organic compounds
(E)-1-[1-(3-Phenylcyclopenta-2,4-dien-1-ylidene)ethyl]pyrrolidine
aDepartment of Chemistry & Chemistry Research Center, United States Air Force, Academy, Colorado Springs, CO 80840, USA
*Correspondence e-mail: scott.iacono@usafa.edu
The title compound, C17H19N, is a disubstituted pentafulvene obtained from the hydroamination of 1-phenyl-3-trimethylsilylethynylcyclopentadiene and has monoclinic P21/n symmetry at 100 K. C—H⋯π ring interactions between neighboring molecules consolidate the packing. To the authors' knowledge, this reaction is the first reported example of a non-transition metal catalyzed hydroamination with concomitant desilylation.
Keywords: crystal structure; hydroamination; fulvene.
CCDC reference: 1844781
Structure description
The title compound (Fig. 1) crystallizes in the monoclinic P21/n with one molecule in the Within the fulvene system, the expected alternating short and long bond distances as well as intra-ring bond angles were observed. The 2-phenyl substituent is rotated 24.24 (6)° from the fulvene plane. The geometry around N1 is trigonal planar and the N1/C14/C17 plane is rotated by only 15.42 (9)° from the fulvene plane, presumably to allow partial conjugation of the nitrogen lone pair into the fulvene π system. Only two broad peaks are observed for the pyrrolidine methylene protons in the 1H NMR spectrum, indicating N—C bond rotation and nitrogen inversion on the NMR timescale. C—H⋯π ring interactions (Table 1, Fig. 2) between neighboring molecules consolidate the packing.
Synthesis and crystallization
Synthesis of 1-phenyl-3-trimethylsilylethynylcyclopentadiene. To a vigorously stirred solution of ethynyltrimethylsilane (7.0 ml, 50.6 mmol) in anhydrous Et2O (25 ml) at −94°C under N2, n-BuLi (2.5 M, 19.2 ml, 48.0 mmol) was added dropwise over 20 min. and allowed to stir for 1 h. A solution of 3-phenylcyclopent-2-en-1-one (3.99 g, 25.2 mmol) in anhydrous Et2O (250 ml) was added dropwise over 20 min. The resulting solution was allowed to come to room temperature and stirred under N2 for 24 h, then exposed to air. The solvent was removed by rotary evaporation and the residue dissolved in CH2Cl2 (100 ml). 1 M H2SO4 (100 ml, 100 mmol) was added and allowed to stir for 1 h. The CH2Cl2 layer was separated and washed sequentially with NaHCO3 (3 × 50 ml), water (2 × 50 ml), and saturated brine (1 × 50 ml). The organic layer was dried over anhydrous MgSO4, filtered, and concentrated under vacuum to afford a red–yellow solid, which was recrystallized from ethanol (100 ml) to yield a pale-yellow solid (2.42 g, 40%). 1H NMR (500 MHz, CDCl3): δ 7.53–7.20 (m, 6H), 6.56 (m, 1H), 3.35 (m, 2H), 0.23 (s, 9H). 13C NMR (500 MHz, CDCl3): δ 146.0, 139.0, 134.9, 128.7, 128.5, 128.2, 127.7, 127.6, 126.0, 125.3, 102.1, 98.1, 46.1, 0.13.
