Palladium-catalyzed synthesis of 4-arylcoumarins using triarylbismuth compounds as atom-Efficient multicoupling organometallic nucleophiles

Article abstract of DOI:10.1002/ejoc.201000134

Triarylbismuth compounds have been cross-coupled as atomefficient multicoupling organometallic nucleophiles with. 4bromo- and 4- (trifluoromethylsulfonyloxy)coumarins under palladium catalysis conditions. These reactions afforded an array of 4-arylcoumari

Full text of DOI:10.1002/ejoc.201000134

FULL PAPER
DOI: 10.1002/ejoc.201000134
Palladium-Catalyzed Synthesis of 4-Arylcoumarins Using Triarylbismuth
Compounds as Atom-Efficient Multicoupling Organometallic Nucleophiles
Maddali L. N. Rao,*[a] Varadhachari Venkatesh,[a] and Deepak N. Jadhav[a]
Keywords: Palladium / Cross-coupling / Bismuth / Oxygen heterocycles / Organometallic reactions
Triarylbismuth compounds have been cross-coupled as atom-
efficient multicoupling organometallic nucleophiles with 4-
bromo- and 4-(trifluoromethylsulfonyloxy)coumarins under
palladium catalysis conditions. These reactions afforded an
array of 4-arylcoumarins in high yields. The general palla-
dium protocol has been demonstrated to be efficient for the
coupling of both bromide and triflate derivatives of couma-
rins with triarylbismuth reagents.
with 1 equiv. of organometallic nucleophile under metal-
catalyzed conditions.
Introduction
Coumarin and its analogues exhibit several important
However, we favor coupling reactions with triarylbis-
biological activities such as anticancer, antiviral, anti-in- muth organometallic nucleophiles as these reagents can ef-
flammatory, anticoagulant, antioxidant, anti-HIV, and cen- ficiently couple with 3 equiv. of organic electrophiles.[7] Re-
tral nervous system activities.[1a–1g] In addition, these com- cent interest in organobismuth reagents is due to their po-
pounds are also known for their various photophysical ap- tential nontoxicity and novel reactivity in various applica-
plications.[1h–1j] Several procedures have been published in tions.[8,9] As a continuation of our efforts to develop triaryl-
the literature for the synthesis of various substituted cou- bismuth compounds as atom-efficient multicoupling orga-
marins.[2]
nometallic nucleophiles,[10] we have studied the cross-cou-
Transition-metal-catalyzed cross-coupling reactions of pling reactions of 4-bromo- and 4-(trifluoromethyl-
organometallic reagents are well known for the formation sulfonyloxy)coumarins with triarylbismuth compounds.
of carbon–carbon bonds. Reactions involving a variety of Herein, we report a general and efficient palladium-cata-
organometallic nucleophiles are routinely used to synthesize lyzed protocol for the facile synthesis of an array of 4-aryl-
a plethora of molecules in synthetic organic chemistry[3,4] coumarins using triarylbismuth compounds as atom-
and various functionalized 4-arylcoumarins are easily ac- efficient multicoupling nucleophiles.
cessible under metal-catalyzed coupling conditions.[5] Or-
ganic electrophiles such as triflate,[5a–5f] bromo,[5d,5f] tosyla-
te,[5d,5g–5q] and phosphonate[5r] derivatives of coumarins
Results and Discussion
have been successfully coupled with, for example, or-
ganoboron, -tin, -zinc, and -indium organometallic reagents
to synthesize 4-arylcoumarins under metal-catalyzed condi-
tions. The coupling reactions of 4-trimethylstannylcouma-
rins with aryl iodides or triflates under palladium-catalyzed
conditions have also been reported for the preparation of
4-arylcoumarins.[5s] A few other methods involving ring-
closing metathesis or metal-catalyzed cyclization reactions
are also useful for the synthesis of coumarin scaffolds.[6] In
particular, various organometallic reagents exhibit varied
reactivity in these cross-coupling reactions. Moreover, these
reactions provide only 1 equiv. of 4-arylcoumarin product
First, the bromo (1a–5a) and triflate (1b–4b) derivatives
of coumarin required for the coupling reactions were pre-
pared following literature procedures starting from the cor-
responding 4-hydroxycoumarins (Figure 1).[5a,11] To estab-
lish efficient cross-coupling conditions, initial experiments
were carried out with 4-bromocoumarin (1a) and tri-
phenylbismuth under different coupling conditions
(Table 1). The reaction in the presence of [PdCl2(PPh3)2] as
catalyst and K3PO4 as base in N,N-dimethylacetamide
(DMA) at room temperature furnished cross-coupling
product 4-phenyl-2H-1-benzopyran-2-one (1c) in 39% yield
(Table 1, entry 1) along with biphenyl and unreacted 4-bro-
mocoumarin. The formation of homocoupling product bi-
phenyl from triphenylbismuth is well known under palla-
dium-catalyzed conditions.[9e] At elevated temperatures, im-
proved conversions to 1c were obtained (Table 1, entries 2
and 3).
