Synthesis of dibenzo-fused seven-membered heterocycles via copper-catalyzed cyclization of 2-haloaniline compounds

Article abstract of DOI:10.1055/s-2008-1032055

A one-step synthesis of dibenzo-fused seven-membered nitrogen heterocycles from acetophenones/benzophenones and 2-haloanilines, via a copper-catalyzed amination, was developed. The reaction involves amination followed by intramolecular cyclization. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2008-1032055

448
LETTER
Synthesis of Dibenzo-Fused Seven-Membered Heterocycles via
Copper-Catalyzed Cyclization of 2-Haloaniline Compounds
Synthesis of
D
ibenzo-F
i
use
d
S
n
e
ven-Memb
g
eredHeteroc
y
ycles u Yang, Liansheng Wu, Debing She, Haohao Hui, Qin Zhao, Min Chen, Guosheng Huang,* Yongmin Liang
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. of China
Fax +86(931)8912582; E-mail: hgs@lzu.edu.cn
Received 12 July 2007
use of PPh3 as a ligand did not improve the product yield
(entry 10). Other catalyst systems were also tested, such
as CuO, Cu(PPh3)2NO3, CuI, CuI–PPh3, Cu, and were
found to be less effective (entries 11–15).
Abstract: A one-step synthesis of dibenzo-fused seven-membered
nitrogen heterocycles from acetophenones/benzophenones and 2-
haloanilines, via a copper-catalyzed amination, was developed. The
reaction involves amination followed by intramolecular cyclization.
Key words: heterocycles, copper catalyst, arylation–cyclization, 2- Under the optimized reaction conditions, the breadth and
haloaniline
the scope of the reaction were next investigated. The reac-
tions of 1-(2-aminophenyl)ethanone (1a) with 2-iodo-
anilines having various substituents produced high yields
of the dibenzo-fused seven-membered nitrogen deriva-
tives and only a very small amount of the cross-coupling
products was isolated (Table 2, entries 1–4). However, 2-
iodoaniline 2e bearing an electron-withdrawing group
was unable to afford the desired product. Instead, only the
cross-coupling product was obtained (entry 5). Similarly,
the reactions of 2-aminobenzophenones were also stud-
ied. Moderate to good yields of the expected products
were obtained and the cross-coupling products were not
observed (entries 6–10, 12 and 13). However, when the 2-
iodoaniline 2f was used we could not get the target prod-
uct (entry 11). Presumably, the difficulty for cyclization
was due to the presence of electron-withdrawing groups.
Heterocycles are one of the most studied subjects as their
structural units are widely found in numerous natural
products.1 In particular, seven- and eight-membered ring
heterocycles constitute a number of biologically interest-
ing molecules.2 The abundance of these medium-sized
rings in pharmaceuticals and agrochemicals continues to
ensure that they are important synthetic targets for organic
chemists.
In recent years, transition-metal-catalyzed arylation of
amines has been shown to be extremely effective for ap-
plication in the field of organic synthesis.3–5 The forma-
tion of carbon–heteroatom bond via a copper-catalyzed
amination reaction has been also successfully developed
during the past few years.6 However, the use of ligands
(amino acids,7 diamines,8 and diols9), poor substrate
scope, or the need to use stoichiometric amounts of copper
reagents have limited the utility of these reactions in some
cases.10 A significant challenge in this case is combination
of amination and construction of medium-sized heterocy-
cles using copper salts in the absence of ligands. Hence,
we want to report an arylation–cyclization reaction for the
synthesis of seven-membered nitrogen heterocycles in the
presence of a ligand-free catalyst (Scheme 1).
We also attempted to extend the method to the less reac-
tive 2-bromoaniline (2g). However, a lower yield was ob-
tained and longer reaction time was required (entry 14).
The use of 2-aminobenzaldehyde (1f) gave the corre-
sponding product in 60% yield (entry 15). When methyl
2-aminobenzoate (1g) was subjected to the copper-cata-
lyzed reaction, only the amination product was isolated
(entry 16).
To clarify the effect of catalyst, we examined the reaction
of 1a and 2a in the absence of the copper catalyst. Neither
dehydration (products A, B) nor amination (product C)
was observed (Scheme 2).
