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Acta Crystallogr Sect E Struct Rep Online. 2010 July 1; 66(Pt 7): o1532.
Published online 2010 June 5. doi:  10.1107/S1600536810019975
PMCID: PMC3007022

1-[(E)-4-(5-Bromo-1H-indol-3-yl)-1-methyl-2,5,6,7-tetra­hydro-1H-azepin-2-yl­idene]propan-2-one

Abstract

In the title compound, C18H19BrN2O, the seven-membered azepine ring adopts a twist-boat conformation: the bond angles about the azepine N atom are indicative of sp 2 hybridization. The dihedral angle between the plane of the carbon–carbon double bond of the enone unit and the mean plane of the indole ring is 27.8 (1)°. In the crystal, an N—H(...)O hydrogen bond links the mol­ecules into chains along the b axis.

Related literature

For structure intrepretation tools, see: Allen (2002 [triangle]); Allen et al. (1993 [triangle]); Cremer & Pople (1975 [triangle]). For the reaction chemistry of (Z)-3-(1-methyl­pyrrolidin-2-yl­idene)-3H-indole, see: Bishop et al. (1981a [triangle],b [triangle], 1982a [triangle],b [triangle]); Harris & Joule (1978a [triangle],b [triangle]).

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Object name is e-66-o1532-scheme1.jpg

Experimental

Crystal data

  • C18H19BrN2O
  • M r = 359.26
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1532-efi1.jpg
  • a = 14.496 (2) Å
  • b = 6.6677 (10) Å
  • c = 16.372 (3) Å
  • β = 90.267 (2)°
  • V = 1582.4 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 2.60 mm−1
  • T = 100 K
  • 0.30 × 0.20 × 0.20 mm

Data collection

  • Bruker APEX CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.829, T max = 1.000
  • 12098 measured reflections
  • 3239 independent reflections
  • 3021 reflections with I > 2σ(I)
  • R int = 0.023

Refinement

  • R[F 2 > 2σ(F 2)] = 0.027
  • wR(F 2) = 0.069
  • S = 1.25
  • 3239 reflections
  • 205 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.39 e Å−3
  • Δρmin = −0.23 e Å−3

Data collection: SMART (Bruker, 2001 [triangle]); cell refinement: SAINT (Bruker, 2002 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]) and PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: SHELXTL and PLATON.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810019975/jj2030sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810019975/jj2030Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors are grateful to the University of Urmia for financial support of the preparative aspects of this work. MA thanks the Daana Pharmaceutical Co (Tabriz-Iran) for the infrared spectra.

supplementary crystallographic information

Comment

Study of the reaction chemistry of (Z)-3-(1-methylpyrrolidin-2-ylidene)-3H-indole has revealed some remarkable properties and transformations. For example, it was shown to be a remarkably strong base, pKa 10.6, for an imine, to be compared with that for 4a-methyl-1,2,3,4-tetrahydro-4a(i)H-carbazole with a pKa of 3.6 (Harris and Joule, 1978a,b). It reacts with pentane-2,4-dione to give ((E)-4-(1H-indol-3-yl)- 2,5,6,7-tetrahydro-1-methyl-1H-azepin-2-ylidene)propan-2-one via an extensive rearrangement (Bishop et al., 1981a,b). In addition, it reacts with diethyl malonate giving 7-(2-aminophenyl)-5-ethoxycarbonyl-2,3-dihydro-4-hydroxy-1-methylindole, involving another extensive and unprecedented rearrangement (Bishop et al., 1982a,b). We detail here the crystal structure of the product ,(I), C18H19BrN2, formed by reacting (Z)-5-bromo-3-(1-methylpyrrolidin-2-ylidene)-3H-indole with pentane-2,4-dione following the procedure for the des-bromo-prototype (Bishop et al., 1981a,b), (Fig. 1), leading to a 5-bromoindol-3-yl-substituted tetrahydroazepine, (I).