Synthesis of (E)-1-(1-(3-phenylcyclopenta-2,4-dien-1-ylidene)ethyl)pyrrolidine. To a vigorously stirred solution of 1-phenyl-3-trimethylsilylethynylcyclopentadiene (0.336 g, 1.42 mmol) in absolute EtOH (8 ml), pyrrolidine (0.14 ml, 1.70 mmol) was added (Fig. 3). An immediate color change from pale yellow to golden brown was observed. The reaction mixture was allowed to stir at room temperature for 5 h, then to stand for 48 h. During this time, yellow, needle-like crystals of the product fulvene formed, and were isolated by vacuum filtration (0.21 g, 63%). 1H NMR (500 MHz, CDCl3): δ 7.65 (dd, 2H, J1 = 8 Hz, J2 = 1.5 Hz), 7.32 (t, 2H, J = 7.5 Hz), 7.15–7.11 (m, 1H), 3.77 (s, 4H), 2.56 (d, 3H, J = 15 Hz), 2.04 (s, 4H). 13C NMR (500 MHz, CDCl3): δ 156.3, 138.9, 136.2, 133.3, 128.4, 125.3, 121.3, 118.8,115.6, 112.2, 51.9, 25.5, 21.2.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 1844781
https://doi.org/10.1107/S2414314618007642/sj4179sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618007642/sj4179Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314618007642/sj4179Isup3.cml
Data collection: APEX3 (Bruker, 2017); cell
SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).C17H19N | F(000) = 512 |
Mr = 237.33 | Dx = 1.212 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 6.7724 (13) Å | Cell parameters from 2164 reflections |
b = 7.1774 (14) Å | θ = 2.9–29.9° |
c = 26.793 (5) Å | µ = 0.07 mm−1 |
β = 93.184 (3)° | T = 100 K |
V = 1300.3 (4) Å3 | Needle, translucent yellow |
Z = 4 | 0.44 × 0.33 × 0.26 mm |
Bruker SMART APEX CCD diffractometer | 3185 independent reflections |
Radiation source: fine focus sealed tube | 2252 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.054 |
Detector resolution: 8.3333 pixels mm-1 | θmax = 28.3°, θmin = 3.1° |
ω scans | h = −9→8 |
Absorption correction: multi-scan (SADABS; Bruker, 2017) | k = −9→9 |
Tmin = 0.82, Tmax = 0.98 | l = −35→35 |
14212 measured reflections |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.054 | H-atom parameters constrained |
wR(F2) = 0.132 | w = 1/[σ2(Fo2) + (0.0459P)2 + 0.5603P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
3185 reflections | Δρmax = 0.30 e Å−3 |
164 parameters | Δρmin = −0.23 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.61400 (18) | 0.80353 (18) | 0.44578 (5) | 0.0216 (3) | |
C1 | 0.5199 (2) | 0.6602 (2) | 0.57666 (6) | 0.0216 (3) | |
H1 | 0.382106 | 0.636262 | 0.577195 | 0.026* | |
C2 | 0.6539 (2) | 0.6400 (2) | 0.61681 (6) | 0.0227 (3) | |
C3 | 0.8437 (2) | 0.6917 (2) | 0.60003 (6) | 0.0259 (4) | |
H3 | 0.963888 | 0.691376 | 0.620061 | 0.031* | |
C4 | 0.8249 (2) | 0.7413 (2) | 0.55085 (6) | 0.0240 (3) | |
H4 | 0.929248 | 0.781084 | 0.531106 | 0.029* | |
C5 | 0.6195 (2) | 0.7230 (2) | 0.53385 (6) | 0.0204 (3) | |
C6 | 0.5240 (2) | 0.7603 (2) | 0.48717 (6) | 0.0202 (3) | |
C7 | 0.6129 (2) | 0.5764 (2) | 0.66719 (6) | 0.0245 (4) | |
C8 | 0.4256 (3) | 0.5944 (2) | 0.68581 (6) | 0.0286 (4) | |