Our initial study began with the reaction of 1a (1.5 equiv),
2a (1.0 equiv, 0.30 mmol), Cu2O (10 mol%) as the cata-
lyst, and K2CO3 (1.5 equiv) in toluene at 110 °C under ar-
gon for 12 hours. The desired product 3a was isolated in a
45% yield (Table 1, entry 1). The effect of the base on the
coupling–cyclization reaction was examined. In general,
the use of K2CO3 gave yields superior to those achieved
with Cs2CO3, K3PO4 or Et3N (entries 2–4). Further opti-
mization of the reaction conditions revealed that the use of
xylene was more effective than toluene, dimethyl sulfox-
ide (DMSO), N,N-dimethylformamide (DMF), benzene
or N-methyl-2-pyrrolidinone (NMP) (entries 5–9). The
In summary, we have developed a novel methodology for
the synthesis of dibenzo-fused seven-membered nitrogen
heterocycles, based on the N-arylation of 2-haloaniline,
followed by intramolecular cyclization in the presence of
a common and cheap catalyst. This is an efficient strategy
for the synthesis of a variety of dibenzo-fused seven-
membered heterocycles.
SYNLETT 2008, No. 3, pp 0448–0452
x
x.
x
x.
2
0
0
8
Advanced online publication: 16.01.2008
DOI: 10.1055/s-2008-1032055; Art ID: W13307ST
© Georg Thieme Verlag Stuttgart · New York

LETTER
Synthesis of Dibenzo-Fused Seven-Membered Heterocycles
449
O
R1
O
N
R1
[Cu]
catalyst
R1
H2N
X
R3
R3
+
R2
R2
R3
+
R2
base,
solvent
NH2
N
N
H
H
H2N
4a
1a
2a
3a
Scheme 1
O
N
N
+
NH2
NH2
O
I
H2N
A
B
+
NH2
I
NH2
NH
1a
2a
O
C
Scheme 2
Table 1 Optimization of the Copper-Catalyzed Cyclization of 1a with 2-Iodoaniline 2aa
Entry
1
Catalyst
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O
Cu2O–PPh3
CuO
Base
Solvent
toluene
toluene
xylene
toluene
DMSO
DMF
Temp (°C)
110
Time (h)
Yieldb (%) of 3a Yieldb (%) of 4a
K2CO3
Cs2CO
K3PO4
Et3N
12
12
8
45
–
–
15
–
–
–
–
–
6
6
7
6
–
–
9
2
110
38
3
145
48
4
110
12
12
12
8
31
5
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
110
trace
10
6
110
c
7
benzene
NMP
145
–
8
110
12
8
trace
88
9
xylene
xylene
xylene
xylene
xylene
xylene
xylene
145
10
11
12
13
14
15
145
8
84
145
8
75
[Cu]d
145
8
76
c
CuI
145
8
–
c
CuI–PPh3
Cu
145
8
–
145
8
83
a Reactions were carried out on a 0.3-mmol scale in solvent (1.0 mL) under argon for the specified period of time with 1a (1.5 equiv), 2a (1.0
equiv), base (1.5 equiv), and catalyst (0.10 equiv).
b Isolated yields.
c No reaction.
d [Cu] = Cu(PPh3)2NO3.
Synlett 2008, No. 3, 448–452 © Thieme Stuttgart · New York

450
M. Yang et al.
LETTER
Table 2 Synthesis of Dibenzo-Fused Seven-Membered Nitrogen Heterocyclesa,11
Entry Ketone
Aniline
Product
Time Yieldb (%) Yieldb (%)
(h)
of 3
of 4
O
N
N
N
N
H2N
1
2
3
4
1a
1a
1a
1a
2a
2b
2c
2d
3a
8
88
5
I
N
H
NH2
I
3b
3c
3d
8
90
5
6
7
NH2
N
H
H2N
I
4.5 85
Cl
Cl
N
H
H2N
I
6
75
–
Br
Br
N
H
NO2
I
H2N
5
1a
2e
2a
4e
12
85
NH2
N
H
NO2
O
Ph
O
N
N
N
6
7
8
9
1b
1b
1b
1c
3f
5
5
7
8
80
76
80
80
–
N
NH2
H
Ph
Ph
Ph
Ph
2b
2c
2a
2b
3g
3h
–
–
–
–
N
H
Cl
N
H
O
N
Cl
Cl
3i
3j
N
H
NH2
N
O
Cl
Cl
10 1c
2.5 78
N
H
Ph
H2N
I
NH2
11 1c
2f
4k
20
–
75
N
H
NO2
NO2
Synlett 2008, No. 3, 448–452 © Thieme Stuttgart · New York

LETTER
Synthesis of Dibenzo-Fused Seven-Membered Heterocycles
451
Table 2 Synthesis of Dibenzo-Fused Seven-Membered Nitrogen Heterocyclesa,11 (continued)
Entry Ketone
Aniline
Product
Time Yieldb (%) Yieldb (%)
(h)
of 3
of 4
4-Tol
4-Tol
O
N
Cl
Cl
12 1d
2a
3l
6
82
–
NH2
N
H
N
N
Cl
Cl
13 1d
2d
3m
13
68
–
Br
N
H
Ph
Br
14 1d
2g
2a
3n
3o
20
7
40
60
–
9
NH2
N
H
O
N
15 1f
H
N
H
NH2
O
O
OMe
H2N
16 1g
2a
4p
8
–
70
OMe
NH2
N
H
a All reactions were carried out under the optimal conditions reported in the text.
