 (7) | 0.0209 (6) | 0.0321 (6) | 0.0070 (6) | −0.0013 (6) | −0.0006 (5) |
C7 | 0.0262 (10) | 0.0310 (10) | 0.0243 (8) | 0.0009 (9) | −0.0032 (8) | 0.0054 (8) |
N8 | 0.0179 (7) | 0.0181 (7) | 0.0194 (7) | −0.0025 (6) | 0.0022 (6) | 0.0024 (6) |
C9 | 0.0182 (9) | 0.0168 (8) | 0.0187 (8) | 0.0017 (7) | 0.0014 (7) | 0.0000 (7) |
C10 | 0.0175 (8) | 0.0214 (9) | 0.0237 (8) | −0.0005 (8) | 0.0027 (7) | 0.0025 (7) |
C11 | 0.0253 (10) | 0.0231 (9) | 0.0251 (8) | −0.0063 (8) | −0.0019 (8) | 0.0039 (7) |
C12 | 0.0198 (9) | 0.0159 (8) | 0.0223 (8) | 0.0000 (7) | −0.0003 (7) | 0.0002 (7) |
O13 | 0.0178 (6) | 0.0212 (6) | 0.0235 (6) | −0.0030 (5) | 0.0019 (5) | 0.0052 (5) |
C14 | 0.0280 (10) | 0.0247 (9) | 0.0227 (8) | −0.0052 (8) | −0.0044 (8) | 0.0078 (7) |
C15 | 0.0238 (9) | 0.0151 (8) | 0.0226 (8) | −0.0051 (8) | −0.0028 (7) | 0.0015 (6) |
C16 | 0.0297 (10) | 0.0222 (9) | 0.0254 (8) | −0.0071 (9) | 0.0004 (8) | 0.0003 (7) |
C17 | 0.0543 (14) | 0.0300 (10) | 0.0231 (8) | −0.0180 (12) | −0.0020 (9) | 0.0010 (8) |
C18 | 0.0557 (15) | 0.0305 (11) | 0.0330 (10) | −0.0178 (11) | −0.0238 (11) | 0.0103 (9) |
C19 | 0.0349 (12) | 0.0220 (10) | 0.0541 (13) | −0.0045 (9) | −0.0221 (11) | 0.0069 (9) |
C20 | 0.0268 (10) | 0.0198 (9) | 0.0362 (10) | −0.0017 (9) | −0.0062 (9) | −0.0002 (8) |
O1—C2 | 1.361 (2) | C11—C12 | 1.532 (2) |
O1—C5 | 1.444 (2) | C11—H11A | 0.99 |
C2—O6 | 1.205 (2) | C11—H11B | 0.99 |
C2—C3 | 1.472 (2) | C12—C15 | 1.510 (2) |
C3—C4 | 1.321 (3) | C12—H12 | 1.0 |
C3—C7 | 1.491 (2) | O13—C14 | 1.423 (2) |
C4—C5 | 1.495 (2) | C14—H14A | 0.98 |
C4—H4 | 0.95 | C14—H14B | 0.98 |
C5—C9 | 1.534 (3) | C14—H14C | 0.98 |
C5—H5 | 1.0 | C15—C16 | 1.387 (2) |
C7—H7A | 0.98 | C15—C20 | 1.398 (3) |
C7—H7B | 0.98 | C16—C17 | 1.388 (3) |
C7—H7C | 0.98 | C16—H16 | 0.95 |
N8—O13 | 1.4385 (19) | C17—C18 | 1.380 (4) |
N8—C9 | 1.477 (2) | C17—H17 | 0.95 |
N8—C12 | 1.479 (2) | C18—C19 | 1.382 (3) |
C9—C10 | 1.532 (2) | C18—H18 | 0.95 |
C9—H9 | 1.0 | C19—C20 | 1.390 (3) |
C10—C11 | 1.544 (2) | C19—H19 | 0.95 |
C10—H10A | 0.99 | C20—H20 | 0.95 |
C10—H10B | 0.99 | ||
C2—O1—C5 | 109.38 (12) | C12—C11—C10 | 106.28 (14) |
O6—C2—O1 | 121.57 (16) | C12—C11—H11A | 110.5 |
O6—C2—C3 | 129.46 (17) | C10—C11—H11A | 110.5 |
O1—C2—C3 | 108.97 (14) | C12—C11—H11B | 110.5 |
C4—C3—C2 | 107.40 (14) | C10—C11—H11B | 110.5 |
C4—C3—C7 | 131.73 (16) | H11A—C11—H11B | 108.7 |
C2—C3—C7 | 120.80 (16) | N8—C12—C15 | 110.73 (13) |
C3—C4—C5 | 110.71 (15) | N8—C12—C11 | 101.97 (13) |
C3—C4—H4 | 124.6 | C15—C12—C11 | 115.48 (15) |
C5—C4—H4 | 124.6 | N8—C12—H12 | 109.5 |
O1—C5—C4 | 103.55 (14) | C15—C12—H12 | 109.5 |
O1—C5—C9 | 110.83 (14) | C11—C12—H12 | 109.5 |
C4—C5—C9 | 114.14 (15) | C14—O13—N8 | 108.14 (13) |
O1—C5—H5 | 109.4 | O13—C14—H14A | 109.5 |