[a] Department of Chemistry, Indian Institute of Technology
Kanpur,
Kanpur 208 016, India
Fax: +91-512-259-7532
E-mail: maddali@iitk.ac.in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201000134.
Eur. J. Org. Chem. 2010, 3945–3955
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3945

M. L. N. Rao, V. Venkatesh, D. N. Jadhav
FULL PAPER
The coupling reaction performed over 1 h provided a rel-
atively low yield of the product (Table 1, entry 14). A few
control reactions were next carried out to gain an under-
standing of the effective role of the catalyst and base. The
reaction without base afforded only a moderate yield of the
product (Table 1, entry 15), whereas the reaction performed
without the catalyst led to only 4% conversion to the prod-
uct (Table 1, entry 16). From the above screening it is clear
that the cross-coupling reaction is dependent on the nature
of the solvent, base, and catalyst precursor as well as tem-
perature. In all these screening reactions biphenyl was
formed as a side-product, the amount varying with respect
to the yield of the product. Overall, the catalytic protocol
using [PdCl2(PPh3)2] as catalyst with K3PO4 as base in
DMA at 90 °C was found to be the most effective combina-
tion for obtaining an excellent yield of cross-coupled prod-
uct (Table 1, entry 8). Although other carbonate bases were
found to be equally efficient, we continued our studies with
K3PO4 as base.
Figure 1. 4-Bromo and triflate derivatives of coumarins.
Table 1. Screening conditions.[a]
Having established an efficient palladium protocol for
the coupling of 4-bromocoumarin, it was of interest to
study the reactivity of 4-(trifluoromethylsulfonyloxy)cou-
marin derivatives as these compounds are also potential
substrates for coupling reactions and can easily be prepared
from the corresponding 4-hydroxycoumarin compounds.
Thus, 4-(trifluoromethylsulfonyloxy)coumarin (1b) was sub-
jected to cross-coupling with triphenylbismuth under the
optimized protocol developed for 4-bromocoumarin
(Scheme 1). The coupling reaction of 1b with triphenylbis-
muth proceeded smoothly to deliver the desired product 1c
in 92% isolated yield. This is interesting from the point of
view that both 4-bromo- and 4-(trifluoromethylsulfonyloxy)-
coumarins can be cross-coupled with triphenylbismuth un-
der the same conditions to furnish excellent yields of 4-
phenyl-2H-1-benzopyran-2-one (1c) in an efficient manner.
Entry
Catalyst
Base
[equiv.]
Solvent
Temp.
[°C]
Yield[b,c,d]
[%]
1
2
3
4
5
6
7
8
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
[PdCl2(PhCN)2]
[PdCl2(PPh3)2]
[PdCl2(PPh3)2]
no catalyst
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
DMA
DMA
DMA
NMP
r.t.
