Facile synthesis of coumarin- and quinolone-annulated benzazoninone derivatives by an intramolecular heck reaction strategy via 9- exo -trig cyclization

Article abstract of DOI:10.1055/s-0030-1260005

A synthetic strategy based on the application of the aromatic aza-Claisen rearrangement followed by an intramolecular Heck reaction sequence as the key step has been developed for the regiocontrolled synthesis of hitherto unreported coumarin- and quinolon

Full text of DOI:10.1055/s-0030-1260005

PAPER
1569
Facile Synthesis of Coumarin- and Quinolone-Annulated Benzazoninone
Derivatives by an Intramolecular Heck Reaction Strategy via 9-exo-trig
Cyclization
S
ynthesis of Coum
.
arin- and Q
u
C
inolone-Annulat
.
ed
B
enzazon
M
inone
D
erivatives ajumdar,* Tapas Ghosh, Srikanta Samanta
Department of Chemistry, University of Kalyani, Kalyani 741235, India
Fax +91(3712)267005; E-mail: kcm_ku@yahoo.co.in
Received 20 January 2011; revised 14 March 2011
mode, as this is by far less sterically demanding.9 We have
earlier reported the synthesis of eight-membered10 aza-
heterocycles (azocines) and nine-membered11 oxa-hetero-
cycles by the palladium(0)-catalyzed intramolecular Heck
reaction;12 however, there are no such reports on the syn-
thesis of coumarin- and quinolone-annulated benzazoni-
nones starting from unactivated allylic substrates. As a
part of our ongoing studies toward the synthesis of medi-
um-ring heterocycles,13 we became interested in synthe-
sizing coumarin- and quinolone-annulated azoninone
derivatives (nine-membered lactams) by the implementa-
tion of the aza-Claisen rearrangement and the Heck car-
bon–carbon coupling reaction.
Abstract: A synthetic strategy based on the application of the aro-
matic aza-Claisen rearrangement followed by an intramolecular
Heck reaction sequence as the key step has been developed for the
regiocontrolled synthesis of hitherto unreported coumarin- and
quinolone-annulated benzazoninone derivatives in 48–69% yield.
Key words: coumarin, quinolone, benzazoninones, aza-Claisen re-
arrangement, Heck reaction
The synthesis of nine-membered nitrogen-containing het-
erocycles (‘azoninones’) in a regioselective manner has
been, and continues to be, a challenging task in the field
of synthetic organic chemistry. Azoninones are found as
subunits in natural and pharmaceutically important prod-
ucts.1 Medium-sized rings in general are quite important
in medicinal chemistry due to their structural divergency
and are the structural cores of a number of biologically ac-
tive natural products; they also serve as target molecules.2
On the other hand, the medium-sized constrained nitro-
gen-containing ring systems can serve as key intermedi-
ates in the synthesis of bicyclic amino compounds by
selective transannular ring contractions.3 The scope of
conventional cyclization strategies to medium-sized rings
is limited by unfavorable entropy factors, enthalpy fac-
tors, transannular interactions and the lack of functional
diversity of the reaction products.4 Constrained azonines
bearing an E-configured double bond have been efficient-
ly constructed by the zwitterionic aza-Claisen rearrange-
Compounds 1a–d and 3a,b were prepared utilizing the ar-
omatic aza-Claisen rearrangement according to the pub-
lished procedures.14 Compound 1a was reacted with (2-
iodophenyl)acetyl chloride in the presence of potassium
carbonate and tetrabutylammonium hydrogen sulfate
(TBAHS) as a phase-transfer catalyst in dichlo-
romethane–water at room temperature for 14 hours to give
the Heck precursor 2a (Scheme 1). The other precursors,
2b–d and 4a,b, were prepared similarly.
NHR
O
X
I
ment, developed by Edstrom from a ketene-Claisen
reaction, for the formation of nine- and ten-membered-
ring lactams.5 Although there are some elegant examples
of the stereochemically controlled construction of nine-
membered nitrogen heterocycles via ring expansion, this
is still a less studied area in organic synthesis.6
R
1a–d
N
i
+
O
O
X
ClOC
I
2a, X = O, R = Me; 87%
2b, X = O, R = Et; 85%
2c, X = NMe, R = Me; 85%
2d, X = NMe, R = Et; 86%
Recently, palladium catalysts have emerged as extremely
powerful tools for the formation of carbon–carbon and
carbon–heteroatom bonds.7 These catalysts are employed
in the synthesis of considerably complex molecules,8 due
to their ability to tolerate different functional groups.