b Isolated yields.
Chem. 1990, 33, 1246. (g) Boegesoe, K. P.; Arnt, J.; Boeck,
V.; Christensen, A. V.; Hyttel, J.; Jensen, K. G. J. Med.
Chem. 1988, 31, 2247. (h) Hodge, C. N.; Pierce, J. Bioorg.
Med. Chem. Lett. 1993, 3, 1605.
Acknowledgment
The authors thank the State Key Laboratory of Applied Organic
Chemistry for financial support.
(3) Hartwig, J. F. Modern Arene Chemistry; Astruc, D., Ed.;
Wiley-VCH: Weinheim, 2002, Chap. 4.
(4) Schlummer, B.; Scholz, U. Adv. Synth. Catal. 2004, 346,
1599.
References and Notes
(1) (a) Cutignano, A.; Tramice, A.; De Caro, S.; Villani, G.;
Cimino, G.; Fontana, A. Angew. Chem. Int. Ed. 2003, 42,
2633. (b) Renneberg, D.; Dervan, P. B. J. Am. Chem. Soc.
2003, 125, 5707. (c) Occhiato, E. G.; Prandi, C.; Ferrali, A.;
Guarna, A.; Venturello, P. J. Org. Chem. 2003, 68, 9728.
(d) Deng, J.; Zhao, S.; Miao, Z. Nat. Prod. Lett. 1993, 2,
283. (e) Evans, P. A.; Holmes, A. B. Tetrahedron 1991, 47,
9131. (f) Joule, J. A.; Mills, K. Heterocyclic Chemistry, 4th
ed.; Blackwell: Oxford, 2000.
(2) (a) Geronikaki, A. A.; Dearden, J. C.; Filimonov, D.;
Galaeva, I.; Garibova, T. L.; Gloriozova, T.; Krajneva, V.;
Lagunin, A.; Macaev, F. Z.; Molodavkin, G.; Poroikov, V.
V.; Pogrebnoi, S. I.; Shepeli, F.; Voronina, T. A.;
(5) Tsuji, J.; Mandai, T. Synthesis 1996, 1.
(6) For reviews, see: (a) Kunz, K.; Scholz, U.; Ganzer, D.
Synlett 2003, 2428. (b) Ley, S. V.; Thomas, A. W. Angew.
Chem. Int. Ed. 2003, 42, 5400. (c) Dehli, J. R.; Legros, J.;
Bolm, C. Chem. Commun. 2005, 973.
(7) (a) Ma, D.; Xia, C.; Jiang, J.; Zhang, J.; Tang, W. J. Org.
Chem. 2003, 68, 442. (b) Ma, D.; Cai, Q.; Zhang, H. Org.
Lett. 2003, 5, 2453. (c) Ma, D.; Xia, C. Org. Lett. 2001, 3,
2583. (d) Clement, J.-B.; Hayes, J. F.; Sheldrake, H. M.;
Sheldrake, P. W.; Wells, A. S. Synlett 2001, 1423. (e) Ma,
D.; Zhang, Y.; Wu, S.; Tao, F. J. Am. Chem. Soc. 1998, 120,
12459.
(8) (a) Wang, X.; Porco, J. A. Jr. J. Am. Chem. Soc. 2003, 125,
6040. (b) Padwa, A.; Crawford, K. R.; Rashatasakhon, P.;
Rose, M. J. Org. Chem. 2003, 68, 2609. (c) Fredrick, M.
O.; Mulder, J. A.; Tracey, M. R.; Hsung, R. P.; Huang, J.;
Kurtz, K. C. M.; Shen, L.; Douglas, C. J. J. Am. Chem. Soc.