The seven-membered azepine ring adopts a twist-boat conformation as shown by the puckering parameters (Cremer & Pople, 1975; Allen et al., 1993) q2= 1.008 (2); q3= 0.176 (2); [var phi]2= 298.0 (1); [var phi]3 = 34.4 (6) ° (Spek, 2009), Fig.2. Bond distances and angles in (I) are in the normal range (Allen, 2002). The planar 5-bromoindole bicycle is not coplanar with the enone in the seven-membered azepine ring. The dihedral angle between the enone double bond and the mean plane of the indole ring is 27.8 (1) °. The azepine nitrogen is sp2 hybridized, with the sum of the angles around it being 359.4 °, indicating its conjugating interaction with the exocyclic enone, i.e. it is a vinylogous amide nitrogen. The exocyclic double bond has E geometry. A N1—H1···O1 hydrogen bond between the indole ring and the carbonyl group extending from the propan-2-one group links the molecules into chains along the b axis (Fig. 3).

Experimental

(Z)-5-Bromo-3-(1-methylpyrrolidin-2-ylidene)-3H-indole (0.5 g, 1.8 mmol) was heated in refluxing pentane-2,4-dione (11 ml) for 4 h (Fig. 1). When excess diketone was removed by distillation under vacuum, a yellow solid was obtained which was partitioned between 2M HCl and ethyl acetate. The basic product was isolated from the aqueous acidic layer by basification with potassium carbonate and extraction with dichloromethane (0.48 g, 78%). The product was recrystallized in n-hexane/ethanol to give yellow crystalline material, mp 459–461 K.

Refinement

H atoms bonded to C were included in calculated positions using the riding method, with aromatic, methylene and methyl C—H distances of 0.98, 0.99 and 0.95 Å, respectively and U~eq ~values 1.2 and 1.5 times those of the parent atoms; the torsion angles of the methyl H atoms were optimized to give the best fit to the electron density. The H atom bonded to N1 was found by difference Fourier methods and refined isotropically with N–H = 0.78 (2) Å.

Figures

Fig. 1.
The reaction scheme for 5-bromo-3-(1-methylpyrrolidin-2-ylidene)-3H -indole with pentane-2,4-dione to form (I), C18H19BrN2.
Fig. 2.
The structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level.
Fig. 3.
Packing arrangement of (I) viewed down a. Dashed lines indicate N—H···O hydrogen bonds between the indole ring and the carbonyl group extending from the propan-2-one group linking the molecules into chains along the c axis. ...

Crystal data

C18H19BrN2OF(000) = 736
Mr = 359.26Dx = 1.508 Mg m3
Monoclinic, P21/nMelting point = 459–461 K
Hall symbol: -P 2ynMo Kα radiation, λ = 0.71073 Å
a = 14.496 (2) ÅCell parameters from 915 reflections
b = 6.6677 (10) Åθ = 2.8–26.4°
c = 16.372 (3) ŵ = 2.60 mm1
β = 90.267 (2)°T = 100 K
V = 1582.4 (4) Å3Block, yellow
Z = 40.30 × 0.20 × 0.20 mm

Data collection

Bruker APEX CCD area-detector diffractometer3239 independent reflections
Radiation source: fine-focus sealed tube3021 reflections with I > 2σ(I)
graphiteRint = 0.023
Detector resolution: 8.33 pixels mm-1θmax = 26.4°, θmin = 1.9°
[var phi] and ω scansh = −17→18
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)k = −8→8
Tmin = 0.829, Tmax = 1.000l = −20→20
12098 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.069H atoms treated by a mixture of independent and constrained refinement
S = 1.25w = 1/[σ2(Fo2) + (0.0342P)2 + 0.3299P] where P = (Fo2 + 2Fc2)/3
3239 reflections(Δ/σ)max = 0.031
205 parametersΔρmax = 0.39 e Å3
0 restraintsΔρmin = −0.23 e Å3

Special details

Experimental. 1H-NMR (CDCl3) δ (ppm) 2.0 (2H, qn, J = 6.6 Hz, azepin-6-yl-H2), 2.18 (3H, s, MeCO overlying 2H, m, azepin-5-yl-H2),), 3.14 (1H, s, MeN), 3.41 (2H, t, J = 6.3 Hz, azepin-7-yl-H2), 5.19 (1H, s, exocyclic =CH), 6.35 (1H, s, azepin-3-yl-H), 7.0 (1H, d, J = 8.7 Hz, ArH), 7.13 (1H, d, J = 8.7 Hz, ArH), 7.23 (1H, s, indol-4-yl-H), 7.93 (1H, s, indol-2-yl-H), 11.12 (1H, bs, NH). 13C-NMR (CDCl3) δ 28.8, 31.1, 31.4, 39.7, 52.2, 94.6, 113.4, 113.6, 119.6, 122.4, 124.2, 126.4, 127.1, 134.5, 141.3, 163.9, 193.4. νmax 2915, 1611, 1506, 1340, 1189, 972, 787. λmax (EtOH) 236, 261, 350 nm.
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 on F2 against ALL reflections. Weighted R-factors wR and all goodnesses 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)

