Regioselective synthesis of dihydropyridocoumarin and phenanthrolinone derivatives-via iron(III) chloride mediated intramolecular cyclization

Article abstract of DOI:10.1055/s-0033-1340902

Potentially bioactive angular dihydropyridocoumarin and phenanthrolinone derivatives are synthesized in good to excellent yields using readily available iron(III) chloride (FeCl₃) as the catalyst. The process is very simple, straightforward and inexpensive, and provides a diverse range of pyranoquinolone or phenan-throlinone derivatives, via a 6-endo-dig mode of cyclization, starting from simple and easily available 6-(N-propargyl) aminocoumarin and -quinolone derivatives. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0033-1340902

PAPER
▌1413
paper
Regioselective Synthesis of Dihydropyridocoumarin and Phenanthrolinone
Derivatives via Iron(III) Chloride Mediated Intramolecular Cyclization
Dihydropyridocoumarins and Phenanthrolines
K. C. Majumdar,* Sudipta Ponra
Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India
Fax +91(33)25828282; E-mail: kcmklyuniv@gmail.com
Received: 17.12.2013; Accepted after revision: 13.02.2014
velopment of sustainable, environmentally friendly and
Abstract: Potentially bioactive angular dihydropyridocoumarin
low-cost C–C and C–X bond forming protocols have at-
and phenanthrolinone derivatives are synthesized in good to excel-
tracted significant attention from the synthetic organic
chemistry community. Therefore, it is not surprising that
lent yields using readily available iron(III) chloride (FeCl3) as the
catalyst. The process is very simple, straightforward and inexpen-
sive, and provides a diverse range of pyranoquinolone or phenan- iron salts have received much attention as alternative and
throlinone derivatives, via a 6-endo-dig mode of cyclization,
starting from simple and easily available 6-(N-propargyl)aminocou-
marin and -quinolone derivatives.
promising catalysts for many selective organic transfor-
mations.25 Among various iron salts, iron(III) chloride has
been used as a Lewis acid to catalyze the Friedel–Crafts
reaction,26 the synthesis of esters and acetals,27 the α-gly-
Key words: pyranoquinolone, phenanthrolinone, iron(III) chloride,
Sonogashira coupling, 6-endo-dig cyclization
cosidation of peracetylated sugars28 and the cyclization of
2-(trimethylsilylmethyl)pentadienal.29 In continuation of
our work on the development of efficient protocols for the
Naturally occurring quinoline derivatives are among
some of the earliest discovered compounds found to pos-
sess remarkable biological activities,1 and they have been
utilized for the treatment of a various diseases. Com-
pounds containing a quinoline motif are widely used as
structural frameworks in a large number of biologically
active natural products and pharmaceuticals.2 They have
also found application as antimalarials,3 antibacterials,4
antifungals5 and anticancer agents.6 Moreover, quinoline
derivatives are used in materials science,7 bioorganome-
tallic processes,8 and for the syntheses of fungicides, viru-
cides, biocides, alkaloids, rubber chemicals and flavoring
agents. Due to their potential biological activities,9 cou-
marins fused with heterocycles have received increasing
attention and are common structural motifs in many
natural products.10 Helietidine, dutadrupine, and
geibalansine11 are examples of natural products contain-
ing the pyranoquinoline core structure. Moreover, pyra-
no[3,2-f]quinolines, which are a combination of both a
quinoline ring and a pyran moiety demonstrate unique bi-
ological activities, including psychotropic,12 anti-aller-
gic,13 anti-inflammatory14 and estrogenic,15 and are used
as potential pharmaceuticals.16 4,7-Phenanthroline deriv-
atives and their analogues exhibit high antibacterial activ-
ity and are used for the treatment of gastrointestinal
diseases.17–22
synthesis of pharmacologically important and potentially
bioactive heterocyclic systems,30 we decided to investi-
gate whether iron(III) chloride could be used to catalyze
the cyclization of various 6-(N-propargyl)aminocoumarin
and -quinolone derivatives. Herein we report the results of
our studies.
We previously observed30n,31 two different results from
the iron(III) chloride mediated reactions of N-aryl-N-(2-
alkynyl)toluenesulfonamides 1 and N-(1,3-dimethyl-2,4-
dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-4-methyl-N-(3-
phenylprop-2-ynyl)benzenesulfonamide (3). As com-
pound 1 gave the substituted quinoline derivatives 2 via
iron(III) chloride mediated cyclization,21 we hypothesized
that compound 3 might also undergo a similar type of re-
action to give the corresponding cyclized product. How-
ever, in practice, the reaction of 3 with iron(III) chloride
furnished different results. This unexpected outcome
prompted us to investigate a similar reaction of alkyne 7a
with iron(III) chloride (1 equiv) in 1,2-dichloroethane for
24 hours. The expected detosylated aromatized product 10
was not obtained. However, the reaction afforded a mix-
ture of cyclized tosylated product 9a in good yield (72%),
along with coumarin 8 as a decomposition side product
(Scheme 1). The structure of product 9a was established
from its elemental analysis and spectral data.
The precursors 7 for the present investigation were ac-
cessed according to our earlier published procedure, as
shown in Scheme 2.32 The optimized conditions for the
iron(III) chloride mediated cyclization to give compounds
9 were established by screening different parameters.
The toxicity and prohibitive prices of catalysts derived
from heavy or rare metals constitute severe drawbacks in
their use in large-scale applications in organic chemistry.
Iron is one of the most abundant metals on earth, and is in-
expensive and environmentally friendly.23 Moreover, iron
salts and complexes are commercially available.24 The de-
The investigation was initiated using compound 7a as a
model substrate and the results are summarized in Table
1. Alkyne 7a was initially treated with iron(III) chloride (1
equiv) in 1,2-dichloroethane at room temperature, but no
reaction occurred (Table 1, entry 1).