ClOC
I
NHR
I
i
R
N
+
In the intramolecular Heck reaction, entropy factors dom-
inate and often control the mode of cyclization. In most of
the studied cases, the reactions proceed in the exo-trig
O
3a,b
4a, R = Me; 84%
4b, R = Et; 86%
SYNTHESIS 2011, No. 10, pp 1569–1574
Advanced online publication: 15.04.2011
DOI: 10.1055/s-0030-1260005; Art ID: Z13211SS
x
x.
x
x
.
2
0
1
1
Scheme 1 Reagents and conditions: (i) K2CO3, TBAHS (cat.),
CH2Cl2, H2O, r.t., 14 h.
© Georg Thieme Verlag Stuttgart · New York

1570
K. C. Majumdar et al.
PAPER
compound 5a, containing the nine-membered azoninone
ring, in 60% yield (Scheme 2).
I
Me
N
The formation of the tetracyclic compound 6a, containing
the ten-membered azecinone ring, was not observed. To
optimize the reaction conditions, a series of experiments
was carried out with changes in the temperature, solvent,
base and catalyst. The results are summarized in Table 1.
O
O
O
2a
i
Among the various bases used, potassium acetate was
found to be the best choice; sodium acetate, potassium
carbonate and silver carbonate gave lower yields of the
product (cf. entries 5, 7, 8 and 10). Among the various sol-
vents (DMA, MeCN, THF, dioxane), N,N-dimethylform-
amide was found to be suitable. The reaction did not occur
with palladium(II) chloride as a catalyst (entry 13). Tem-
perature has a pronounced effect on the reaction; at higher
temperature (120 °C, entry 4) decomposition occurred,
and at a slightly lower temperature the yield was also not
satisfactory (entry 6). Increasing the reaction time also re-
sulted in a decreased yield of the product. Thus, the opti-
mized reaction conditions (entry 5) are: Pd(PPh3)4 (10
mol%), TBAB (1.2 equiv), KOAc (2.5 equiv), DMF,
90 °C, 30 min. The other substrates 2b–d and 4a,b were
similarly treated under the optimized reaction conditions
and the product benzazoninones 5b–d and 7a,b were ob-
tained in moderate to good yields. The results are summa-
rized in Table 2.
O
O
N
NMe
Me
O
O
O
O
6a
5a, 60%
expected (not observed)
expected (observed)
Scheme 2 Reagents and conditions: (i) Pd(PPh3)4 (10 mol%),
TBAB (1.2 equiv), KOAc (2.5 equiv), DMF, 100 °C, 30 min.
Table 1 Optimization of the Reaction Conditionsa
Entry Catalyst
Solvent Base
Temp Time Yieldb
(°C)
100
100
100
120
90
(min) (%)
According to the literature,15 large-ring (~20) formation
with a flexible tether generally follows the endo mode of
cyclization and small- to medium-sized-ring formation
1
2
3
4
5d
6
7
8
9
Pd(OAc)2
Pd(OAc)2
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
PdCl2
DMA
DMF
DMF
DMF
DMF
DMF
DMF
DMF
THF
KOAc
45
45
30
30
30
30
30
30
15
25
60
KOAc
KOAc
KOAc
KOAc
KOAc
K2CO3
Ag2CO3
KOAc
NaOAc
KOAc
c
–
69
25
26
30
40
41
15
10
O
70
N
I
R
N
R
90
O
X
5
O
90
reductive
elimination
O
X
2
reflux 30
90 30
LnPd(0) catalyst
10
DMF
MeCN
Pd(0)
11
12
13
reflux 30
reflux 30
dioxane KOAc
DMF KOAc
I
90
30
0e
Pd
Pd
X
R
N
a TBAB (1.2 equiv) was added in all reactions.
b Isolated yield.
O
N
O
c Decomposition.
O
X
R
d Optimized reaction conditions.
e No reaction.