60
80
90
90
90
90
90
90
90
90
90
90
90
90
90
39
67
81
69
CH3CN
(47)
(19)
(26)
98
84
88
97
83
(43)
74[e]
69
K3PO4 1,4-dioxane
K3PO4
K3PO4
Na2CO3
K2CO3
Cs2CO3
CsF
K3PO4
K3PO4
No base
K3PO4
DME
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
9
10
11
12
13
14
15
16
(4)
[a] Reagents and conditions: 4-bromocoumarin (185.6 mg,
0.825 mmol, 3.3 equiv.), BiPh3 (110 mg, 0.25 mmol, 1.0 equiv.), cat-
alyst (0.0225 mmol, 0.09 equiv.), base (1 equiv.), and solvent
(3 mL). [b] Isolated yields. [c] GC conversion given in parentheses.
[d] Homocoupling biphenyl from triphenylbismuth was formed in
all the reactions in minor amounts. The amount is more in the
absence of the cross-coupling product. [e] Reaction time 1 h.
In an effort to further increase product formation, the
reaction was screened in different solvents (Table 1, en-
tries 4–8): DMA was found to be an effective solvent for
obtaining a high yield of the product 1c (Table 1, entry 8).
Scheme 1. Cross-coupling reaction of 1b with triphenylbismuth.
Encouraged by the observed facile reactivity of both the
Other solvents such as N-methyl-2-pyrrolidinone (NMP) bromo and triflate derivatives of coumarin under the opti-
and acetonitrile provided moderate conversions, whereas mized protocol it was of interest to expand the scope of this
1,4-dioxane and 1,2-dimethoxyethane (DME) afforded method. The coupling reactions of electronically divergent
poor conversions. Encouraged by the high coupling conver- triarylbismuth compounds were investigated with 4-bromo-
sion obtained in DMA with K3PO4 as base (Table 1, en- and 4-(trifluoromethylsulfonyloxy)coumarins and the re-
try 8), we next screened different bases. Interestingly, bases sults are summarized in Table 2. The reactivity of the triar-
such as Na2CO3, K2CO3, Cs2CO3, and CsF also furnished ylbismuth compounds was generally found to be excellent
high yields of the product in DMA (Table 1, entries 9–12). giving the substituted 4-arylcoumarins in high yields. Both
Additional screening with different catalytic precursors did electron-rich and -deficient triarylbismuth compounds par-
not result in good conversions under similar conditions ticipated efficiently in multicoupling reactions with 3 equiv.
(Table 1, entry 13).
of both 4-bromo- and 4-(trifluoromethylsulfonyloxy)cou-
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Eur. J. Org. Chem. 2010, 3945–3955

Palladium-Catalyzed Synthesis of 4-Arylcoumarins
marins under the optimized conditions. Note that the cou- coumarins with different triarylbismuth compounds under
pling reactions of triarylbismuth compounds are equally the established conditions (Table 3). All these coumarins
fast with both 4-bromo- and 4-(trifluoromethylsulfonyl- smoothly underwent cross-coupling reactions to furnish
oxy)coumarins furnishing three aryl couplings in a short variously functionalized 4-arylcoumarins in excellent yields.
reaction time.
These reactions demonstrate the generality and versatility
of the coupling protocol with both bromo and triflate deriv-
atives of coumarins. This study has also revealed the high
coupling reactivity of triarylbismuth compounds with
3 equiv. of 4-bromo- and 4-(trifluoromethylsulfonyloxy)-
coumarins. Notably, the bromide and triflate derivatives of
coumarins were found to be similarly reactive, furnishing
excellent yields of the products with different triarylbismuth
compounds under the established protocol. Thus, this
method is a general protocol for the efficient coupling of
both bromo and triflate derivatives of coumarins with tri-
arylbismuth reagents.
Table 2. Cross-coupling reactions with different triarylbismuth
compounds[a–c]
.