SYNTHESIS 2014, 46, 1413–1420
Advanced online publication: 24.03.2014
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
DOI: 10.1055/s-0033-1340902; Art ID: SS-2013-Z0816-OP
© Georg Thieme Verlag Stuttgart · New York

1414
K. C. Majumdar, S. Ponra
PAPER
Ts
N
N
FeCl3 (1 equiv)
DCE, reflux
(previous work31
)
R1
R1
R2
R2
2
1
Ts
Ts
N
O
O
Ts
N
O
Ts
O
Me
O
N
Me
O
Ph
Me
NH
N
FeCl3 (1 equiv)
DCE, reflux, 24 h
Me
O
N
N
N
(previous work30n
)
+
+
O
N
Ph
N
O
N
N
OH
Me
Me
Me
Ph
Me
3
4 (60%)
5 (20%)
6 (15%)
EtO
NHTs
+
NTs
EtO
FeCl3 (1 equiv)
O
O
DCE, reflux
24 h
O
O
8 (22%)
9a (72%)
(formed)
EtO
NTs
O
O
N
FeCl3 (1 equiv)
7a
DCE, reflux
24 h
O
O
10
(expected but not formed)
Scheme 1 Iron(III) chloride mediated reactions of substrates 1, 3 and 7a
We then attempted the same reaction by heating at reflux product 9a (Table 1, entry 8). Next the effect of different
temperature in the presence of iron(III) chloride (0.1 solvents (EtOH, CHCl3, CH2Cl2, THF, MeCN) on the
equiv), and this reaction gave the cyclized product 9a, but yield of pyranoquinoline derivative 9a was studied (Table
in only 15% yield (Table 1, entry 2). The number of equiv- 1, entries 9–13). Among these solvents, acetonitrile was
alents of iron(III) chloride was then gradually increased found to give the highest yield (76%) of the product (Ta-
from 0.1–2.0 equivalents. It was found that one equivalent ble 1, entry 13). The same reaction was also performed in
of iron(III) chloride gave the best yield of the cyclized the presence of iron(III) chloride for 10 hours (Table 1,
product 9a (Table 1, entries 3–6). Pleasingly, reducing the entry 14), but a lower yield was obtained. Thus the opti-
reaction time from 24 hours to 12 hours resulted in the mized conditions for this transformation are as follows:
same yield of the product 9a (Table 1, entry 7). However, iron(III) chloride (1 equiv) as the catalyst, acetonitrile as
a reaction time of less than 12 hours resulted in incom- the solvent, reflux, 12 hours.
plete conversion, and consequently, a lower yield of the
I
NHTs
R
(i)
R
NTs
(ii)
O
X
NTs
8
O
X
11
O
X
7
Scheme 2 Reagents and conditions: (i) progargyl bromide, anhydrous K2CO3, NaI, anhydrous acetone, reflux, 6 h; (ii) Pd(PPh3)2Cl2, CuI (3
mol%), Et3N, DMF, r.t., 2 h.
Synthesis 2014, 46, 1413–1420
© Georg Thieme Verlag Stuttgart · New York

PAPER
Dihydropyridocoumarins and Phenanthrolinones
1415
entries 11–14). However, similar reactions of substrates
7o–q (where R1 = Me or H) completely failed to give any
cyclized product (Table 2, entries 15–17). These reactions
also follow the same pattern as discussed earlier.
Table 1 Optimization of the Reaction Conditions
EtO
EtO
Table 2 Synthesis of Various Pyridocoumarins and Pyridoquino-
lones
NTs
NTs
O
O
9a
O
O
7a
R1
R1
Entry Catalyst (equiv) Solvent Temp
Time (h) Yield (%)a
FeCl3 (1 equiv)
NR2
NR2
MeCN, reflux, 12 h
1
2
FeCl3 (1.0)
FeCl3 (0.1)
FeCl3 (0.2)
FeCl3 (0.5)
FeCl3 (2.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
FeCl3 (1.0)
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
EtOH
CHCl3
r.t.
24
24
24
24
24
24
12
6
0
15
41
63
72
72
72
53
34
24
19
21
76
71
O
X
O
X
reflux
reflux
reflux
reflux
reflux
reflux
reflux
reflux
reflux
9
7
3
Entry Substrate X
R1
R2
Product Yield
4
1
2
7a
7b
7c
7d
7e
7f
O
4-OEt
Ts
Ts
Ts
Ts
Ts
9a
9b
9c
9d
9e
9f
–
76
71
76
74
72
66
0
5
O
2-OEt
6
3
O
4-Oi-Pr
2-OMe
4-OBn
7
4
O
8
5
O
9
12
12
12
12
12
10
6
O
4-OCH2CH=CH2 Ts
10
11
12
13
14
7
7g
7h
7i
O
H
Ts
Ts
Ts
Et
CH2Cl2 reflux
THF reflux
MeCN reflux
MeCN reflux
8
O
4-Me
4-Ac
4-OMe
4-Oi-Pr
4-OEt
4-OMe
4-OEt
4-Me
4-Me
H
–
0
FeCl3 (1.0)
9
O
–
0
FeCl3 (1.0)
10
11
12
13
14
15
16
17
7j
O
–
0
FeCl3 (1.0)
7k
7l
NMe
NMe
NMe
NEt
NMe
NEt
NMe
Ts
Ts
Ts
Ts
Ts
Ts
Ts
9g
9h
9i
9j
–
75
69
63
68
0
a Yield of isolated product.
7m
7n
7o
7p
7q
To test the scope and generality of this process, substrates
7b–j were subjected to this transformation under the opti-
mized reaction conditions, and the results are summarized
in Table 2. The reactions of alkynes 7a–f (R1 = OEt, OMe,
Oi-Pr, OBn or OCH2CH=CH2) gave the corresponding
cyclized adducts 9a–f in yields of 66–76% (Table 2, en-
tries 1–6). However, the reaction failed in the case of the
substrate 7g (R1 = H; Table 2, entry 7), and full recovery
of the starting material was possible, even after 12 hours.
The same outcomes were obtained (recovery of the start-
ing materials) in the cases of substrates 7h,i (R1 = Me or
Ac; Table 2, entries 8 and 9). The reaction also failed
when the tosyl group (R2) was replaced by an ethyl group
(substrate 7j; Table 2, entry 10). From these results, it can
be concluded that for the alkynes 7 (where X = O), the re-
action is only successful with substrates containing a tosyl
group and strong electron-donating groups at positions 2
or 4 of the aromatic ring adjacent to the alkyne moiety.