H8 | 0.322051 | 0.649477 | 0.665473 | 0.034* | |
C9 | 0.3875 (3) | 0.5334 (3) | 0.73339 (7) | 0.0348 (4) | |
H9 | 0.258614 | 0.546292 | 0.745281 | 0.042* | |
C10 | 0.5364 (3) | 0.4538 (3) | 0.76354 (7) | 0.0392 (5) | |
H10 | 0.510707 | 0.411977 | 0.796189 | 0.047* | |
C11 | 0.7229 (3) | 0.4356 (3) | 0.74589 (7) | 0.0361 (4) | |
H11 | 0.826046 | 0.381445 | 0.76657 | 0.043* | |
C12 | 0.7609 (3) | 0.4953 (2) | 0.69846 (6) | 0.0303 (4) | |
H12 | 0.889963 | 0.480998 | 0.686822 | 0.036* | |
C13 | 0.3032 (2) | 0.7549 (2) | 0.48095 (6) | 0.0243 (3) | |
H13A | 0.253437 | 0.878064 | 0.470704 | 0.036* | |
H13B | 0.248508 | 0.720008 | 0.512746 | 0.036* | |
H13C | 0.262881 | 0.662932 | 0.455323 | 0.036* | |
C14 | 0.8271 (2) | 0.7903 (2) | 0.43937 (6) | 0.0251 (4) | |
H14A | 0.882633 | 0.675685 | 0.455208 | 0.03* | |
H14B | 0.897478 | 0.899698 | 0.454144 | 0.03* | |
C15 | 0.8436 (3) | 0.7848 (3) | 0.38320 (6) | 0.0322 (4) | |
H15A | 0.831669 | 0.655811 | 0.370312 | 0.039* | |
H15B | 0.970807 | 0.838305 | 0.373602 | 0.039* | |
C16 | 0.6702 (3) | 0.9039 (3) | 0.36401 (7) | 0.0349 (4) | |
H16A | 0.703317 | 1.038045 | 0.366376 | 0.042* | |
H16B | 0.63124 | 0.873165 | 0.328811 | 0.042* | |
C17 | 0.5070 (2) | 0.8549 (2) | 0.39806 (6) | 0.0258 (4) | |
H17A | 0.418844 | 0.962931 | 0.402617 | 0.031* | |
H17B | 0.427141 | 0.749132 | 0.384447 | 0.031* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0229 (6) | 0.0207 (7) | 0.0214 (7) | 0.0000 (5) | 0.0025 (5) | −0.0006 (5) |
C1 | 0.0233 (7) | 0.0181 (8) | 0.0238 (8) | −0.0006 (6) | 0.0041 (6) | −0.0021 (6) |
C2 | 0.0271 (8) | 0.0178 (8) | 0.0232 (8) | 0.0017 (6) | 0.0016 (6) | −0.0025 (6) |
C3 | 0.0240 (8) | 0.0272 (9) | 0.0261 (9) | 0.0014 (6) | −0.0015 (6) | −0.0027 (7) |
C4 | 0.0207 (7) | 0.0230 (8) | 0.0285 (9) | −0.0001 (6) | 0.0036 (6) | −0.0013 (7) |
C5 | 0.0209 (7) | 0.0170 (8) | 0.0233 (8) | 0.0005 (6) | 0.0029 (6) | −0.0007 (6) |
C6 | 0.0224 (7) | 0.0152 (7) | 0.0233 (8) | 0.0004 (6) | 0.0040 (6) | −0.0026 (6) |
C7 | 0.0341 (9) | 0.0182 (8) | 0.0210 (8) | −0.0008 (6) | 0.0005 (6) | −0.0034 (6) |
C8 | 0.0349 (9) | 0.0259 (9) | 0.0250 (9) | 0.0006 (7) | 0.0026 (7) | 0.0000 (7) |
C9 | 0.0427 (10) | 0.0352 (10) | 0.0276 (9) | −0.0018 (8) | 0.0107 (8) | 0.0009 (8) |
C10 | 0.0590 (12) | 0.0339 (10) | 0.0250 (10) | 0.0008 (9) | 0.0060 (8) | 0.0052 (8) |
C11 | 0.0516 (11) | 0.0285 (9) | 0.0276 (10) | 0.0046 (8) | −0.0037 (8) | 0.0039 (7) |
C12 | 0.0381 (9) | 0.0240 (9) | 0.0288 (9) | 0.0032 (7) | 0.0003 (7) | −0.0003 (7) |
C13 | 0.0217 (7) | 0.0257 (8) | 0.0256 (8) | 0.0009 (6) | 0.0016 (6) | 0.0003 (7) |
C14 | 0.0230 (8) | 0.0266 (9) | 0.0262 (9) | −0.0017 (6) | 0.0058 (6) | −0.0009 (7) |
C15 | 0.0341 (9) | 0.0346 (10) | 0.0288 (9) | 0.0006 (7) | 0.0106 (7) | 0.0016 (7) |
C16 | 0.0421 (10) | 0.0351 (10) | 0.0283 (10) | 0.0065 (8) | 0.0104 (8) | 0.0070 (8) |
C17 | 0.0315 (8) | 0.0228 (8) | 0.0232 (9) | 0.0022 (7) | 0.0014 (6) | −0.0004 (6) |
N1—C6 | 1.331 (2) | C10—C11 | 1.379 (3) |