The reactions of 4-bromo- and 4-(trifluoromethylsulfon-
yloxy)coumarins with triarylbismuth compounds under the
established conditions are completed in 2 h giving high
yields of 4-arylcoumarins through three C–C coupling reac-
tions. However, the majority of coupling reactions reported
in the literature for the synthesis of 4-arylcoumarins using
triflate, bromide, tosylate, and phosphonate derivatives of
coumarins involve longer reaction times at a variety of tem-
peratures even for the formation of 1 equiv. of product.[5]
Although the coupling reactivity of triarylindiums with 4-
(tosyloxy)coumarins was reported to be fast at room tem-
perature under palladium-catalyzed conditions, the triaryl-
indiums are involved in only one C–C coupling reaction.[5o]
Our initial study of the reaction of 4-tosyloxycoumarin with
triphenylbismuth under the present coupling conditions
provided only 9% of 4-phenylcoumarin. Thus, the protocol
in hand is not appropriate for the coupling of 4-tosyloxy-
coumarin with triarylbismuth compounds and thus further
study is required to find suitable conditions.
The catalytic cycle of these coupling reactions is expected
to follow the general pathway known[3e] for this type of cou-
pling reaction (Scheme 2). The initial oxidative addition of
4-Br- or 4-OTf-substituted coumarin to Pd0 forms interme-
diate A. This intermediate then undergoes transmetalation
with triarylbismuth to give PdII intermediate B, which upon
reductive elimination delivers 4-arylcoumarin, regenerating
Pd0 and enabling the catalytic cycle to continue. The added
base is expected to activate the Ar–Bi bond during the
transmetalation step for transfer of the aryl group. Further-
more, successive involvement of di- or monoarylbismuth in
the transmetalation step is likely for the atom-efficient utili-
zation of all three aryl groups from the bismuth reagent.
Alternatively, regeneration of triarylbismuth compounds in
situ by disproportionation of mono- or diarylbismuth com-
pounds is another possibility for the effective participation
of the three aryl groups from the triarylbismuth compounds
during the transmetalation step.[9e] The efficient coupling of
3 equiv. of both bromide and triflate derivatives of couma-
rins with triarylbismuth compounds furnishing very high
yields of 4-arylcoumarins proves the effective transfer of all
[a] Reagents and conditions: 4-bromo- or 4-(trifluoromethylsulfon-
yloxy)coumarin (0.825 mmol, 3.3 equiv.), BiAr3 (0.25 mmol,
1.0 equiv.), [PdCl2(PPh3)2] (0.0225 mmol, 0.09 equiv.), K3PO4
(0.25 mmol, 1.0 equiv.), and DMA (3 mL), 90 °C, 2 h. [b] Isolated
yields were calculated on the basis of all three aryl groups of the
triarylbismuth compounds participating in the coupling reactions.
Thus, 0.75 mmol of product corresponds to a 100% yield. [c]
Homocoupling biaryls were formed in all the reactions in minor
amounts.
Furthermore, we also studied the reactivity of various three groups from triarylbismuth compounds under the
substituted 4-bromo- and 4-(trifluoromethylsulfonyloxy)- coupling conditions.
Eur. J. Org. Chem. 2010, 3945–3955
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3947

M. L. N. Rao, V. Venkatesh, D. N. Jadhav
FULL PAPER
Table 3. Coupling reactions of functionalized 4-bromo- and 4-(trifluoromethylsulfonyloxy)coumarins with triarylbismuth compounds.[a–c]
[a] Reagents and conditions: functionalized 4-bromo- or 4-(trifluoromethylsulfonyloxy)coumarin (0.825 mmol, 3.3 equiv.), BiAr3
(0.25 mmol, 1.0 equiv.), [PdCl2(PPh3)2] (0.0225 mmol, 0.09 equiv.), K3PO4 (0.25 mmol, 1.0 equiv.), and DMA (3 mL), 90 °C, 2 h. [b]
Isolated yields were calculated on the basis on the basis of all three aryl groups of the triarylbismuth compounds participating in the
coupling reactions. Thus, 0.75 mmol of the product corresponds to a 100% yield. [c] Homocoupling biaryls were formed in all the
reactions in minor amounts.
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Palladium-Catalyzed Synthesis of 4-Arylcoumarins
Spectral Data for Coumarins 1a–5a and 1b–4b
4-Bromo-2H-chromen-2-one[11a] (1a): Colorless solid (76%, 2.11 g);
m.p. 75–77 °C. 1H NMR (500 MHz, CDC13): δ = 6.84 (s, 1 H,
CHalkenyl), 7.30–7.35 (m, 2 H, CHar), 7.57 (t, J = 7.4 Hz, 1 H,
CHar), 7.82 (d, J = 8.0 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 117.0, 119.0, 119.6, 125.0, 128.1, 133.2, 141.5, 152.5,
158.7 ppm. IR: ν
= 1717, 1599, 1172, 915, 841, 766 cm–1.
