(E)-1-[1-(3-Phenyl­cyclo­penta-2,4-dien-1-yl­idene)eth­yl]pyrrolidine

Peloquin, A.J.; Smith, M.B.; Balaich, G.J.; Iacono, S.T.

doi:10.1107/S2414314618007642

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 6| June 2018| x180764

https://doi.org/10.1107/S2414314618007642

Open

access

(E)-1-[1-(3-Phenylcyclopenta-2,4-dien-1-ylidene)ethyl]pyrrolidine

Andrew J. Peloquin,^a Madelyn B. Smith,^a Gary J. Balaich ^a and Scott T. Iacono ^a ^*

^aDepartment of Chemistry & Chemistry Research Center, United States Air Force, Academy, Colorado Springs, CO 80840, USA
^*Correspondence e-mail: scott.iacono@usafa.edu

Edited by J. Simpson, University of Otago, New Zealand (Received 2 May 2018; accepted 22 May 2018; online 5 June 2018)

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 space group P2₁/n with one molecule in the asymmetric unit. 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.

Table 1
Hydrogen-bond geometry (Å, °)

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) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) -x, -y+2, -z; (iii) -x, -y+1, -z.

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are shown at the 50% probability level.

Figure 2
The crystal packing of the title compound, viewed along the a axis. Displacement ellipsoids are shown at the 50% probability level. C—H⋯π ring interactions are shown as dashed lines.

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.

Figure 3
Reaction scheme.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₇H₁₉N
M_r	237.33
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	6.7724 (13), 7.1774 (14), 26.793 (5)
β (°)	93.184 (3)
V (Å³)	1300.3 (4)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.07
Crystal size (mm)	0.44 × 0.33 × 0.26

Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2017 )
T_min, T_max	0.82, 0.98
No. of measured, independent and observed [I > 2σ(I)] reflections	14212, 3185, 2252
R_int	0.054
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.054, 0.132, 1.03
No. of reflections	3185
No. of parameters	164
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.23
Computer programs: APEX3 (Bruker, 2017), SAINT (Bruker, 2017), SHELXT (Sheldrick, 2015a ), SHELXL2016 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ) and Mercury (Macrae et al., 2008 ), publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1844781

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314618007642/sj4179sup1.cif

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

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2017); cell refinement: 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).

(E)-1-[1-(3-Phenylcyclopenta-2,4-dien-1-ylidene)ethyl]pyrrolidine top

Crystal data top

C₁₇H₁₉N	F(000) = 512
M_r = 237.33	D_x = 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

Data collection top

Bruker SMART APEX CCD diffractometer	3185 independent reflections
Radiation source: fine focus sealed tube	2252 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.054
Detector resolution: 8.3333 pixels mm^-1	θ_max = 28.3°, θ_min = 3.1°
ω scans	h = −9→8
Absorption correction: multi-scan (SADABS; Bruker, 2017)	k = −9→9
T_min = 0.82, T_max = 0.98	l = −35→35
14212 measured reflections

Refinement top

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(F_o²) + (0.0459P)² + 0.5603P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max = 0.001
3185 reflections	Δρ_max = 0.30 e Å⁻³
164 parameters	Δρ_min = −0.23 e Å⁻³

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
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*

Atomic displacement parameters (Å²) top

	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)

Geometric parameters (Å, º) top

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

Hydrogen-bond geometry (Å, º) top

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) .

References

Bruker (2017). APEX3 and SAINT. Bruker–Nonius AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.