xyzUiso*/Ueq
Br10.545967 (12)1.20143 (3)0.175612 (11)0.01975 (8)
O10.13649 (9)0.9119 (2)0.03015 (7)0.0188 (3)
N10.35260 (10)0.4764 (2)0.30389 (9)0.0153 (3)
N20.29940 (10)0.4751 (2)−0.09752 (9)0.0140 (3)
C10.30698 (11)0.4879 (3)0.08357 (10)0.0130 (3)
C20.28922 (11)0.6432 (3)0.03283 (10)0.0135 (3)
H20.29620.77490.05420.016*
C30.26004 (11)0.6240 (3)−0.05267 (10)0.0131 (3)
C40.38380 (12)0.3749 (3)−0.06878 (10)0.0161 (4)
H4A0.42460.4753−0.04250.019*
H4B0.41690.3188−0.11630.019*
C50.36434 (14)0.2070 (3)−0.00819 (11)0.0179 (4)
H5A0.42230.16880.02000.021*
H5B0.34100.0879−0.03790.021*
C60.29263 (13)0.2741 (3)0.05526 (11)0.0165 (4)
H6A0.23010.26160.03110.020*
H6B0.29600.18360.10310.020*
C70.33667 (11)0.5212 (3)0.16813 (10)0.0122 (3)
C80.38650 (11)0.6899 (2)0.20169 (10)0.0118 (3)
C90.43010 (11)0.8588 (3)0.16825 (10)0.0135 (3)
H90.42740.88530.11130.016*
C100.47689 (12)0.9849 (3)0.22064 (11)0.0151 (3)
C110.47997 (12)0.9571 (3)0.30543 (11)0.0180 (4)
H110.51061.05210.33930.022*
C120.43834 (13)0.7910 (3)0.33961 (11)0.0170 (4)
H120.43960.76890.39690.020*
C130.39445 (11)0.6568 (3)0.28686 (10)0.0138 (3)
C140.31950 (11)0.3958 (3)0.23342 (10)0.0146 (3)
H140.28870.27030.22960.017*
C150.19750 (12)0.7566 (3)−0.08831 (10)0.0147 (3)
H150.18970.7498−0.14590.018*
C160.14431 (11)0.9017 (3)−0.04539 (10)0.0143 (3)
C170.09459 (12)1.0600 (3)−0.09551 (11)0.0181 (4)
H17A0.03101.0732−0.07620.027*
H17B0.09411.0201−0.15310.027*
H17C0.12651.1887−0.08960.027*
C180.26809 (13)0.4286 (3)−0.18007 (10)0.0183 (4)
H18A0.20070.4375−0.18260.027*
H18B0.28750.2925−0.19460.027*
H18C0.29500.5246−0.21850.027*
H1N0.3516 (15)0.431 (3)0.3474 (14)0.023 (6)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br10.02014 (12)0.01765 (12)0.02146 (12)−0.00671 (7)−0.00231 (8)0.00178 (7)
O10.0215 (6)0.0241 (7)0.0106 (6)0.0039 (5)−0.0001 (5)−0.0015 (5)
N10.0172 (7)0.0186 (8)0.0102 (7)−0.0021 (6)−0.0003 (6)0.0039 (6)
N20.0162 (7)0.0159 (7)0.0099 (7)0.0025 (6)−0.0014 (5)−0.0004 (6)
C10.0106 (8)0.0158 (8)0.0125 (8)−0.0015 (6)0.0008 (6)−0.0009 (7)
C20.0116 (8)0.0157 (8)0.0132 (8)−0.0010 (6)−0.0004 (6)−0.0017 (7)
C30.0131 (8)0.0146 (8)0.0116 (8)−0.0038 (7)0.0006 (6)0.0005 (7)
C40.0178 (9)0.0164 (9)0.0140 (8)0.0028 (7)0.0012 (7)0.0013 (7)
C50.0249 (10)0.0130 (9)0.0158 (9)0.0016 (7)−0.0007 (8)−0.0005 (7)
C60.0218 (9)0.0151 (9)0.0126 (8)−0.0036 (7)−0.0010 (7)0.0013 (7)
C70.0097 (8)0.0147 (8)0.0122 (8)0.0019 (6)0.0000 (6)0.0001 (6)
C80.0099 (8)0.0143 (8)0.0112 (8)0.0029 (6)0.0002 (6)−0.0004 (6)
C90.0124 (8)0.0160 (8)0.0121 (8)0.0016 (7)0.0000 (6)0.0000 (7)
C100.0127 (8)0.0140 (8)0.0186 (9)−0.0002 (6)−0.0002 (7)0.0012 (7)
C110.0180 (9)0.0200 (9)0.0160 (9)−0.0019 (7)−0.0037 (7)−0.0040 (7)
C120.0170 (9)0.0217 (10)0.0124 (8)0.0018 (7)−0.0017 (7)−0.0007 (7)
C130.0109 (8)0.0174 (8)0.0129 (8)0.0011 (7)−0.0002 (6)0.0011 (7)
C140.0133 (8)0.0160 (9)0.0144 (8)−0.0002 (7)−0.0009 (6)0.0006 (7)
C150.0159 (9)0.0191 (8)0.0092 (8)−0.0011 (7)−0.0023 (7)0.0006 (7)
C160.0123 (8)0.0161 (9)0.0145 (8)−0.0028 (7)−0.0015 (6)−0.0001 (7)
C170.0184 (9)0.0200 (9)0.0158 (9)0.0028 (7)−0.0012 (7)0.0018 (7)
C180.0230 (9)0.0185 (9)0.0134 (8)−0.0002 (7)−0.0013 (7)−0.0038 (7)