2003, 125, 2368. (d) Klapars, A.; Buchwald, S. L. J. Am.
Chem. Soc. 2002, 124, 14844. (e) Antilla, J. C.; Klapars, A.;
Buchwald, S. L. J. Am. Chem. Soc. 2002, 124, 11684.
(f) Klapars, A.; Huang, X.; Buchwald, S. L. J. Am. Chem.
Soc. 2002, 124, 7421. (g) Wolter, M.; Klapars, A.;
Tsitlakidou, M.; Vlad, L. J. Med. Chem. 2004, 47, 2870.
(b) Dutton, F. E.; Lee, B. H.; Johnson, S. S.; Coscarelli, E.
M.; Lee, P. H. J. Med. Chem. 2003, 46, 2057.
(c) Weintraub, P. M.; Sabol, J. S.; Kane, J. M.; Borcherding,
D. R. Tetrahedron 2003, 59, 2953. (d) Yoshida, H.;
Shirakawa, E.; Honda, Y.; Hiyama, T. Angew. Chem. Int.
Ed. 2002, 41, 3247. (e) Bujard, M.; Gouverneur, V.;
Mioskowski, C. J. Org. Chem. 1999, 64, 2119. (f) Cooper,
C. S.; Klock, P. L.; Chu, D. T. W.; Fernandes, P. B. J. Med.
Synlett 2008, No. 3, 448–452 © Thieme Stuttgart · New York

452
M. Yang et al.
LETTER
Buchwald, S. L. Org. Lett. 2001, 3, 3803. (h) Klapars, A.;
Antilla, J. C.; Huang, X.; Buchwald, S. L. J. Am. Chem. Soc.
2001, 123, 7727.
a yellow solid. 1H NMR (300 MHz, CDCl3): d = 2.13 (s, 6
H), 2.17 (s, 3 H), 4.81 (s, 1 H), 6.45 (s, 1 H), 6.61–6.64 (d,
J = 7.5 Hz, 1 H), 6.78 (s, 1 H), 7.02–7.09 (m, 1 H), 7.22 (s,
1 H), 7.36–7.41 (m, 3 H), 7.70–7.74 (m, 2 H). 13C NMR (75
MHz, CDCl3): d = 18.8, 19.0, 20.4, 119.4, 120.8, 127.2,
127.9, 129.5, 129.6, 131.6, 131.9, 132.1, 132.4, 135.2,
138.4, 140.2, 141.5, 152.0, 168.7. IR (KBr): 695, 731, 1464,
1613, 2920, 3329 cm–1. EI–MS: m/z = 312 [M+], 297. Anal.
Calcd for C22H20N2: C, 84.58; H, 6.45; N, 8.97. Found: C,
84.59; H, 6.53; N, 8.89.
(9) (a) Buchwald, S. L.; Klapars, A.; Antilla, J. C.; Job, G. E.;
Wolter, M.; Kwong, F. Y.; Nordmann, G.; Hennessy, E. J.
Int. Patent, WO02085838 A1, 2002. (b) Kwong, F. Y.;
Klapars, A.; Buchwald, S. L. Org. Lett. 2002, 4, 581.
(10) (a) Ullmann, F. Ber. Dtsch. Chem. Ges. 1903, 36, 2382.
(b) For a review, see: Lindley, J. Tetrahedron 1984, 40,
1433.