Encouraged by these results, substrates 7k–n (X = NMe
or NEt) were reacted under the optimized conditions, and
pleasingly, the expected substituted phenanthrolinone de-
rivatives 9g–j were obtained in 63–75% yields (Table 2,
–
0
–
0
A plausible reaction mechanism for the iron(III) chloride
mediated formation of substituted quinoline derivatives is
depicted in Scheme 3. Initially, the alkyne moiety is acti-
vated by iron(III) chloride to generate the π-complex A,
which on subsequent intramolecular 6-endo-dig cycliza-
tion can produce the charged species B. Intermediate B,
on simultaneous deprotonation and loss of iron(III) chlo-
ride (protodemetalation) produces the final product 9. The
reason behind the failure of the reaction in the absence of
a tosyl group may be due to the fact that the lone pair of
the nitrogen atom in the N-ethyl group captured the
iron(III) chloride, and thus prevented the cyclization step
taking place. Moreover, the reaction only occurs when a
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 1413–1420

1416
K. C. Majumdar, S. Ponra
PAPER
FeCl3
NTs
FeCl3
R
R
FeCl3
R
H
R
FeCl3
NTs
6-endo-dig
NTs
NTs
– H+/+ H+
O
X
O
X
O
X
O
X
B
A
7
9
Scheme 3 Proposed mechanism for the iron(III) chloride mediated synthesis
H), 6.79 (d, J = 8.8 Hz, 2 H), 7.10 (d, J = 8.8 Hz, 2 H), 7.22 (d,
J = 8.0 Hz, 1 H), 7.25–7.27 (m, 2 H), 7.41 (dd, J = 2.4 Hz, 8.8 Hz,
1 H), 7.55–7.61 (m, 3 H), 7.65 (d, J = 9.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 14.7, 21.6, 42.1, 63.6, 81.5, 86.3,
113.8, 114.4, 117.3, 117.5, 119.1, 128.1, 128.4, 129.5, 131.5, 132.9,
135.4, 136.0, 143.0, 144.0, 153.2, 159.3, 160.3.
strong electron-donating group is present at the 2 and/or 4
position of the aromatic ring adjacent to the alkyne moi-
ety. This is because the strong electron-donating group is
able to activate the alkyne moiety such that it can form the
π-complex A, which subsequently cyclizes to give the de-
sired product. In other words, the availability of the nitro-
gen lone pair is reduced by the presence of the tosyl group.
As a result, iron(III) chloride is free to form the aforemen-
tioned π-complex and thereby facilitates the 6-endo-dig
cyclization to yield the product.
MS (ESI): m/z = 474.00 [M + H]+ (100%).
Anal. Calcd for C27H23NO5S: C, 68.48; H, 4.90; N, 2.96. Found: C,
68.30; H, 4.95; N, 3.00.
N-[3-(2-Ethoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(2-oxo-2H-
chromen-6-yl)benzenesulfonamide (7b)
Yield: 556 mg (83%); pale grey solid; mp 142–144 °C.
IR (KBr): 1596, 1733, 2242, 2978 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.25–1.33 (m, 3 H), 2.32 (s, 3 H),
4.00 (q, J = 6.8 Hz, 2 H), 4.72 (s, 2 H), 6.45 (d, J = 9.6 Hz, 1 H),
6.84 (q, J = 8.0 Hz, 2 H), 7.10–7.15 (m, 3 H), 7.23–7.27 (m, 2 H),
7.52–7.67 (m, 5 H).
13C NMR (100 MHz, CDCl3): δ = 14.7, 21.5, 42.3, 64.0, 83.0, 86.7,
111.5, 111.7, 117.2, 117.4, 119.0, 120.2, 128.1, 128.5, 129.4, 130.1,
131.4, 133.5, 135.3, 136.1, 143.1, 143.9, 153.2, 159.5, 160.3.
To summarize, we have successfully developed a simple,
straightforward, inexpensive and efficient methodology
for the synthesis of potentially bioactive pyranoquinoline
and phenanthrolinone derivatives. The process utilizes
readily available starting materials and involves an
iron(III) chloride catalyzed intramolecular 6-endo-dig
mode of cyclization.
Silica gel [Rankem (India), 60–120 or 230–400 mesh] was used for
chromatographic separation. Silica gel-G [CDH (India)] was used
for TLC. Petroleum-ether (PE) refers to the fraction boiling be-
tween 60–80 °C. Melting points were determined in open capillar-
ies using a metal bath apparatus [Sunbeam (India)] and are
uncorrected. IR spectra were run as KBr discs on a Perkin-Elmer
120-000A apparatus. 1H and 13C NMR spectra were recorded on a
Bruker DPX-400 instrument as solutions in CDCl3, with TMS as the
internal standard. Mass spectra were recorded on a Qtof Micro in-
strument. CHN analyses were obtained using a Perkin Elmer 2400
series II CHN analyzer.
MS (ESI): m/z = 474.00 [M + H]+ (100%).
Anal. Calcd for C27H23NO5S: C, 68.48; H, 4.90; N, 2.96. Found: C,
68.27; H, 4.94; N, 3.02.
N-[3-(4-Isopropoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(2-oxo-
2H-chromen-6-yl)benzenesulfonamide (7c)
Yield: 600 mg (87%); pale grey solid; mp 120–122 °C.
IR (KBr): 1594, 1730, 2240, 2972 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.33 (d, J = 6.0 Hz, 6 H), 2.38 (s,
3 H), 4.53 (m, 1 H), 4.65 (s, 2 H), 6.45 (d, J = 9.6 Hz, 1 H), 6.77 (d,
J = 8.8 Hz, 2 H), 7.09 (d, J = 8.8 Hz, 2 H), 7.21–7.27 (m, 3 H), 7.41
(dd, J = 2.4 Hz, 8.8 Hz, 1 H), 7.54–7.58 (m, 3 H), 7.65 (d, J = 9.6
Hz, 1 H).
Compounds 7g,h,m,o,q were prepared according to a previously
published procedure.32
Alkynes 7; General Procedure
To a stirred solution of compound 11 (500 mg, 1 equiv), the appro-
priate iodobenzene (1.2 equiv) and anhydrous Et3N (2 mL) in anhy-
drous DMF (8 mL) were added the catalysts Pd(PPh3)2Cl2 (0.05
equiv) and CuI (0.05 equiv). The reaction mixture was stirred at
room temperature for 1 h. After completion, the reaction mixture
was poured into H2O (20 mL) and extracted with CH2Cl2 (3 × 20
mL). The organic layer was successively washed with H2O (5 × 20
mL), brine (20 mL) and dried over anhydrous Na2SO4. The solvent
was removed under reduced pressure to give a crude mass which
was chromatographed over silica gel (60–120 mesh) using EtOAc–
PE (1:9) as eluent to afford the product 7.