Geometric parameters (Å, °)

Br1—C101.9073 (17)C7—C141.381 (2)
O1—C161.244 (2)C7—C81.444 (2)
N1—C141.358 (2)C8—C91.404 (2)
N1—C131.376 (2)C8—C131.416 (2)
N1—H1N0.78 (2)C9—C101.377 (2)
N2—C31.362 (2)C9—H90.9500
N2—C181.457 (2)C10—C111.401 (2)
N2—C41.469 (2)C11—C121.381 (3)
C1—C21.352 (2)C11—H110.9500
C1—C71.465 (2)C12—C131.395 (2)
C1—C61.513 (2)C12—H120.9500
C2—C31.466 (2)C14—H140.9500
C2—H20.9500C15—C161.424 (2)
C3—C151.393 (2)C15—H150.9500
C4—C51.523 (2)C16—C171.517 (2)
C4—H4A0.9900C17—H17A0.9800
C4—H4B0.9900C17—H17B0.9800
C5—C61.540 (3)C17—H17C0.9800
C5—H5A0.9900C18—H18A0.9800
C5—H5B0.9900C18—H18B0.9800
C6—H6A0.9900C18—H18C0.9800
C6—H6B0.9900
C14—N1—C13109.16 (15)C13—C8—C7106.97 (15)
C14—N1—H1N128.0 (17)C10—C9—C8117.91 (15)
C13—N1—H1N122.8 (17)C10—C9—H9121.0
C3—N2—C18121.71 (14)C8—C9—H9121.0
C3—N2—C4120.60 (14)C9—C10—C11123.34 (16)
C18—N2—C4117.12 (14)C9—C10—Br1118.64 (13)
C2—C1—C7121.26 (15)C11—C10—Br1117.95 (13)
C2—C1—C6120.54 (15)C12—C11—C10119.71 (16)
C7—C1—C6118.15 (15)C12—C11—H11120.1
C1—C2—C3124.97 (16)C10—C11—H11120.1
C1—C2—H2117.5C11—C12—C13117.54 (17)
C3—C2—H2117.5C11—C12—H12121.2
N2—C3—C15120.71 (15)C13—C12—H12121.2
N2—C3—C2117.31 (15)N1—C13—C12129.44 (16)
C15—C3—C2121.94 (15)N1—C13—C8107.56 (15)
N2—C4—C5112.73 (15)C12—C13—C8123.00 (16)
N2—C4—H4A109.0N1—C14—C7110.71 (16)
C5—C4—H4A109.0N1—C14—H14124.6
N2—C4—H4B109.0C7—C14—H14124.6
C5—C4—H4B109.0C3—C15—C16125.26 (16)
H4A—C4—H4B107.8C3—C15—H15117.4
C4—C5—C6110.69 (14)C16—C15—H15117.4
C4—C5—H5A109.5O1—C16—C15125.42 (16)
C6—C5—H5A109.5O1—C16—C17117.02 (15)
C4—C5—H5B109.5C15—C16—C17117.55 (15)
C6—C5—H5B109.5C16—C17—H17A109.5
H5A—C5—H5B108.1C16—C17—H17B109.5
C1—C6—C5112.85 (15)H17A—C17—H17B109.5
C1—C6—H6A109.0C16—C17—H17C109.5
C5—C6—H6A109.0H17A—C17—H17C109.5
C1—C6—H6B109.0H17B—C17—H17C109.5
C5—C6—H6B109.0N2—C18—H18A109.5
H6A—C6—H6B107.8N2—C18—H18B109.5
C14—C7—C8105.58 (15)H18A—C18—H18B109.5
C14—C7—C1125.92 (16)N2—C18—H18C109.5
C8—C7—C1128.47 (15)H18A—C18—H18C109.5
C9—C8—C13118.31 (15)H18B—C18—H18C109.5
C9—C8—C7134.56 (16)
C7—C1—C2—C3179.45 (15)C13—C8—C9—C10−1.1 (2)