O
I
alkene
insertion
migratory
insertion
Pd
The intramolecular Heck reaction of the precursor 2a was
carried out in anhydrous N,N-dimethylformamide using
potassium acetate as a base, tetrabutylammonium bro-
mide as a promoter and tetrakis(triphenylphosphine)palla-
dium(0) as a catalyst under nitrogen atmosphere at 100 °C
for about 30 minutes. The reaction afforded the tetracyclic
R
N
– HI
9-exo-trig
O
O
X
X = O, NMe
R = Me, Et
Scheme 3 Regiocontrolled synthesis of the benzazoninones
Synthesis 2011, No. 10, 1569–1574 © Thieme Stuttgart · New York

PAPER
Synthesis of Coumarin- and Quinolone-Annulated Benzazoninone Derivatives
1571
Table 2 Synthesis of the Benzazoninone Derivatives
Entry
Substrate
Time (min) Product
Yield (%)
I
I
I
Me
N
1
2a
30
35
5a
69
67
O
O
O
O
NMe
O
O
O
O
O
O
Et
N
2
3
2b
5b
O
NEt
O
O
O
Me
N
2c
37
5c
61
O
NMe
N
Me
O
N
Me
I
Et
N
4
5
6
2d
4a
4b
35
40
45
5d
7a
7b
63
49
48
O
O
NEt
O
N
Me
O
N
Me
I
Me
N
O
O
NMe
I
Et
N
O
O
NEt
usually occurs via the exo mode12b,16 of cyclization. More- Nubbemeyer and co-workers6c,19 reported the synthesis of
over, medium-ring formation may be possible through 2-azoninones containing a 5,6-E double bond as interme-
endo cyclization of the double bond if connected with a diates for the preparation of biologically important in-
Michael type of olefinic fragment.17 In the present study, dolizidinone derivatives. Jung and co-workers4 described
we have obtained the exo-product exclusively the preparation of N-acyl-2-vinylpyrrolidines and their
(Scheme 3).
amide enolate induced ring expansion into functionally
divergent nine-membered unsaturated lactams which
could be key building blocks for indolizidine alkaloids.
Our methodology utilizes Heck cyclization which affords
coumarin- and quinolone-fused highly substituted benza-
zoninone derivatives in reasonably good yields using mild
Despite the widespread applicability1–3 of azoninone de-
rivatives, to our knowledge, very few methodologies are
available18 in the literature which directly afford highly
substituted azoninones as a target product and with a sat-
isfactory reaction yield.
Synthesis 2011, No. 10, 1569–1574 © Thieme Stuttgart · New York

1572
K. C. Majumdar et al.
PAPER
N-(5-Allyl-2-oxo-2H-chromen-6-yl)-N-ethyl-2-(2-iodophe-
nyl)acetamide (2b)
Yield: 722 mg (85%); gummy.
reaction conditions. To our knowledge, this is the first re-
port of the synthesis of azoninone derivatives by the Heck
reaction.
IR (KBr): 1590, 1648, 1730, 2930 cm–1.
In conclusion, we have developed an easy and efficient
protocol for the synthesis of hitherto unreported, highly
substituted coumarin- and quinolone-annulated benza-
zoninones by aza-Claisen rearrangement followed by the
intramolecular Heck reaction. As both coumarin and
azoninone moieties are known to be of biological rele-
vance, the synthesized compounds may be of biological
significance. The exocyclic methylene group present in
the synthesized azoninone derivatives offers scope for
further functionalization and, therefore, may be used for
diversity-oriented synthesis of new bioactive heterocy-
cles.
1H NMR (400 MHz, CDCl3): d = 1.16 (t, J = 7.2 Hz, 3 H), 3.08–
3.16 (m, 1 H), 3.38 (d, J = 16.0 Hz, 1 H), 3.48 (d, J = 16.0 Hz, 1 H),
3.53 (d, J = 5.6 Hz, 1 H), 3.64 (td, J = 16.8, 3.6 Hz, 1 H), 4.23–4.32
(m, 1 H), 4.89 (d, J = 17.2 Hz, 1 H), 5.18 (d, J = 10.4 Hz, 1 H),
5.91–6.01 (m, 1 H), 6.48 (d, J = 10.0 Hz, 1 H), 6.89–6.93 (m, 1 H),
7.24–7.38 (m, 4 H), 7.74 (d, J = 8.0 Hz, 1 H), 7.87 (d, J = 9.6 Hz, 1
H).
MS: m/z = 474.17 [M + H]+.
Anal. Calcd for C22H20INO3: C, 55.83; H, 4.26; N, 2.96. Found: C,
56.02; H, 4.24; N, 2.97.