˜
max
HRMS (ES+): calcd. for C9H6BrO2 [M + H]+ 224.9551, 226.9531;
found 224.9556, 226.9534.
4-Bromo-6-methyl-2H-chromen-2-one (2a): Colorless solid (72%,
1
1.93 g); m.p. 78–80 °C. H NMR (500 MHz, CDC13): δ = 2.42 (s,
3 H, CH3), 6.81 (s, 1 H, CHalkenyl), 7.18–7.21 (m, 1 H, CHar), 7.36
(d, J = 8.0 Hz, 1 H, CHar), 7.58 (s, 1 H, CHar) ppm. 13C NMR
(125 MHz, CDC13): δ = 20.9, 116.8, 118.6, 119.5, 127.7, 134.2,
Scheme 2. Proposed catalytic cycle for the coupling reactions.
134.9, 141.5, 150.7, 159.0 ppm. IR: ν
= 3073, 2919, 1715, 1562,
˜
max
1341, 1173, 930, 851, 602 cm–1. HRMS (ES+): calcd. for
C10H8BrO2 [M
240.9687.
+
H]+ 238.9708, 240.9687; found 238.9709,
Conclusions
The palladium-catalyzed cross-coupling reactions of 4-
bromo- and 4-(trifluoromethylsulfonyloxy)coumarins with
triarylbismuth compounds have been investigated. The re-
actions demonstrate excellent reactivity under the estab-
lished general catalytic conditions furnishing 4-arylcoumar-
ins in excellent yields. Triarylbismuth compounds serve as
atom-efficient multicoupling organometallic nucleophiles
reacting efficiently with 3 equiv. of either 4-bromo- or 4-
(trifluoromethylsulfonyloxy)coumarins to furnish 3 equiv.
of 4-arylcoumarins. The reactions with triarylbismuth com-
pounds as multicoupling organometallic nucleophiles pro-
ceeded smoothly in short reaction times to afford excellent
yields of an array of functionalized 4-arylcoumarins.
4-Bromo-7-methyl-2H-chromen-2-one (3a): Pale-yellow solid (75%,
2.01 g); m.p. 124–126 °C. H NMR (500 MHz, CDC13): δ = 2.44
1
(s, 3 H, CH3), 6.50 (s, 1 H, CHalkenyl), 7.14 (d, J = 9.1 Hz, 2 H,
CHar), 7.69 (d, J = 8.0 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 21.8, 114.3, 115.7, 117.1, 125.2, 126.0, 144.9, 149.8,
153.1, 159.4 ppm. IR: νmax = 3064, 1739, 1351, 1137, 859, 786 cm–1.
˜
HRMS (EI+): calcd. for C10H7BrO2 [M]+ 237.9629, 239.9609;
found 237.9629, 239.9611.
4-Bromo-5,7-dimethyl-2H-chromen-2-one (4a): Pale-yellow solid
(67%, 1.78 g); m.p. 125–127 °C. 1H NMR (500 MHz, CDC13): δ =
2.36 (s, 3 H, CH3), 2.84 (s, 3 H, CH3), 6.46 (s, 1 H, CHalkenyl),
6.78 (s, 1 H, CHar), 7.01 (s, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 21.3, 24.5, 115.7, 116.3, 120.4, 130.5, 137.4, 139.7,
143.4, 150.5, 154.1, 158.6 ppm. IR: ν
= 2921, 1722, 1586, 1381,
˜
max
882, 844 cm–1. HRMS (ES+): calcd. for C11H10BrO2 [M + H]+
252.9864, 254.9844; found 252.9866, 254.9838.
