In recent works, Palma et al. [6, 7] have described an expedient synthetic route to construct a tetrahydro-1-
benzazepine skeleton from readily available N-allyl-N-benzylanilines, through the aromatic amino-Claisen rearrangement
and the intramolecular 1,3-dipolar cycloaddition as main transformations, and also applied the above synthetic route to the
stereoselective synthesis and crystal structure analyses of different derivatives [8-10]. Compounds of this type show
a promising action against Trypanosoma cruzi and Leishmania chagasi parasites [10].
The present work reports the crystal structure of 11-ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine synthesized by the
BF –Et O catalyzed aromatic amino-Claisen rearrangement and the intramolecular alkene Friedel–Crafts alkylation [6].
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2
EXPERIMENTAL
3 2
Synthesis. 11-Ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine (I) was synthesized by the BF –Et O catalyzed aromatic
amino-Claisen rearrangement and the intramolecular alkene Friedel–Crafts alkylation (Scheme 2) explained elsewhere [6].
Reagents and conditions are: NaBH , MeOH (a), BrCH CH=CH , DMF, K CO , reflux (b), BF ⋅OEt , 140-155 °C (c),
2 2 3 3 2
4
2
H
2 4
SO , 80-90 °C (d). X-ray quality crystals suitable for the X-ray diffraction analysis were obtained from a chloroform
solution after slow evaporation.
Scheme 2. Synthesis of 11-ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine I.
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NMR spectroscopic studies. H NMR and C NMR spectra were recorded on a Bruker Avance 400 model
1
6 3
spectrometer in the DMSO-d solution. H NMR (400 MHz, CDCl , ppm): δ = 0.91 (3H, t, J = 7.4 Hz, H13), 2.17 (2H, m,
H12), 3.69 (1H, t, J = 7.3 Hz, H11), 4.00 (1H, d, J = 14.8 Hz, H6b), 4.95 (1H, d, J = 14.8 Hz, H6a), 6.50 (1H, d, J = 8.0 Hz,
H4), 6.67 (1H, td, J = 8.0, 1,0 Hz, H2), 6.96 (1H, td, J = 8.0, 1.0 Hz, H3), 7.12 (1H, dd, J = 8.0, 1.0 Hz, H1), 7.19-7.30 (4H,
13
m, H7–H10). C NMR (100 MHz, CDCl , ppm): δ = 13.0 (C13), 31.6 (C12), 51.1 (C6), 54.8 (C11) 117.9 (C4), 118.2 (C2),
3
127.2 (C3), 127.6-129.5 (C7–C10), 130.2 (C11a), 130.8 (C1), 136.5 (C6a), 142.1 (C10a), 146.2 (C4a).
X-ray data collection and structure determination. A colorless rectangular crystal (0.5×0.3×0.2 mm) was used
for data collection. Diffraction data were collected at 298(2) K by the ω-scan technique on a Rigaku AFC7S Mercury
diffractometer [11] with graphite-monochromatized MoK radiation (λ = 0.71073 Å). The data were corrected for Lorentz
α
polarization and absorption effects. The structure was solved by direct methods using the SHELXS program [12] and refined
2
by a full-matrix least-squares calculation on F using SHELXL [13]. All H atoms were placed at the calculated positions and
treated using the riding model, with C–H distances of 0.97-0.98 Å, and N–H distances of 0.86 Å. The Uiso (H) parameters
were fixed at 1.2Ueq (C, N) and 1.5Ueq (methyl groups). All geometrical calculations were made using the Platon program
[14]. Table 1 summarizes the crystal data, intensity data collection, and refinement details for I. CIF file containing complete
information on the studied structure was deposited with CCDC, deposition number 995653, and is freely available upon
request from the following web site: www.ccdc.cam.ac.uk/data_request/cif.
RESULTS AND DISCUSSION
1
Title compound I C16H17N crystallizes in the monoclinic space group P2 /n. The crystal packing efficiency reaches
66.4%. Fig. 1 shows the molecular structure and the atom labeling scheme of 11-ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine.
Selected geometrical parameters are presented in Table 2. All bond distances and angles are normal [15] and are in agreement
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