C4—C5—H5 | 109.4 | O13—C14—H14B | 109.5 |
C9—C5—H5 | 109.4 | H14A—C14—H14B | 109.5 |
C3—C7—H7A | 109.5 | O13—C14—H14C | 109.5 |
C3—C7—H7B | 109.5 | H14A—C14—H14C | 109.5 |
H7A—C7—H7B | 109.5 | H14B—C14—H14C | 109.5 |
C3—C7—H7C | 109.5 | C16—C15—C20 | 119.04 (17) |
H7A—C7—H7C | 109.5 | C16—C15—C12 | 120.38 (17) |
H7B—C7—H7C | 109.5 | C20—C15—C12 | 120.58 (16) |
O13—N8—C9 | 110.28 (13) | C15—C16—C17 | 120.55 (19) |
O13—N8—C12 | 108.44 (12) | C15—C16—H16 | 119.7 |
C9—N8—C12 | 106.87 (13) | C17—C16—H16 | 119.7 |
N8—C9—C10 | 100.89 (14) | C18—C17—C16 | 120.1 (2) |
N8—C9—C5 | 115.55 (14) | C18—C17—H17 | 120.0 |
C10—C9—C5 | 113.92 (14) | C16—C17—H17 | 120.0 |
N8—C9—H9 | 108.7 | C17—C18—C19 | 120.08 (19) |
C10—C9—H9 | 108.7 | C17—C18—H18 | 120.0 |
C5—C9—H9 | 108.7 | C19—C18—H18 | 120.0 |
C9—C10—C11 | 104.81 (13) | C18—C19—C20 | 120.1 (2) |
C9—C10—H10A | 110.8 | C18—C19—H19 | 119.9 |
C11—C10—H10A | 110.8 | C20—C19—H19 | 119.9 |
C9—C10—H10B | 110.8 | C19—C20—C15 | 120.10 (19) |
C11—C10—H10B | 110.8 | C19—C20—H20 | 120.0 |
H10A—C10—H10B | 108.9 | C15—C20—H20 | 120.0 |
C5—O1—C2—O6 | −179.35 (17) | C9—C10—C11—C12 | −7.74 (19) |
C5—O1—C2—C3 | −0.06 (19) | O13—N8—C12—C15 | −77.91 (17) |
O6—C2—C3—C4 | 179.44 (19) | C9—N8—C12—C15 | 163.22 (14) |
O1—C2—C3—C4 | 0.2 (2) | O13—N8—C12—C11 | 158.69 (13) |
O6—C2—C3—C7 | 2.1 (3) | C9—N8—C12—C11 | 39.81 (18) |
O1—C2—C3—C7 | −177.16 (15) | C10—C11—C12—N8 | −18.38 (18) |
C2—C3—C4—C5 | −0.3 (2) | C10—C11—C12—C15 | −138.50 (15) |
C7—C3—C4—C5 | 176.70 (18) | C9—N8—O13—C14 | −122.23 (14) |
C2—O1—C5—C4 | −0.11 (18) | C12—N8—O13—C14 | 121.07 (14) |
C2—O1—C5—C9 | −122.92 (14) | N8—C12—C15—C16 | 123.43 (18) |
C3—C4—C5—O1 | 0.25 (19) | C11—C12—C15—C16 | −121.35 (18) |
C3—C4—C5—C9 | 120.85 (17) | N8—C12—C15—C20 | −57.0 (2) |
O13—N8—C9—C10 | −162.41 (13) | C11—C12—C15—C20 | 58.3 (2) |
C12—N8—C9—C10 | −44.74 (17) | C20—C15—C16—C17 | 1.2 (3) |
O13—N8—C9—C5 | −39.07 (19) | C12—C15—C16—C17 | −179.20 (17) |
C12—N8—C9—C5 | 78.60 (18) | C15—C16—C17—C18 | −0.2 (3) |
O1—C5—C9—N8 | −69.67 (17) | C16—C17—C18—C19 | −0.9 (3) |
C4—C5—C9—N8 | 173.89 (15) | C17—C18—C19—C20 | 1.0 (3) |
O1—C5—C9—C10 | 46.50 (18) | C18—C19—C20—C15 | 0.0 (3) |
C4—C5—C9—C10 | −69.9 (2) | C16—C15—C20—C19 | −1.1 (3) |
N8—C9—C10—C11 | 30.75 (17) | C12—C15—C20—C19 | 179.31 (17) |
C5—C9—C10—C11 | −93.70 (17) |
Cg1 and Cg3 are the centroids of the O1/C2–C5 dihydrofuran and C15–C20 phenyl rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O1 | 1.00 | 2.40 | 2.957 (2) | 114 |
C5—H5···O13 | 1.00 | 2.42 | 2.791 (2) | 101 |
C10—H10B···Cg1 | 0.99 | 2.56 | 2.963 (2) | 104 |
C5—H5···O6i | 1.00 | 2.51 | 3.185 (2) | 125 |
C10—H10A···Cg1ii | 0.99 | 2.89 | 3.686 (2) | 138 |