N-(5-Allyl-1-methyl-2-oxo-1,2-dihydroquinolin-6-yl)-2-(2-io-
dophenyl)-N-methylacetamide (2c)
Yield: 723 mg (85%); solid; mp 142–143 °C.
IR (KBr): 1613, 1644, 1659, 2930 cm–1.
Melting points were determined in open capillaries and are uncor-
rected. IR spectra were run for KBr disks (and neat for liquid sam-
1
ples) on a Perkin-Elmer 120-000A apparatus (nmax in cm–1). H
1H NMR (400 MHz, CDCl3): d = 3.25 (s, 3 H), 3.42 (d, J = 16.0 Hz,
1 H), 3.52 (d, J = 16.0 Hz, 1 H), 3.59 (d, J = 16.8 Hz, 1 H), 3.71 (d,
J = 16.4 Hz, 1 H), 3.76 (s, 3 H), 4.89 (d, J = 17.2 Hz, 1 H), 5.16 (d,
J = 10.4 Hz, 1 H), 5.94–6.04 (m, 1 H), 6.78 (d, J = 9.2 Hz, 1 H),
6.89–6.93 (m, 1 H), 7.23–7.41 (m, 4 H), 7.74 (d, J = 7.6 Hz, 1 H),
7.87 (d, J = 10.0 Hz, 1 H).
NMR spectra were determined for solutions in CDCl3 with TMS as
internal standard on Bruker DPX-400 and DPX-500 instruments.
13C NMR spectra were determined for solutions in CDCl3 on a
Bruker DPX-400 instrument. Mass spectra were recorded on a Q-
Tof Micro mass spectrometer. CHN was recorded on a Perkin-Elm-
er 2400 series II CHN analyzer. Silica gel (60–120 and 230–400
mesh) was used for chromatographic separations. Silica gel-G [E-
Merck (India)] was used for TLC. Petroleum ether (PE) refers to the
fraction between 60 and 80 °C.
MS: m/z = 495.20 [M + Na]+.
Anal. Calcd for C22H21IN2O2: C, 55.94; H, 4.48; N, 5.93. Found: C,
56.20; H, 4.54; N, 5.93.
N-(5-Allyl-1-methyl-2-oxo-1,2-dihydroquinolin-6-yl)-N-ethyl-
2-(2-iodophenyl)acetamide (2d)
Yield: 750 mg (86%); gummy.
IR (KBr): 1597, 1648, 1661, 2931 cm–1.
5-Allyl-6-(methylamino)coumarin (1a)
This compound was prepared according to a published proce-
dure.13,14 The other starting materials, 1b–d13,14 and 3a,b, were pre-
pared similarly.
1H NMR (400 MHz, CDCl3): d = 1.17 (t, J = 7.2 Hz, 3 H), 3.09–
3.18 (m, 1 H), 3.37 (d, J = 16.4 Hz, 1 H), 3.48 (d, J = 16.4 Hz, 1 H),
3.61 (d, J = 16.4 Hz, 1 H), 3.71 (d, J = 15.2 Hz, 1 H), 3.77 (s, 3 H),
4.27–4.35 (m, 1 H), 4.89 (d, J = 17.2 Hz, 1 H), 5.16 (d, J = 10.0 Hz,
1 H), 5.94–6.03 (m, 1 H), 6.78 (d, J = 9.6 Hz, 1 H), 6.89–6.93 (m, 1
H), 7.19–7.37 (m, 4 H), 7.74 (d, J = 8.0 Hz, 1 H), 7.88 (d, J = 10.0
Hz, 1 H).
N-(5-Allyl-2-oxo-2H-chromen-6-yl)-2-(2-iodophenyl)-N-meth-
ylacetamide (2a); Typical Procedure
A mixture of (2-iodophenyl)acetic acid (500 mg, 1.91 mmol) and
SOCl2 was stirred at 100 °C for 3 h. After evaporation of the sol-
vent, the residue was dissolved in CH2Cl2 (20 mL). A soln of amine
1a (411 mg, 1.91 mmol) in CH2Cl2 (20 mL) and TBAHS (cat.) was
added to the stirred soln of the acid chloride. To this reaction mix-
ture, an aq soln of K2CO3 (556 mg, 4.03 mmol) was added slowly.