1-Bromo-3H-benzo[f]chromen-3-one (5a): Pale-yellow solid (70%,
1.81 g); m.p. 126–128 °C. H NMR (500 MHz, CDC13): δ = 6.91
Experimental Section
1
(s, 1 H, CHalkenyl), 7.34–7.38 (m, 1 H, CHar), 7.51 (t, J = 7.4 Hz, 1
H, CHar), 7.59–7.62 (m, 1 H, CHar), 7.82 (d, J = 8.0 Hz, 1 H,
CHar), 7.94 (d, J = 8.5 Hz, 1 H, CHar), 9.47 (d, J = 8.6 Hz, 1 H,
CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 117.2, 117.3, 121.2,
124.6, 126.2, 127.8, 129.1, 129.4, 131.2, 135.2, 135.3, 138.6, 153.9,
General: All reactions were carried out under nitrogen in oven-
dried apparatus. All solvents were distilled following standard dry-
ing procedures. Commercially obtained materials were used with-
out further purification. The bromo (1a–5a) and triflate (1b–4b)
derivatives of coumarin were prepared following literature pro-
cedures starting from the corresponding 4-hydroxycoumarins.[5a,11]
Triarylbismuth compounds were synthesized following literature
procedures.[8a] GC analysis was carried out with a Perkin–Elmer
Clarus-500 gas chromatograph. Analytical thin layer chromatog-
raphy was performed on glass plates precoated with silica gel
GF254 (Spectrochem, Mumbai) and the product spots were visual-
ized with ultraviolet light. Column chromatography was performed
with 60–120 silica gel (Acme, Mumbai) using ethyl acetate/petro-
leum ether as the eluent. Product purity was analyzed with a
Waters-2996 HPLC chromatograph using 2-propanol/hexane as
eluent and a Chiralcel OD-H column. The 1H and 13C NMR spec-
tra were recorded with JEOL Lambda (400 MHz) and Delta
(500 MHz) NMR spectrometers in CDCl3. The chemical shifts (δ)
for protons and carbon atoms are quoted in parts per million
(ppm). The coupling constants (J) are expressed in hertz (Hz). The
IR spectra were recorded with a Bruker Vector 22 FT-IR spectrom-
eter and are reported in wavenumbers (cm–1). High-resolution mass
spectra (HRMS) were recorded with Waters HAB213 and CAB155
micromass spectrometers using the electrospray (ES) and elec-
troionization (EI) techniques.
158.2 ppm. IR: ν
= 1721, 1537, 848, 819, 754 cm–1. HRMS
˜
max
(ES+): calcd. for C13H8BrO2 [M + H]+ 274.9708, 276.9687; found
274.9708, 276.9663.
2-Oxo-2H-chromen-4-yl Trifluoromethanesulfonate[5a] (1b): Pale-
yellow solid (81%, 2.94 g) m.p. 54–56 °C. 1H NMR (500 MHz,
CDC13): δ = 6.49 (s, 1 H, CHalkenyl), 7.38–7.44 (m, 2 H, CHar),
7.66–7.69 (m, 2 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ =
105.9, 113.9, 117.4, 122.6, 125.3, 134.2, 153.5, 157.2, 159.6 ppm.
IR: νmax = 3085, 1738, 1634, 1430, 1374, 1215, 1046, 874, 765 cm–1.
˜
HRMS (ES+): calcd. for C10H6F3O5S [M + H]+ 294.9888; found
294.9885.
6-Methyl-2-oxo-2H-chromen-4-yl
Trifluoromethanesulfonate[11b]
(2b): Pale-yellow solid (78%, 2.73 g); m.p. 84–87 °C. 1H NMR
(500 MHz, CDC13): δ = 2.40 (s, 3 H, CH3), 6.41 (s, 1 H, CHalkenyl),
7.20–7.26 (m, 1 H, CHar), 7.39–7.43 (m, 2 H, CHar) ppm. 13C
NMR (125 MHz, CDC13): δ = 21.0, 105.7, 113.6, 117.2, 122.1,
135.3, 151.7, 157.2, 159.8 ppm. IR: ν
= 3080, 2928, 1739, 1637,
˜
max
1574, 1417, 1212, 1135, 840 cm–1. HRMS (ES+): calcd. for
C11H8F3O5S [M + H]+ 309.0045; found 309.0045.