13C NMR (100 MHz, CDCl3): δ = 21.6, 21.9, 42.1, 69.9, 81.4, 86.3,
113.6, 115.6, 117.3, 117.4, 119.1, 128.1, 128.4, 129.5, 131.5, 133.0,
135.3, 135.9, 143.0, 144.0, 153.2, 158.3, 160.3.
MS (ESI): m/z = 488.12 [M + H]+ (100%).
Anal. Calcd for C28H25NO5S: C, 68.98; H, 5.17; N, 2.87. Found: C,
68.87; H, 5.14; N, 2.94.
N-[3-(2-Methoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(2-oxo-
2H-chromen-6-yl)benzenesulfonamide (7d)
Yield: 592 mg (91%); pale grey solid; mp 142–144 °C.
IR (KBr): 1696, 1732, 2236, 2923 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.33 (s, 3 H), 3.75 (s, 3 H), 4.72
(s, 2 H), 6.44 (d, J = 9.2 Hz, 1 H), 6.85 (q, J = 8.0 Hz, 2 H), 7.10 (d,
J = 7.2 Hz, 1 H), 7.16 (d, J = 7.6 Hz, 2 H), 7.28 (q, J = 7.2 Hz, 2 H),
7.53–7.65 (m, 5 H).
N-[3-(4-Ethoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(2-oxo-2H-
chromen-6-yl)benzenesulfonamide (7a)
Yield: 576 mg (86%); pale grey solid; mp 144–146 °C.
IR (KBr): 1569, 1732, 2238, 2922 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.41 (t, J = 7.2 Hz, 3 H), 2.39 (s,
3 H), 4.02 (q, J = 7.2 Hz, 2 H), 4.70 (s, 2 H), 6.46 (d, J = 9.6 Hz, 1
Synthesis 2014, 46, 1413–1420
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PAPER
Dihydropyridocoumarins and Phenanthrolinones
1417
13C NMR (100 MHz, CDCl3): δ = 21.5, 42.3, 55.6, 82.9, 87.0,
110.5, 111.2, 117.2, 117.3, 119.0, 120.4, 128.1, 128.5, 129.4, 130.2,
131.8, 133.2, 135.3, 136.0, 143.1, 143.9, 153.2, 160.1, 160.3.
J = 2.8 Hz, 9.2 Hz, 1 H), 7.24–7.39 (m, 3 H), 7.67 (d, J = 9.2 Hz, 1
H).
13C NMR (100 MHz, CDCl3): δ = 12.4, 41.0, 46.1, 55.3, 83.5, 84.1,
111.2, 113.7, 113.9, 114.8, 116.7, 117.4, 119.0, 119.3, 132.3, 133.1,
143.9, 145.1, 146.8, 159.6, 161.5.
MS (ESI): m/z = 460.07 [M + H]+ (100%).
Anal. Calcd for C26H21NO5S: C, 67.96; H, 4.61; N, 3.05. Found: C,
68.07; H, 4.66; N, 3.08.
MS (ESI): m/z = 334.14 [M + H]+ (100%).
Anal. Calcd for C21H19NO3: 75.66; H, 5.74; N, 4.20. Found: C,
75.46; H, 5.81; N, 4.29.
N-{3-[4-(Benzyloxy)phenyl]prop-2-yn-1-yl}-4-methyl-N-(2-
oxo-2H-chromen-6-yl)benzenesulfonamide (7e)
Yield: 621 mg (82%); pale grey solid; mp 134–136 °C.
N-[3-(4-Isopropoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(1-
methyl-2-oxo-1,2-dihydroquinolin-6-yl)benzenesulfonamide
(7k)
Yield: 581 mg (85%); pale grey solid; mp 110–112 °C.
IR (KBr): 1681, 1702, 2222, 2951 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.33 (d, J = 6.0 Hz, 6 H), 2.38 (s,
3 H), 3.69 (s, 3 H), 4.53 (t, J = 6.0 Hz, 1 H), 4.67 (s, 2 H), 6.71 (d,
J = 8.8 Hz, 1 H), 6.77 (d, J = 8.4 Hz, 1 H), 7.09 (d, J = 8.4 Hz, 2 H),
7.22 (d, J = 8.0 Hz, 2 H), 7.31 (d, J = 8.8 Hz, 1 H), 7.46–7.69 (m, 6
H).
IR (KBr): 1693, 1732, 2228, 2991 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.38 (s, 3 H), 4.65 (s, 2 H), 5.06
(s, 2 H), 6.46 (d, J = 9.2 Hz, 1 H), 6.87 (d, J = 8.8 Hz, 2 H), 7.11 (d,
J = 8.8 Hz, 2 H), 7.22 (d, J = 7.6 Hz, 2 H), 7.25–7.27 (m, 2 H),
7.34–7.40 (m, 5 H), 7.55–7.58 (m, 3 H), 7.65 (d, J = 9.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.6, 42.1, 70.0, 81.7, 86.1,
114.3, 114.8, 117.3, 117.5, 119.1, 127.4, 128.1, 128.2, 128.4, 128.7,
129.5, 131.4, 133.0, 135.4, 135.9, 136.4, 143.0, 144.0, 153.2, 159.0,
160.3.
13C NMR (100 MHz, CDCl3): δ = 21.6, 21.9, 29.6, 42.2, 69.9, 81.7,
86.1, 113.7, 114.8, 115.5, 120.8, 122.4, 128.1, 128.5, 128.6, 129.4,
130.8, 131.9, 132.0, 132.1, 133.0, 133.9, 135.6, 138.7, 139.5, 143.8,
158.2, 160.2.
MS (ESI): m/z = 536.11 [M + H]+ (100%).
Anal. Calcd for C32H25NO5S: C, 71.76; H, 4.70; N, 2.62. Found: C,
71.90; H, 4.75; N, 2.70.
MS (ESI): m/z = 501.19 [M + H]+ (100%).
N-{3-[4-(Allyloxy)phenyl]prop-2-yn-1-yl}-4-methyl-N-(2-oxo-
2H-chromen-6-yl)benzenesulfonamide (7f)
Anal. Calcd for C29H28N2O4S: C, 69.58; H, 5.64; N, 5.60. Found: C,
69.77; H, 5.67; N, 5.48.