After the mixture was stirred at r.t. for 14 h, it was washed with 5%
HCl (2 × 20 mL) and then with 5% aq NaOH (2 × 20 mL). The or-
ganic layer was dried (Na2SO4) and the solvent was evaporated un-
der reduced pressure. The residue was purified by column
chromatography over silica gel (PE–EtOAc, 7:3) to give 2a. The
other compounds, 2b–d and 4a,b, were prepared accordingly.
MS: m/z = 487.23 [M + H]+.
Anal. Calcd for C23H23IN2O2: C, 56.80; H, 4.77; N, 5.76. Found: C,
56.51; H, 4.97; N, 5.47.
N-(2-Allylphenyl)-2-(2-iodophenyl)-N-methylacetamide (4a)
Yield: 918 mg (84%); gummy.
IR (KBr): 1598, 1663, 2923 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.23 (s, 3 H), 3.31–3.37 (m, 2 H),
3.41 (d, J = 15.6 Hz, 1 H), 3.53 (d, J = 16.4 Hz, 1 H), 5.09–5.15 (m,
2 H), 5.87–5.97 (m, 1 H), 6.88–6.92 (m, 1 H), 7.18 (d, J = 7.6 Hz, 1
H), 7.23–7.30 (m, 3 H), 7.33–7.36 (m, 2 H), 7.76 (d, J = 8.0 Hz, 1
H).
Yield: 763 mg (87%); solid; mp 120–121 °C.
IR (KBr): 1593, 1662, 1724, 2929 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.22 (s, 3 H), 3.43 (d, J = 16.0 Hz,
1 H), 3.50 (s, 2 H), 3.64 (d, J = 16.4 Hz, 1 H), 4.89 (d, J = 16.8 Hz,
1 H), 5.18 (d, J = 10.4 Hz, 1 H), 5.93–6.01 (m, 1 H), 6.49 (d, J = 9.6
Hz, 1 H), 6.90–6.93 (m, 1 H), 7.27–7.35 (m, 4 H), 7.74 (d, J = 7.6
Hz, 1 H), 7.87 (d, J = 9.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 31.2, 37.4, 46.6, 101.3, 117.1,
117.3, 117.7, 119.1, 128.4, 128.7, 130.3, 132.0, 134.9, 135.4, 138.3,
138.4, 139.3, 140.5, 154.3, 159.8, 170.2.
MS: m/z = 414.11 [M + Na]+.
Anal. Calcd for C18H18INO: C, 55.26; H, 4.64; N, 3.58. Found: C,
55.32; H, 4.64; N, 3.56.
N-(2-Allylphenyl)-N-ethyl-2-(2-iodophenyl)acetamide (4b)
Yield: 889 mg (86%); solid; mp 79–80 °C.
MS: m/z = 460.11 [M + H]+.
IR (KBr): 1597, 1652, 2922 cm–1.
Anal. Calcd for C21H18INO3: C, 54.92; H, 3.95; N, 3.05. Found: C,
55.20; H, 3.96; N, 3.04.
Synthesis 2011, No. 10, 1569–1574 © Thieme Stuttgart · New York

PAPER
Synthesis of Coumarin- and Quinolone-Annulated Benzazoninone Derivatives
1573
1H NMR (400 MHz, CDCl3): d = 1.16 (t, J = 6.8 Hz, 3 H), 3.13–
3.21 (m, 1 H), 3.35 (d, J = 16.4 Hz, 1 H), 3.37 (s, 2 H), 3.49 (d,
J = 16.4 Hz, 1 H), 4.19–4.27 (m, 1 H), 5.10–5.16 (m, 2 H), 5.87–
5.94 (m, 1 H), 6.87–6.92 (m, 1 H), 7.16 (d, J = 7.6 Hz, 1 H), 7.23–
7.30 (m, 3 H), 7.36 (dd, J = 1.6, 6.8 Hz, 2 H), 7.76 (d, J = 8.0 Hz, 1
H).
13C NMR (100 MHz, CDCl3): d = 29.7, 32.6, 39.9, 44.8, 116.7,
116.8, 117.9, 118.1, 125.8, 126.9, 127.2, 128.1, 129.8, 131.4, 132.4,
137.2, 140.6, 141.3, 146.9, 154.3, 159.8, 170.3.
MS: m/z = 345.20 [M + H]+.
Anal. Calcd for C22H20N2O2: C, 76.72; H, 5.85; N, 8.13. Found: C,
76.68; H, 5.91; N, 8.00.
MS: m/z = 428.09 [M + Na]+.