(11) Typical Procedure for the Preparation of Dibenzo-Fused
Seven-Membered Nitrogen Heterocycles Compounds: A
mixture of 1a (60.8 mg, 0.45 mmol), 2b (69.9 mg, 0.3
mmol), Cu2O (4.3 mg, 0.03 mmol) and K2CO3 (62.1 mg,
0.45mmol) was placed in xylene (1.0 mL) under Ar at 145
°C in a round-bottomed flask. When the reaction was
considered complete as determined by TLC analysis, the
reaction mixture was allowed to cool to r.t., and the mixture
was extracted with EtOAc. The combined organic extracts
were washed with H2O and sat. brine. The organic layers
were dried over MgSO4, and filtered. Solvents were
evaporated under reduced pressure. The residue was purified
by chromatography on silica gel (hexanes–EtOAc, 10:1) to
afford 7,11-dimethyl-5H-dibenzo[b,e][1,4]diazepine (3a;
53.9 mg, 88%) as a yellow solid; mp 133–135 °C. 1H NMR
(300 MHz, CDCl3): d = 2.23 (s, 3 H), 2.54 (s, 3 H), 4.86 (s,
1 H), 6.48 (s, 1 H), 6.65–6.68 (d, J = 8.4 Hz, 1 H), 6.80–6.83
(d, J = 7.5 Hz, 1 H), 6.94–6.99 (m, 1 H), 7.03–7.05 (d, J =
6.0 Hz, 1 H), 7.19–7.31 (m, 2 H). 13C NMR (75 MHz,
CDCl3): d = 20.6, 28.4, 119.2, 120.2, 122.8, 124.8, 127.9,
129.0, 129.3, 131.6, 136.6, 138.1, 142.2, 153.0, 168.9. IR
(KBr): 761, 1281, 1459, 1630, 3278, 3348 cm–1. EI–MS:
m/z = 222 [M+], 207, 192, 111 cm–1. Anal. Calcd for
C15H14N2: C, 81.05; H, 6.35; N, 12.60. Found: C, 80.87; H,
6.09; N, 12.71.
2-Chloro-7-methyl-11-phenyl-5H-dibenzo[b,e][1,4]di-
azepine (3i): The reaction mixture was chromatographed
using hexanes–EtOAc (50:1) to afford 3i (71.7 mg, 80%) as
an orange solid. 1H NMR (300 MHz, CDCl3): d = 2.25 (s, 3
H), 4.90 (s, 1 H), 6.49 ( s, 1 H), 6.67–6.70 (d, J = 8.1 Hz, 1
H), 6.86–6.89 (d, J = 8.1 Hz, 1 H), 6.96–6.97 (m, 1 H), 7.18–
7.25 (m, 2 H), 7.38–7.45 (m, 3 H), 7.68–7.71 (m, 2 H). 13
NMR (75 MHz, CDCl3): d = 20.7, 120.4, 121.0, 125.2,
127.7, 128.1, 128.7, 128.9, 129.4, 130.1, 131.4, 131.6,
137.3, 138.1, 140.8, 141.7, 152.8, 167.1. IR (KBr): 1450,
C
1615, 3269, 3348 cm–1. EI–MS: m/z = 318 [M+], 283, 268,
214. Anal. Calcd for C20H15ClN2: C, 75.35; H, 4.74; N, 8.79.
Found: C, 75.43; H, 4.87; N, 8.98.
2-Chloro-7,8-dimethyl-11-phenyl-5H-
dibenzo[b,e][1,4]diazepine (3j): The reaction mixture was
chromatographed using hexanes–EtOAc (50:1) to afford 3j
(72.8 mg, 78%) as a yellow solid. 1H NMR (300 MHz,
CDCl3): d = 2.11–2.24 (m, 6 H), 4.87 (s, 1 H), 6.43 (s, 1 H),
6.64–6.66 (m, 1 H), 6.95–6.96 (m, 1 H), 7.09 (s, 1 H), 7.15–
7.23 (m, 1 H), 7.37–7.46 (m, 3 H), 7.68–7.71 (m, 2 H). 13
C
NMR (75 MHz, CDCl3): d = 18.8, 19.1, 120.9, 120.9, 127.6,
128.1, 128.8, 129.3, 129.6, 130.0, 131.4, 131.5, 132.5,
135.7, 138.2, 139.4, 140.8, 153.1, 167.1. IR (KBr): 696, 731,
1462, 1617, 2920, 3341 cm–1. EI–MS: m/z = 332 [M+], 297,
214, 111. Anal. Calcd for C21H17ClN2: C, 75.78; H, 5.15; N,
8.42. Found: C, 75.67; H, 5.05; N, 8.48.
7-Bromo-2-chloro-11-m-tolyl-5H-dibenzo[b,e][1,4]di-
azepine (3m): The reaction mixture was chromatographed
using hexanes–EtOAc (50:1) to afford 3m (75.1 mg, 68%) as
a yellow solid. 1H NMR (300 MHz, CDCl3): d = 3.26 (s, 3
H), 4.94 (s, 1 H), 6.71–6.73 (d, J = 8.1 Hz, 1 H), 6.87 (s, 1
H), 6.99–7.00 (m, 1 H), 7.14–7.18 (m, 2 H), 7.24–7.30 (m, 3
H), 7.38 (s, 1 H), 7.56 (s, 1 H). 13C NMR (75 MHz, DMSO-
d6): d = 21.7, 120.1, 122.7, 123.3, 126.8, 127.0, 127.1, 128.8,
129.2, 130.1, 130.5, 131.3, 131.9, 132.8, 138.2, 140.3,
140.7, 145.7, 154.8, 168.7. IR (KBr): 628, 764, 825, 1026,
1652, 2253, 3414 cm–1. EI–MS: m/z = 396 [M+], 361. Anal.