Yield: 577 mg (84%); pale grey solid; mp 120–122 °C.
IR (KBr): 1692, 1731, 2230, 2997 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.38 (s, 3 H), 4.52 (dd, J = 1.2 Hz,
4.0 Hz, 2 H), 4.65 (s, 2 H), 5.30 (dd, J = 1.2 Hz, 10.4 Hz, 1 H), 5.41
(dd, J = 1.2 Hz, 9.2 Hz, 1 H), 5.98–6.05 (m, 1 H), 6.45 (d, J = 9.6
Hz, 1 H), 6.81 (d, J = 8.8 Hz, 2 H), 7.10 (dd, J = 2.0 Hz, 9.2 Hz, 2
H), 7.20–7.28 (m, 3 H), 7.41 (dd, J = 2.4 Hz, 8.8 Hz, 1 H), 7.54–
7.58 (m, 3 H), 7.66 (d, J = 9.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.6, 42.1, 68.8, 81.6, 86.1,
114.1, 114.7, 117.2, 117.5, 118.0, 119.1, 128.0, 128.4, 129.5, 131.5,
132.7, 132.9, 135.3, 135.9, 143.1, 144.1, 153.2, 158.9, 160.3.
N-[3-(4-Ethoxyphenyl)prop-2-yn-1-yl]-4-methyl-N-(1-methyl-
2-oxo-1,2-dihydroquinolin-6-yl)benzenesulfonamide (7l)
Yield: 611 mg (92%); pale grey solid; mp 144–146 °C.
IR (KBr): 1646, 1702, 2220, 2991 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.40 (t, J = 7.2 Hz, 3 H), 2.38 (s,
3 H), 3.69 (s, 3 H), 4.02 (q, J = 6.8 Hz, 2 H), 4.67 (s, 2 H), 6.72 (d,
J = 9.2 Hz, 1 H), 6.78 (d, J = 8.4 Hz, 2 H), 7.10 (d, J = 8.4 Hz, 2 H),
7.22 (d, J = 8.0 Hz, 2 H), 7.31 (d, J = 8.8 Hz, 1 H), 7.49–7.59 (m, 5
H).
13C NMR (100 MHz, CDCl3): δ = 14.7, 21.6, 29.6, 42.2, 63.5, 81.8,
86.0, 113.9, 114.4, 114.8, 120.8, 122.4, 128.1, 128.6, 129.4, 130.8,
132.9, 133.9, 135.6, 138.7, 139.5, 143.8, 159.2, 162.2.
MS (ESI): m/z = 486.21 [M + H]+ (100%).
Anal. Calcd for C28H23NO5S: C, 69.26; H, 4.77; N, 2.88. Found: C,
69.10; H, 4.81; N, 2.81.
MS (ESI): m/z = 487.24 [M + H]+ (100%).
N-[3-(4-Acetylphenyl)prop-2-yn-1-yl]-4-methyl-N-(2-oxo-2H-
chromen-6-yl)benzenesulfonamide (7i)
Yield: 547 mg (82%); pale grey solid; mp 126–128 °C.
Anal. Calcd for C28H26N2O4S: C, 69.11; H, 5.39; N, 5.76. Found: C,
68.90; H, 5.44; N, 5.70.
IR (KBr): 1686, 1729, 2228, 2969 cm–1.
N-[3-(4-Ethoxyphenyl)prop-2-yn-1-yl]-N-(1-ethyl-2-oxo-1,2-di-
hydroquinolin-6-yl)-4-methylbenzenesulfonamide (7n)
Yield: 553 mg (84%); pale grey solid; mp 128–130 °C.
IR (KBr): 1642, 1702, 2217, 2981 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.35 (t, J = 7.2 Hz, 3 H), 1.41 (t,
J = 7.2 Hz, 3 H), 2.39 (s, 3 H), 4.02 (t, J = 6.8 Hz, 2 H), 4.34 (d,
J = 7.2 Hz, 2 H), 4.67 (s, 2 H), 6.71 (d, J = 9.6 Hz, 1 H), 6.78 (d,
J = 8.8 Hz, 2 H), 7.10 (d, J = 8.8 Hz, 2 H), 7.22 (d, J = 8.0 Hz, 2 H),
7.33 (d, J = 8.8 Hz, 1 H), 7.50–7.56 (m, 3 H), 7.61 (d, J = 8.4 Hz, 2
H).
1H NMR (400 MHz, CDCl3): δ = 2.40 (s, 3 H), 2.59 (s, 3 H), 4.70
(s, 2 H), 6.47 (d, J = 9.6 Hz, 1 H), 7.23–7.28 (m, 5 H), 7.39 (dd,
J = 2.4 Hz, 8.8 Hz, 1 H), 7.54–7.58 (m, 3 H), 7.64 (d, J = 9.6 Hz, 1
H), 7.87 (d, J = 8.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 21.6, 26.6, 42.0, 85.3, 86.4,
117.3, 117.5, 119.2, 126.7, 128.0, 128.2, 128.3, 129.6, 131.3, 131.6,
135.2, 135.7, 136.6, 143.0, 144.3, 153.3, 160.2, 197.2.
MS (ESI): m/z = 472.09 [M + H]+ (100%).
Anal. Calcd for C27H21NO5S: C, 68.77; H, 4.49; N, 2.97. Found: C,
68.90; H, 4.51; N, 2.91.
13C NMR (100 MHz, CDCl3): δ = 12.7, 14.7, 21.6, 37.5, 42.3, 63.5,
81.8, 86.0, 114.0, 114.4, 114.7, 121.1, 122.5, 128.1, 128.8, 129.4,
130.9, 132.9, 133.7, 135.8, 138.5, 138.6, 143.8, 159.2, 161.7.
6-{Ethyl[3-(4-methoxyphenyl)prop-2-yn-1-yl]amino}-2H-chro-
men-2-one (7j)
Yield: 668 mg (91%); yellow gum.