Anal. Calcd for C19H20INO: C, 56.31; H, 4.97; N, 3.46. Found: C,
56.48; H, 5.18; N, 3.25.
7-Ethyl-4-methyl-14-methylene-7,9,14,15-tetrahydro-3H-qui-
no[6,5-d][3]benzazonine-3,8(4H)-dione (5d)
Yield: 70 mg (63%); gummy.
7-Methyl-14-methylene-14,15-dihydrobenzo[f]chromeno[6,5-
b]azonine-3,8(7H,9H)-dione (5a) by the Heck Reaction; Typical
Procedure
IR (KBr): 1568, 1641, 1665, 2922 cm–1.
1H NMR (500 MHz, CDCl3): d = 1.25 (t, J = 7.2 Hz, 3 H), 3.03 (d,
J = 12.0 Hz, 2 H), 3.28–3.48 (m, 1 H), 3.76 (s, 3 H), 4.13 (d,
J = 11.4 Hz, 2 H), 4.37–4.44 (m, 1 H), 5.01 (s, 1 H), 5.06 (s, 1 H),
6.81 (d, J = 8.0 Hz, 1 H), 7.14–7.18 (m, 4 H), 7.35 (d, J = 10.4 Hz,
2 H), 8.11 (d, J = 8.0 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 12.2, 29.7, 32.6, 39.9, 44.8,
116.2, 116.8, 118.1, 125.8, 126.9, 128.2, 129.5, 129.7, 131.4, 131.9,
132.4, 137.1, 140.6, 141.3, 146.9, 154.3, 159.8, 170.3.
A mixture of 2a (150 mg, 0.33 mmol), TBAB (127.8 mg, 0.39
mmol) and fused KOAc (80.5 mg, 0.82 mmol) was taken up in an-
hyd DMF (10 mL) and N2 was bubbled through. Pd(PPh3)4 (38.1
mg, 10 mol%) was added and the reaction mixture was stirred at
90 °C for 30 min. Then, the reaction mixture was cooled, H2O (20
mL) was added and the mixture was extracted with EtOAc (3 × 20
mL). The combined EtOAc extract was washed with H2O (4 × 10
mL) and brine (10 mL), and dried (Na2SO4). The solvent was dis-
tilled off under reduced pressure to furnish a viscous mass, which
was purified by column chromatography over silica gel (PE–
EtOAc, 4:1) to afford 5a. The other compounds, 5b–d and 7a,b,
were synthesized similarly.
MS: m/z = 359.25 [M + H]+.
Anal. Calcd for C23H22N2O2: C, 77.07; H, 6.19; N, 7.82. Found: C,
77.17; H, 6.19; N, 7.65.
5-Methyl-12-methylene-12,13-dihydro-5H-dibenzo[b,f]azonin-
6(7H)-one (7a)
Yield: 50 mg (49%); solid; mp 165–166 °C.
Yield: 75 mg (69%); solid; mp 118–119 °C.
IR (KBr): 1597, 1648, 1661, 2931 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.18 (s, 3 H), 3.33 (d, J = 14.0 Hz,
1 H), 3.45 (d, J = 5.6 Hz, 1 H), 3.48 (d, J = 3.6 Hz, 1 H), 4.16 (d,
J = 14.4 Hz, 1 H), 5.13 (s, 1 H), 5.36 (s, 1 H), 6.56 (d, J = 10.0 Hz,
1 H), 7.19 (d, J = 7.2 Hz, 2 H), 7.47–7.70 (m, 4 H), 8.21 (d, J = 9.6
Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 29.7, 32.7, 39.6, 116.9, 118.1,
127.4, 128.2, 128.6, 130.9, 132.1, 132.4, 133.3, 136.3, 139.0, 141.1,
143.8, 146.7, 154.3, 159.7, 170.9.
IR (KBr): 1595, 1651, 2925 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.16 (d, J = 12.8 Hz, 2 H), 3.29 (s,
3 H), 3.49 (d, J = 14.4 Hz, 2 H), 5.06 (s, 1 H), 5.19 (s, 1 H), 6.50 (d,
J = 16.4 Hz, 1 H), 7.13–7.18 (m, 3 H), 7.32–7.35 (m, 4 H).
13C NMR (100 MHz, CDCl3): d = 34.5, 35.8, 36.7, 124.8, 126.8,
127.3, 127.8, 128.4, 129.0, 129.4, 130.7, 133.2, 134.0, 134.3, 137.4,
137.9, 141.3, 170.0.