C16—H16···Cg3iii | 0.95 | 2.99 | 3.761 (2) | 139 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) x+1/2, −y+1/2, −z+1. |
Cg1 and Cg3 are the centroids of the O1/C2–C5 dihydrofuran and C15–C20 phenyl rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O1 | 1.00 | 2.40 | 2.957 (2) | 114.2 |
C5—H5···O13 | 1.00 | 2.42 | 2.791 (2) | 101.3 |
C10—H10B···Cg1 | 0.99 | 2.56 | 2.963 (2) | 104 |
C5—H5···O6i | 1.00 | 2.51 | 3.185 (2) | 124.7 |
C10—H10A···Cg1ii | 0.99 | 2.89 | 3.686 (2) | 138 |
C16—H16···Cg3iii | 0.95 | 2.99 | 3.761 (2) | 139 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) x+1/2, −y+1/2, −z+1. |
Acknowledgements
We thank Professor S. Ohba (Keio University, Japan) for his valuable advice.
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A number of compounds containing oxidized nitrogen functionality have been widely used in organic synthesis. In these substances, the N-alkoxyamines are known as the initiators for the stable free radical polymerization (Hawker et al., 2001), and the N-alkoxyamides are utilized for mild and effective acylating agents (cf. Weinreb amide; Nahm & Weinreb, 1981). We noticed this inert N—O covalent bond, to develop a novel reaction to synthesize the natural alkaloids (Yanagita et al., 2013).
In the title compound, the dihydrofuran ring is planar with a maximum deviation of 0.0016 (11) Å at atom C4, and the pyrrolidine ring is in a twist conformation with puckering parameters of Q(2) = 0.4145 (18) Å and ϕ(2) = 10.6 (3)° (Cremer & Pople, 1975). Atoms N8 and C9 are deviated by –0.4566 (13) and 0.1991 (19) Å, respectively, from the plane of other carbon atoms (C10–C12). Angles of O13—N8—C9, O13—N8—C12 and C9—N8—C12 being 110.28 (13), 108.44 (12) and 106.87 (13)°, respectively, revealed the sp3 configuration of the N8 atom. The relative configurations were confirmed by the X-ray analysis as C5R, C9S and C12S.
The crystal packing iss stabilized by an intermolecular C5—H5···O6 (–x + 1, y + 1/2, –z + 3/2) hydrogen bond (Table 1), forming a helical chain along to the [010] direction (Fig. 2). Further intermolecular C—H···π interactions form a three-dimensional network in the crystal structure (Fig. 3). Distances for C10—H10A···Cg1 (x – 1, y, z) and C16—H···Cg3 (x + 1/2, –y + 1/2, –z + 1) are 3.686 (2) and 3.761 (2) Å, respectively. Cg1 and Cg3 are the centroids of the O1/C2–C5 dihydrofuran and C15–C20 phenyl rings, respectively. Additionally, weak intramolecular interactions, C12—H···O1, C5—H···O13 and C10—H10B···Cg1 being 2.957 (2), 2.791 (2) and 2.963 (2) Å, respectively, adopt the molecule into a sterically hindered conformation. The C5—O1 bond of dihydrofuran is overhanged on the pyrrolidine ring, with torsion angles of O1—C5—C9—N8 and O1—C5—C9—C10 being –69.7 (2) and 46.5 (2)°, respectively (Fig. 4).