IR (KBr): 1569, 1679, 1720, 2969 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.26 (t, J = 7.2 Hz, 3 H), 3.51 (q,
J = 7.2 Hz, 2 H), 3.78 (s, 3 H), 4.23 (s, 2 H), 6.40 (d, J = 9.6 Hz, 1
H), 6.81 (d, J = 8.4 Hz, 2 H), 6.88 (d, J = 2.8 Hz, 1 H), 7.12 (dd,
MS (ESI): m/z = 501.14 [M + H]+ (100%).
Anal. Calcd for C29H28N2O4S: C, 69.58; H, 5.64; N, 5.60. Found: C,
69.70; H, 5.58; N, 5.70.
N-(1-Ethyl-2-oxo-1,2-dihydroquinolin-6-yl)-4-methyl-N-(3-p-
tolylprop-2-yn-1-yl)benzenesulfonamide (7p)
Yield: 532 mg (86%); pale grey solid; mp 130–132 °C.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 1413–1420

1418
K. C. Majumdar, S. Ponra
PAPER
IR (KBr): 1509, 1590, 1645, 1656, 2973 cm–1.
6.71 (d, J = 8.4 Hz, 2 H), 6.95–7.00 (m, 3 H), 7.32–7.35 (m, 3 H),
8.08 (d, J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.3, 22.0, 45.2, 70.0, 114.5,
115.3, 115.8, 117.1, 124.9, 127.5, 128.2, 129.0, 129.3, 130.7, 131.9,
133.7, 136.1, 136.7, 141.4, 143.7, 153.6, 157.7, 159.9.
1H NMR (400 MHz, CDCl3): δ = 1.34 (t, J = 7.2 Hz, 3 H), 2.33 (s,
3 H), 2.38 (s, 3 H), 4.33 (q, J = 6.8 Hz, 2 H), 4.68 (s, 2 H), 6.70 (d,
J = 9.6 Hz, 1 H), 7.06 (m, 4 H), 7.22 (d, J = 8.0 Hz, 2 H), 7.33 (d,
J = 8.8 Hz, 1 H), 7.50–7.56 (m, 3 H), 7.61 (d, J = 8.0 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 12.8, 21.5, 21.6, 37.6, 42.3, 82.7,
86.1, 114.7, 119.0, 121.1, 122.5, 128.1, 128.9, 129.0, 129.4, 130.9,
131.3, 133.6, 135.7, 138.6, 138.7, 138.9, 143.8, 161.7.
MS (ESI): m/z = 488.19 [M + H]+ (100%).
Anal. Calcd for C28H25NO5S: C, 68.98; H, 5.17; N, 2.87. Found: C,
68.84; H, 5.15; N, 2.83.
MS (ESI): m/z = 471.09 [M + H]+ (100%).
9-(2-Methoxyphenyl)-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9d)
Yield: 74 mg (74%); pale yellow solid; mp 162–164 °C.
Anal. Calcd for C28H26N2O3S: C, 71.46; H, 5.57; N, 5.95. Found: C,
71.60; H, 5.48; N, 5.90.
IR (KBr): 1575, 1595, 1729, 2920 cm–1.
Pyranoquinoline and Phenanthrolinone Derivatives; General
Procedure
1H NMR (400 MHz, CDCl3): δ = 2.23 (s, 3 H), 3.56 (s, 3 H), 4.44
(dd, J = 4.8 Hz, 17.2 Hz, 1 H), 4.62 (dd, J = 5.2 Hz, 17.2 Hz, 1 H),
5.92 (t, J = 10.0 Hz, 1 H), 5.97 (t, J = 4.8 Hz, 1 H), 6.24 (d, J = 7.2
Hz, 1 H), 6.76 (t, J = 7.2 Hz, 1 H), 6.84 (d, J = 8.0 Hz, 1 H), 6.96–
7.02 (m, 3 H), 7.23–7.29 (m, 2 H), 7.45 (d, J = 7.6 Hz, 2 H), 8.07
(d, J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.4, 45.1, 55.2, 111.0, 114.7,
115.3, 116.6, 120.7, 127.6, 128.0, 128.1, 128.3, 129.2, 129.3, 129.5,
130.3, 133.0, 133.1, 136.6, 140.9, 143.6, 153.1, 155.6, 160.0.
Alkyne 7 (100 mg) was added to a vigorously stirred solution of
FeCl3 (1 equiv) in MeCN (2 mL) at r.t., and the resulting mixture
was stirred at 80 °C under an N2 atmosphere for 12 h. After comple-
tion of the reaction (monitored by TLC), the mixture was cooled and
extracted with CH2Cl2 (3 × 25 mL). The combined organic extract
was washed with brine (25 mL) and dried over Na2SO4. The solvent
was removed by distillation and the resulting crude residue was pu-
rified by filtration through a pad of silica gel (230–400 mesh, PE–
EtOAc) to give the pure cyclized product 9.
MS (ESI): m/z = 460.06 [M + H]+ (100%).
9-(4-Ethoxyphenyl)-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9a)
Yield: 76 mg (76%); pale yellow solid; mp 176–178 °C.
Anal. Calcd for C26H21NO5S: C, 67.96; H, 4.61; N, 3.05. Found: C,
67.79; H, 4.65; N, 3.11.
IR (KBr): 1510, 1609, 1734, 2970 cm–1.
9-[4-(Benzyloxy)phenyl]-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9e)
1H NMR (400 MHz, CDCl3): δ = 1.43 (t, J = 6.8 Hz, 3 H), 2.19 (s,
3 H), 4.02 (q, J = 6.8 Hz, 2 H), 4.47 (s, 2 H), 5.76 (t, J = 4.8 Hz, 1
H), 5.95 (d, J = 10.0 Hz, 1 H), 6.49 (s, 2 H), 6.72 (d, J = 7.6 Hz, 2
H), 6.96 (t, J = 6.8 Hz, 3 H), 7.35 (d, J = 8.0 Hz, 3 H), 8.08 (d,
J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 14.8, 21.4, 45.2, 63.5, 114.4,
114.6, 115.3, 117.2, 125.0, 127.5, 128.2, 129.0, 129.3, 130.7, 132.1,
133.7, 136.0, 136.7, 141.4, 143.7, 153.6, 158.7, 160.0.
Yield: 72 mg (72%); pale yellow solid; mp 184–186 °C.