Eur. J. Org. Chem. 2010, 3945–3955
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M. L. N. Rao, V. Venkatesh, D. N. Jadhav
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5,7-Dimethyl-2-oxo-2H-chromen-4-yl
Trifluoromethanesulfonate
7.31–7.40 (m, 5 H, CHar), 7.52–7.55 (m, 2 H, CHar) ppm. 13C
NMR (125 MHz, CDC13): δ = 21.4, 114.9, 117.4, 119.1, 124.2,
(3b): Pale-yellow solid (75%, 2.55 g); m.p. 115–117 °C. 1H NMR
(500 MHz, CDC13): δ = 2.37 (s, 3 H, CH3), 2.78 (s, 3 H, CH3), 127.1, 128.5, 129.6, 131.9, 132.3, 140.0, 154.2, 155.8, 161.0 ppm.
6.46 (s, 1 H, CHalkenyl), 6.91 (s, 1 H, CHar), 7.01 (s, 1 H, CHar) ppm. IR: νmax = 2920, 1728, 1605, 1448, 1367, 1183, 930, 819, 708 cm–1.
˜
13C NMR (125 MHz, CDC13): δ = 21.3, 24.1, 114.1, 114.2, 115.7, HRMS (ES+): calcd. for C16H13O2 [M + H]+ 237.0916; found
116.2, 117.5, 125.4, 130.3, 137.1, 143.6, 150.4, 154.7, 159.0 ppm.
237.0919.
IR: ν
= 3064, 2918, 1722, 1547, 1148, 874 cm–1. HRMS (ES+):
˜
max
4-(m-Tolyl)-2H-chromen-2-one[12a] (3c): Colorless solid (96%,
170.1 mg); m.p. 69–71 °C. H NMR (500 MHz, CDC13): δ = 2.45
calcd. for C12H10F3O5S [M + H]+ 323.0201; found 323.0206.
1
3-Oxo-3H-benzo[f]chromen-1-yl Trifluoromethanesulfonate (4b):
Pale-yellow solid (79%, 2.56 g); m.p. 113–115 °C. 1H NMR
(500 MHz, CDC13): δ = 6.66 (s, 1 H, CHalkenyl), 7.42 (d, J = 8.8 Hz,
1 H, CHar), 7.56–7.59 (m, 1 H, CHar), 7.65–7.68 (m, 1 H, CHar),
7.88 (d, J = 8.0 Hz, 1 H, CHar), 8.00 (d, J = 8.8 Hz, 1 H, CHar),
9.38 (d, J = 9.2 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 111.5, 116.7, 117.3, 124.8, 126.2, 128.4, 128.9, 129.5,
(s, 3 H, CH3), 6.37 (s, 1 H, CHalkenyl), 7.24 (t, J = 8.2 Hz, 3 H,
CHar), 7.33 (d, J = 7.3 Hz, 1 H, CHar), 7.40 (d, J = 7.8 Hz, 2 H,
CHar), 7.50–7.57 (m, 2 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 21.4, 115.0, 117.2, 119.0, 124.0, 125.5, 127.0, 128.6,
128.9, 130.3, 131.8, 135.1, 138.7, 154.1, 155.8, 160.7 ppm. IR: ν
˜
max
= 2919, 1728, 1604, 1448, 1367, 1251, 1179, 935, 868, 751 cm–1.
HRMS (ES+): calcd. for C16H13O3 [M + H]+ 237.0916; found
237.0916.
131.2, 135.3, 150.0, 154.6, 158.6 ppm. IR: νmax = 3077, 1724, 1543,
˜
1515, 782, 749 cm–1. HRMS (ES+): calcd. for C14H8F3O5S [M +
H]+ 345.0045; found 345.0049.