C6—C1—C2—C3−3.2 (3)C7—C8—C9—C10−175.93 (18)
C18—N2—C3—C15−9.5 (2)C8—C9—C10—C11−2.6 (3)
C4—N2—C3—C15161.62 (16)C8—C9—C10—Br1174.36 (12)
C18—N2—C3—C2173.07 (15)C9—C10—C11—C123.2 (3)
C4—N2—C3—C2−15.8 (2)Br1—C10—C11—C12−173.73 (14)
C1—C2—C3—N2−38.6 (2)C10—C11—C12—C130.0 (3)
C1—C2—C3—C15144.00 (18)C14—N1—C13—C12−179.52 (18)
C3—N2—C4—C583.4 (2)C14—N1—C13—C80.26 (19)
C18—N2—C4—C5−105.10 (17)C11—C12—C13—N1176.04 (18)
N2—C4—C5—C6−44.4 (2)C11—C12—C13—C8−3.7 (3)
C2—C1—C6—C570.7 (2)C9—C8—C13—N1−175.47 (15)
C7—C1—C6—C5−111.84 (17)C7—C8—C13—N10.68 (19)
C4—C5—C6—C1−40.5 (2)C9—C8—C13—C124.3 (3)
C2—C1—C7—C14150.24 (18)C7—C8—C13—C12−179.53 (16)
C6—C1—C7—C14−27.2 (2)C13—N1—C14—C7−1.2 (2)
C2—C1—C7—C8−27.8 (3)C8—C7—C14—N11.53 (19)
C6—C1—C7—C8154.82 (17)C1—C7—C14—N1−176.84 (15)
C14—C7—C8—C9173.91 (19)N2—C3—C15—C16172.13 (16)
C1—C7—C8—C9−7.8 (3)C2—C3—C15—C16−10.5 (3)
C14—C7—C8—C13−1.33 (18)C3—C15—C16—O1−10.6 (3)
C1—C7—C8—C13176.99 (16)C3—C15—C16—C17168.01 (16)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1N···O1i0.78 (2)2.02 (2)2.7549 (19)159 (2)

Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: JJ2030).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Allen, F. H., Howard, J. A. K. & Pitchford, N. A. (1993). Acta Cryst. B49, 910–928.
  • Bishop, D. I., Al-Khawaja, I. K., Heatley, F. & Joule, J. A. (1982a). J. Chem. Res. (S), 159.
  • Bishop, D. I., Al-Khawaja, I. K., Heatley, F. & Joule, J. A. (1982b). J. Chem. Res. (M), 1766–1776.
  • Bishop, D. I., Al-Khawaja, I. K. & Joule, J. A. (1981a). J. Chem. Res. (S), 361.
  • Bishop, D. I., Al-Khawaja, I. K. & Joule, J. A. (1981b). J. Chem. Res. (M), 4279–4290.
  • Bruker (2001). SMART Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2002). SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc.97, 1354–1358.
  • Harris, M. & Joule, J. A. (1978a). J. Chem. Res. (S), 25.
  • Harris, M. & Joule, J. A. (1978b). J. Chem. Res. (M), 0470–0483.
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]

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