N1—C14 | 1.4658 (19) | C10—H10 | 0.95 |
N1—C17 | 1.481 (2) | C11—C12 | 1.379 (2) |
C1—C2 | 1.376 (2) | C11—H11 | 0.95 |
C1—C5 | 1.435 (2) | C12—H12 | 0.95 |
C1—H1 | 0.95 | C13—H13A | 0.98 |
C2—C3 | 1.434 (2) | C13—H13B | 0.98 |
C2—C7 | 1.466 (2) | C13—H13C | 0.98 |
C3—C4 | 1.364 (2) | C14—C15 | 1.516 (2) |
C3—H3 | 0.95 | C14—H14A | 0.99 |
C4—C5 | 1.446 (2) | C14—H14B | 0.99 |
C4—H4 | 0.95 | C15—C16 | 1.519 (2) |
C5—C6 | 1.402 (2) | C15—H15A | 0.99 |
C6—C13 | 1.496 (2) | C15—H15B | 0.99 |
C7—C8 | 1.395 (2) | C16—C17 | 1.513 (2) |
C7—C12 | 1.397 (2) | C16—H16A | 0.99 |
C8—C9 | 1.386 (2) | C16—H16B | 0.99 |
C8—H8 | 0.95 | C17—H17A | 0.99 |
C9—C10 | 1.381 (3) | C17—H17B | 0.99 |
C9—H9 | 0.95 | ||
C6—N1—C14 | 125.57 (13) | C10—C11—H11 | 119.8 |
C6—N1—C17 | 123.53 (13) | C11—C12—C7 | 121.21 (16) |
C14—N1—C17 | 110.66 (12) | C11—C12—H12 | 119.4 |
C2—C1—C5 | 109.85 (14) | C7—C12—H12 | 119.4 |
C2—C1—H1 | 125.1 | C6—C13—H13A | 109.5 |
C5—C1—H1 | 125.1 | C6—C13—H13B | 109.5 |
C1—C2—C3 | 106.92 (14) | H13A—C13—H13B | 109.5 |
C1—C2—C7 | 127.05 (14) | C6—C13—H13C | 109.5 |
C3—C2—C7 | 126.02 (14) | H13A—C13—H13C | 109.5 |
C4—C3—C2 | 109.48 (14) | H13B—C13—H13C | 109.5 |
C4—C3—H3 | 125.3 | N1—C14—C15 | 104.22 (13) |
C2—C3—H3 | 125.3 | N1—C14—H14A | 110.9 |
C3—C4—C5 | 108.49 (14) | C15—C14—H14A | 110.9 |
C3—C4—H4 | 125.8 | N1—C14—H14B | 110.9 |
C5—C4—H4 | 125.8 | C15—C14—H14B | 110.9 |
C6—C5—C1 | 124.02 (14) | H14A—C14—H14B | 108.9 |
C6—C5—C4 | 130.70 (14) | C14—C15—C16 | 102.90 (14) |
C1—C5—C4 | 105.26 (13) | C14—C15—H15A | 111.2 |
N1—C6—C5 | 125.31 (14) | C16—C15—H15A | 111.2 |
N1—C6—C13 | 114.48 (13) | C14—C15—H15B | 111.2 |
C5—C6—C13 | 120.20 (14) | C16—C15—H15B | 111.2 |
C8—C7—C12 | 117.41 (15) | H15A—C15—H15B | 109.1 |
C8—C7—C2 | 121.55 (14) | C17—C16—C15 | 104.02 (13) |
C12—C7—C2 | 121.04 (15) | C17—C16—H16A | 111.0 |
C9—C8—C7 | 121.30 (16) | C15—C16—H16A | 111.0 |
C9—C8—H8 | 119.3 | C17—C16—H16B | 111.0 |
C7—C8—H8 | 119.3 | C15—C16—H16B | 111.0 |
C10—C9—C8 | 120.11 (17) | H16A—C16—H16B | 109.0 |
C10—C9—H9 | 119.9 | N1—C17—C16 | 103.85 (13) |
C8—C9—H9 | 119.9 | N1—C17—H17A | 111.0 |
C11—C10—C9 | 119.47 (17) | C16—C17—H17A | 111.0 |
C11—C10—H10 | 120.3 | N1—C17—H17B | 111.0 |
C9—C10—H10 | 120.3 | C16—C17—H17B | 111.0 |
C12—C11—C10 | 120.50 (17) | H17A—C17—H17B | 109.0 |
C12—C11—H11 | 119.8 |
Cg2 and Cg3 are the centroids of the C1–C5 and C7–C12 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C11—H11···Cg3i | 0.95 | 2.75 | 3.4505 (7) | 131 |
C13—H13C···Cg2ii | 0.98 | 2.70 | 3.5435 (7) | 145 |
C17—H17A···Cg2iii | 0.99 | 2.67 | 3.6104 (7) | 159 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x, −y+2, −z; (iii) −x, −y+1, −z. |
Funding information
Funding for this research was provided by: Defense Threat Reduction Agency (DTRA) - Joint Science and Technology Transfer Office for Chemical and Biological Defense ; Air Force Office of Scientific Research (AFOSR) .
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