IR (KBr): 1571, 1592, 1731, 2952 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.12 (s, 3 H), 4.46 (s, 2 H), 5.06
(s, 2 H), 5.76 (s, 1 H), 5.94 (t, J = 10.0 Hz, 1 H), 6.50 (s, 2 H), 6.75–
6.80 (m, 2 H), 6.92–6.97 (m, 3 H), 7.21–7.42 (m, 8 H), 8.07 (d,
J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.3, 45.2, 70.0, 114.6, 115.0,
115.3, 117.2, 125.1, 127.5, 128.2, 128.7, 128.9, 129.3, 130.7, 132.5,
133.7, 136.0, 136.5, 136.6, 141.3, 143.7, 153.6, 158.5, 159.9.
MS (ESI): m/z = 474.00 [M + H]+ (100%), 496.00 [M + Na]+ (66%).
Anal. Calcd for C27H23NO5S: C, 68.48; H, 4.90; N, 2.96. Found: C,
68.61; H, 4.94; N, 3.02.
MS (ESI): m/z = 536.08 [M + H]+ (100%).
Anal. Calcd for C32H25NO5S: C, 71.76; H, 4.70; N, 2.62. Found: C,
71.98; H, 4.65; N, 2.58.
9-(2-Ethoxyphenyl)-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9b)
Yield: 71 mg (71%); pale yellow solid; mp 178–180 °C.
9-[4-(Allyloxy)phenyl]-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9f)
Yield: 66 mg (66%); pale yellow solid; mp 120–122 °C.
IR (KBr): 1508, 1567, 1724, 2919 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.19 (s, 3 H), 4.47 (d, J = 4.8 Hz,
2 H), 4.53 (d, J = 4.8 Hz, 2 H), 5.33 (dd, J = 1.2 Hz, 10.4 Hz, 1 H),
5.44 (dd, J = 1.2 Hz, 16.8 Hz, 1 H), 5.77 (t, J = 4.8 Hz, 1 H), 5.95
(d, J = 10.0 Hz, 1 H), 6.02–6.06 (m, 1 H), 6.50 (d, J = 7.6 Hz, 2 H),
6.75 (d, J = 8.8 Hz, 2 H), 6.94–6.97 (m, 3 H), 7.30–7.35 (m, 3 H),
8.08 (d, J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.4, 45.2, 68.8, 114.6, 114.7,
115.3, 117.2, 118.1, 125.1, 127.4, 127.5, 128.2, 129.4, 130.1, 130.7,
132.3, 132.9, 133.7, 136.0, 136.6, 141.4, 143.8, 153.6, 158.3, 160.0.
IR (KBr): 1575, 1732, 2980 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.01 (t, J = 6.8 Hz, 3 H), 2.21 (s,
3 H), 3.72 (q, J = 7.6 Hz, 1 H), 3.87 (q, J = 7.6 Hz, 1 H), 4.49 (d,
J = 4.0 Hz, 2 H), 5.93 (t, J = 4.8 Hz, 2 H), 6.40 (d, J = 6.8 Hz, 1 H),
6.76–6.79 (m, 2 H), 6.99–7.06 (m, 3 H), 7.21–7.30 (m, 2 H), 7.49
(d, J = 7.6 Hz, 2 H), 8.06 (d, J = 9.2 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 14.4, 21.4, 45.0, 63.3, 111.8,
114.6, 115.6, 116.5, 120.6, 127.6, 127.8, 128.2, 129.2, 129.3, 129.4,
129.5, 130.2, 133.2, 133.5, 136.8, 141.0, 143.6, 152.9, 155.0, 160.1.
MS (ESI): m/z = 474.00 [M + H]+ (100%), 496.00 [M + Na]+ (66%).
Anal. Calcd for C27H23NO5S: C, 68.48; H, 4.90; N, 2.96. Found: C,
68.64; H, 4.85; N, 3.03.
MS (ESI): m/z = 486.09 [M + H]+ (100%).
9-(4-Isopropoxyphenyl)-7-tosyl-7,8-dihydro-3H-pyrano[3,2-
f]quinolin-3-one (9c)
Yield: 76 mg (76%); pale yellow solid; mp 160–162 °C.
Anal. Calcd for C28H23NO5S: C, 69.26; H, 4.77; N, 2.88. Found: C,
69.40; H, 4.71; N, 2.91.
IR (KBr): 1579, 1732, 2992 cm–1.
9-(4-Isopropoxyphenyl)-4-methyl-7-tosyl-7,8-dihydro-4,7-
phenanthrolin-3(4H)-one (9g)
1H NMR (400 MHz, CDCl3): δ = 1.35 (d, J = 6.0 Hz, 6 H), 2.18 (s,
3 H), 4.46 (d, J = 3.6 Hz, 2 H), 4.54 (quin, J = 6.0 Hz, 1 H), 5.76 (t,
J = 4.8 Hz, 1 H), 5.95 (t, J = 9.6 Hz, 1 H), 6.49 (d, J = 7.2 Hz, 2 H),
Yield: 75 mg (75%); pale yellow solid; mp 174–176 °C.
IR (KBr): 1508, 1563, 1660, 2973 cm–1.
Synthesis 2014, 46, 1413–1420
© Georg Thieme Verlag Stuttgart · New York

PAPER
Dihydropyridocoumarins and Phenanthrolinones
1419
1H NMR (400 MHz, CDCl3): δ = 1.34 (d, J = 6.0 Hz, 6 H), 2.14 (s,
3 H), 3.75 (s, 3 H), 4.45 (s, 2 H), 4.51 (quin, J = 6.0 Hz, 1 H), 5.75
(t, J = 5.2 Hz, 1 H), 6.24 (d, J = 10.0 Hz, 1 H), 6.47 (br s, 2 H), 6.67
(d, J = 8.0 Hz, 2 H), 6.92 (d, J = 8.0 Hz, 2 H), 7.06 (d, J = 10.0 Hz,
1 H), 7.35 (d, J = 8.0 Hz, 2 H), 7.43 (d, J = 9.2 Hz, 1 H), 8.13 (d,
J = 8.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 21.3, 22.0, 29.9, 45.3, 70.0,
114.7, 115.6, 117.0, 119.8, 124.7, 127.4, 128.1, 129.0, 129.28,
129.33, 132.2, 132.5, 136.1, 137.1, 137.2, 139.8, 143.5, 157.4,
161.6.
search Fellowship. We also thank the DST (New Delhi) for
providing a Bruker NMR spectrometer (400 MHz), a Perkin-Elmer
CHN analyzer, a UV/Vis spectrometer and a Perkin-Elmer FT-IR
spectrometer under the FIST program.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.SnoIufproi
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References
MS (ESI): m/z = 501.20 [M + H]+ (100%), 523.17 [M + Na]+ (33%).