MS: m/z = 286.19 [M + Na]+.
HRMS: m/z [M + Na]+ calcd for C21H17NNaO3: 354.1106; found:
Anal. Calcd for C18H17NO: C, 82.10; H, 6.51; N, 5.32. Found: C,
81.85; H, 6.51; N, 5.23.
354.1274.
7-Ethyl-14-methylene-14,15-dihydrobenzo[f]chromeno[6,5-
b]azonine-3,8(7H,9H)-dione (5b)
Yield: 73 mg (67%); solid; mp 150–151 °C.
5-Ethyl-12-methylene-12,13-dihydro-5H-dibenzo[b,f]azonin-
6(7H)-one (7b)
Yield: 49 mg (48%); solid; mp 92–94 °C.
IR (KBr): 1595, 1657, 2923 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.13 (t, J = 7.2 Hz, 3 H), 2.95 (d,
J = 11.4 Hz, 2 H), 3.30–3.37 (m, 1 H), 3.50 (d, J = 14.8 Hz, 2 H),
3.36–3.88 (m, 1 H), 5.16 (s, 1 H), 5.39 (s, 1 H), 6.26 (d, J = 10.4 Hz,
1 H), 7.10–7.23 (m, 3 H), 7.28–7.35 (m, 4 H).
IR (KBr): 1590, 1636, 1734, 2929 cm–1.
1H NMR (400 MHz, CDCl3): d = 0.97 (t, J = 7.2 Hz, 3 H), 3.32 (d,
J = 13.6 Hz, 1 H), 3.36–3.47 (m, 3 H), 4.04–4.11 (m, 1 H), 4.16 (d,
J = 14.8 Hz, 1 H), 5.13 (s, 1 H), 5.34 (s, 1 H), 6.57 (d, J = 10.0 Hz,
1 H), 7.09 (d, J = 7.6 Hz, 2 H), 7.29–7.44 (m, 4 H), 8.22 (d, J = 10.0
Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 13.3, 34.4, 37.1, 43.5, 125.7,
126.8, 127.3, 128.2, 128.7, 129.4, 130.8, 133.2, 133.7, 134.3, 134.8,
137.7, 138.0, 141.2, 170.2.
13C NMR (100 MHz, CDCl3): d = 29.7, 32.0, 37.1, 40.3, 114.5,
122.6, 126.7, 127.1, 127.3, 130.0, 130.9, 131.6, 131.8, 133.3, 134.1,
134.5, 138.3, 138.8, 146.1, 154.5, 160.2, 172.4.
MS: m/z = 278.29 [M + H]+.
MS: m/z = 368.17 [M + Na]+.
Anal. Calcd for C19H19NO: C, 82.28; H, 6.90; N, 5.05. Found: C,
82.36; H, 6.84; N, 5.07.
Anal. Calcd for C22H19NO3: C, 76.50; H, 5.54; N, 4.06. Found: C,
76.43; H, 5.53; N, 4.11.
4,7-Dimethyl-14-methylene-7,9,14,15-tetrahydro-3H-qui-
no[6,5-d][3]benzazonine-3,8(4H)-dione (5c)
Yield: 67 mg (61%); gummy.
IR (KBr): 1566, 1641, 1667, 2920 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.18 (s, 3 H), 3.30 (d, J = 13.6 Hz,
1 H), 3.31 (d, J = 13.6 Hz, 1 H), 3.45 (t, J = 12.0 Hz, 1 H), 3.77 (s,
3 H), 4.29 (d, J = 15.2 Hz, 1 H), 5.10 (s, 1 H), 5.42 (s, 1 H), 6.86 (d,
J = 10.0 Hz, 1 H), 7.37 (d, J = 8.8 Hz, 2 H), 7.42–7.49 (m, 4 H),
8.24 (d, J = 10.0 Hz, 1 H).
Acknowledgment
We thank the CSIR (New Delhi) for financial assistance. Two of us
(T.G. and S.S.) are grateful to the CSIR (New Delhi) for research
fellowships. We also thank the DST (New Delhi) for providing a
CHN analyzer and NMR and IR spectrometers under the DST-FIST
program.
Synthesis 2011, No. 10, 1569–1574 © Thieme Stuttgart · New York

1574
K. C. Majumdar et al.
PAPER
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