Calcd for C20H14BrClN2: C, 60.40; H, 3.55; N, 7.04. Found:
C, 60.55; H, 3.36; N, 7.18.
7-Methyl-5H-dibenzo[b,e][1,4]diazepine (3o): The
reaction mixture was chromatographed using hexanes–
EtOAc (10:1) to afford 3o (34.3 mg, 60%) as a dark red
solid. 1H NMR (300 MHz, CDCl3): d = 2.20 (s, 3 H), 4.84 (s,
1 H), 6.30 (s, 1 H), 6.44–6.47 (d, J = 7.5 Hz, 1 H), 6.72–6.74
(d, J = 7.5 Hz, 2 H), 6.83–6.88 (t, J = 7.5 Hz, 1 H), 6.99–7.04
(t, J = 7.5 Hz, 2 H), 7.11–7.16 (t, J = 14.7 Hz, 1 H), 8.04 (s,
1 H). 13C NMR (75 MHz, CDCl3): d = 20.6, 118.3, 120.5,
122.4, 124.6, 126.3, 130.5, 131.9, 132.6, 137.6, 138.7,
142.3, 151.8, 162.1. IR (KBr): 746, 1456, 1588, 2920, 3355
cm–1. EI–MS: m/z = 208 [M+]. Anal. Calcd for C14H12N2: C,
80.74; H, 5.81; N, 13.45. Found: C, 80.64; H, 5.67; N, 13.53.
7-Chloro-11-methyl-5H-dibenzo[b,e][1,4]diazepine (3c):
The reaction mixture was chromatographed using hexanes–
EtOAc (10:1) to afford 3c (58.2 mg, 85%) as a brown solid.
1H NMR (300 MHz, CDCl3): d = 2.52–2.53 (m, 3 H), 4.89
(s, 1 H), 6.65–6.68 (d, J = 7.5 Hz, 2 H), 6.95–7.06 (m, 3 H),
7.22–7.32 (m, 2 H). 13C NMR (75 MHz, CDCl3): d = 28.5,
119.5, 119.6, 123.3, 124.1, 129.0, 129.4, 131.8, 131.9,
134.8, 139.2, 143.4, 152.3, 170.1. IR (KBr): 758, 1456,
1631, 3272, 3356 cm–1. EI–MS: m/z = 242 [M+], 207. Anal.
Calcd for C14H11ClN2: C, 69.28; H, 4.57; N, 11.54. Found:
C, 69.37; H, 4.38; N, 11.45.
1-[2-(2-Amino-5-methyl-3-nitrophenylamino)phen-
yl]ethanone (4e): The reaction mixture was
chromatographed using hexanes–EtOAc (30:1) to afford 4e
(68.4 mg, 85%) as an orange solid. 1H NMR (300 MHz,
CDCl3): d = 2.26 (s, 3 H), 2.67 (s, 3 H), 6.26 (s, 2 H), 6.55–
6.58 (d, J = 8.7 Hz, 1 H), 6.76–6.82 (t, J = 7.2 Hz, 1 H), 7.23–
7.34 (m, 2 H), 7.84–7.90 (t, J = 7.5 Hz, 2 H), 10.03 (s, 1 H).
13C NMR (75 MHz, CDCl3): d = 20.1, 28.0, 114.2, 117.2,
119.0, 123.7, 125.2, 128.4, 132.4, 132.6, 135.1, 135.5,
140.6, 148.8, 201.8. IR (KBr): 750, 1225, 1450, 1576, 1638,
3373, 3472 cm–1. EI–MS: m/z = 285 [M+], 195, 120. Anal.
Calcd for C15H15N3O3: C, 63.15; H, 5.30; N, 14.73. Found:
C, 63.31; H, 5.10; N, 14.87.
2,7,8-Trimethyl-11-phenyl-5H-dibenzo[b,e][1,4]di-
azepine (3g): The reaction mixture was chromatographed
using hexanes–EtOAc (50:1) to afford 3g (66.5 mg, 76%) as
Synlett 2008, No. 3, 448–452 © Thieme Stuttgart · New York

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