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Anal. Calcd for C29H28N2O4S: C, 69.58; H, 5.64; N, 5.60. Found: C,
69.74; H, 5.65; N, 5.63.
9-(4-Ethoxyphenyl)-4-methyl-7-tosyl-7,8-dihydro-4,7-phenan-
throlin-3(4H)-one (9h)
Yield: 69 mg (69%); pale yellow gummy solid.
IR (KBr): 1510, 1606, 1651, 2249, 2982 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.42 (t, J = 6.8 Hz, 3 H), 2.15 (s,
3 H), 3.75 (s, 3 H), 4.01 (q, J = 6.8 Hz, 2 H), 4.44 (d, J = 5.2 Hz, 2
H), 5.76 (t, J = 5.2 Hz, 1 H), 6.23 (d, J = 10.0 Hz, 1 H), 6.48 (br s,
1 H), 6.68 (d, J = 8.0 Hz, 2 H), 6.92 (d, J = 8.0 Hz, 1 H), 7.05 (d,
J = 10.0 Hz, 1 H), 7.35 (d, J = 8.0 Hz, 2 H), 7.43 (d, J = 9.2 Hz, 1
H), 7.47–7.51 (m, 1 H), 7.55 (t, J = 8.0 Hz, 1 H), 8.13 (d, J = 9.2 Hz,
1 H).
13C NMR (100 MHz, CDCl3): δ = 14.8, 21.4, 29.9, 45.3, 63.5,
114.2, 114.7, 116.9, 119.8, 124.7, 127.4, 128.1, 129.0, 129.3, 132.2,
132.7, 136.1, 137.0, 137.2, 139.8, 143.5, 158.5, 161.5.
MS (ESI): m/z = 487.12 [M + H]+ (100%).
Anal. Calcd for C28H26N2O4S: C, 69.11; H, 5.39; N, 5.76. Found: C,
69.28; H, 5.45; N, 5.67.
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Macromolecules 1981, 14, 870. (c) Agrawal, A. K.;
Jenekhe, S. A. Macromolecules 1991, 24, 6806. (d) Jenekhe,
S. A.; Lu, L.; Alam, M. M. Macromolecules 2001, 34, 7315.
(e) Jegou, G.; Jenekhe, S. A. Macromolecules 2001, 34,
7926. (f) Lu, L.; Jenekhe, S. A. Macromolecules 2001, 34,
6249. (g) Zhang, X.; Shetty, A. S.; Jenekhe, S. A.
Macromolecules 2000, 33, 2069.
9-(4-Methoxyphenyl)-4-methyl-7-tosyl-7,8-dihydro-4,7-phen-
anthrolin-3(4H)-one (9i)
Yield: 63 mg (63%); pale yellow gummy solid.
IR (KBr): 1507, 1556, 1662, 2968 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.15 (s, 3 H), 3.75 (s, 3 H), 3.80
(s, 3 H), 4.45 (s, 2 H), 5.76 (s, 1 H), 6.23 (d, J = 9.6 Hz, 1 H), 6.49
(br s, 2 H), 6.69 (d, J = 7.2 Hz, 2 H), 6.92 (d, J = 7.2 Hz, 2 H), 7.05
(d, J = 8.8 Hz, 1 H), 7.35 (d, J = 7.2 Hz, 2 H), 7.43 (d, J = 8.4 Hz, 1
H), 8.13 (d, J = 8.4 Hz, 1 H).
MS (ESI): m/z = 473.19 [M + H]+ (100%).
Anal. Calcd for C27H24N2O4S: C, 68.62; H, 5.12; N, 5.93. Found: C,
68.48; H, 5.15; N, 5.99.
9-(4-Ethoxyphenyl)-4-ethyl-7-tosyl-7,8-dihydro-4,7-phenan-
throlin-3(4H)-one (9j)
Yield: 68 mg (68%); pale yellow gummy solid.
IR (KBr): 1510, 1552, 1660, 2973 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.21–1.31 (m, 3 H), 1.42 (t,
J = 7.2 Hz, 3 H), 2.15 (s, 3 H), 4.01 (d, J = 6.4 Hz, 2 H), 4.38 (d,
J = 6.8 Hz, 2 H), 4.44 (s, 2 H), 5.74 (s, 1 H), 6.22 (d, J = 9.6 Hz, 1
H), 6.49 (br s, 2 H), 6.68 (d, J = 7.2 Hz, 2 H), 6.92 (d, J = 7.2 Hz, 2
H), 7.06 (d, J = 10.0 Hz, 1 H), 7.34 (t, J = 7.2 Hz, 2 H), 7.43 (d,
J = 8.8 Hz, 1 H), 8.13 (d, J = 8.8 Hz, 1 H).
(8) (a) Saito, I.; Sando, S.; Nakatani, K. Bioorg. Med. Chem.
2001, 9, 2381. (b) He, C.; Lippard, S. J. J. Am. Chem. Soc.
2001, 40, 1414.
MS (ESI): m/z = 501.09 [M + H]+ (100%).
(9) (a) Murray, R. D. H.; Mendez, J.; Brown, S. A. The Natural
Coumarins: Occurrence, Chemistry and Biochemistry; John
Wiley & Sons: New York, 1982, 27. (b) Fylaktakidou, K. C.;
Hadjipavlou-Litina, D. J.; Litinas, K. E.; Nicolaides, D. N.
Curr. Pharm. Des. 2004, 10, 3813. (c) Zhang, W.; Pugh, G.
Tetrahedron Lett. 2001, 42, 5613.
Anal. Calcd for C29H28N2O4S: C, 69.58; H, 5.64; N, 5.60. Found: C,
69.78; H, 5.69; N, 5.69.
Acknowledgment
K.C.M. is thankful to UGC, (New Delhi) for an Emeritus Fellow-
ship, and S.P. is grateful to CSIR, (New Delhi) for a Senior Re-
(10) Wu, J.; Liao, Y.; Yang, Z. J. Org. Chem. 2001, 66, 3642.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 1413–1420

1420
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Synthesis 2014, 46, 1413–1420
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