4-(4-Methoxyphenyl)-2H-chromen-2-one[12a] (4c): Colorless solid
1
(97%, 183.5 mg); m.p. 116–118 °C. H NMR (500 MHz, CDC13):
Representative Procedure for the Cross-Coupling Reactions of 4-
Bromocoumarins with Triarylbismuth Compounds: An oven-dried
Schlenk tube under nitrogen was charged with 4-bromocoumarin
(185.6 mg, 0.825 mmol, 3.3 equiv.), BiPh3 (110 mg, 0.25 mmol,
1 equiv.), K3PO4 (53.1 mg, 0.25 mmol, 1 equiv.), [PdCl2(PPh3)2]
(15.8 mg, 0.0225 mmol, 0.09 equiv.), and dry DMA and the mix-
ture was stirred at 90 °C for 2 h. Then the contents were cooled to
room temperature and extracted with ethyl acetate, washed with
dilute HCl (5 mL), water (5 mL), and brine (5 mLϫ2), and dried
with anhydrous MgSO4. The solvent was concentrated on a rotary
evaporator to give the crude product which by column chromatog-
raphy afforded the desired product 1c as a colorless solid (98%,
163.3 mg). The isolated yield was calculated on the basis that all
three aryl groups of triphenylbismuth participate in the coupling
reactions. Thus, 0.75 mmol of the product corresponds to a 100%
yield.
δ = 3.87 (s, 3 H, OCH3), 6.33 (s, 1 H, CHalkenyl), 7.03 (d, J = 8.6 Hz,
1 H, CHar), 7.20–7.25 (m, 2 H, CHar), 7.39 (t, J = 8.4 Hz, 3 H,
CHar), 7.51–7.55 (m, 2 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 55.5, 114.4, 114.6, 117.4, 119.2, 124.1, 127.1, 127.5,
130.0, 131.9, 154.3, 155.4, 160.9, 161.0 ppm. IR: νmax = 2932, 2838,
˜
1726, 1605, 1510, 1368, 1247, 1180, 1030, 930, 867, 772 cm–1.
HRMS (ES+): calcd. for C16H13O3 [M + H]+ 253.0865; found
253.0866.
4-(3-Methoxyphenyl)-2H-chromen-2-one[12b] (5c): Pale-yellow solid
1
(94%, 177.8 mg); m.p. 134–136 °C. H NMR (500 MHz, CDC13):
δ = 3.85 (s, 3 H, OCH3), 6.37 (s, 1 H, CHalkenyl), 7.01–7.05 (m, 2
H, CHar), 7.21–7.25 (m, 1 H, CHar), 7.37–7.44 (m, 2 H, CHar),
7.51–7.56 (m, 2 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ =
55.5, 114.1, 115.1, 115.2, 117.4, 119.0, 120.8, 124.2, 127.1, 130.1,
132.0, 136.5, 154.2, 155.6, 159.8, 160.8 ppm. IR: νmax = 3070, 2938,
˜
2837, 1728, 1603, 1449, 1181, 1037, 935, 862, 752, 716 cm–1. HRMS
(ES+): calcd. for C16H13O3 [M + H]+ 253.0865; found 253.0867.
Representative Procedure for the Cross-Coupling Reactions of 4-(Tri-
fluoromethanesulfonyloxy)coumarins with Triarylbismuth Com-
pounds: An oven-dried Schlenk tube under nitrogen was charged
4-(4-Ethoxyphenyl)-2H-chromen-2-one (6c): Colorless solid (90%,
1
179.7 mg); m.p. 94–96 °C. H NMR (400 MHz, CDC13): δ = 1.47
with
4-(trifluoromethylsulfonyloxy)coumarin
(242.7 mg,
(t, J = 7.0 Hz, 3 H, CH3), 4.12 (q, J = 7.0 Hz, 2 H, OCH2), 6.35
(s, 1 H, CHalkenyl), 7.03 (d, J = 8.5 Hz, 2 H, CHar), 7.22–7.26 (m,
1 H, CHar), 7.36 (s, 1 H, CHar), 7.40 (d, J = 8.5 Hz, 2 H, CHar),
7.52–7.58 (m, 2 H, CHar) ppm. 13C NMR (100 MHz, CDC13): δ =
14.7, 63.6, 114.5, 114.7, 117.3, 119.1, 124.0, 127.0, 127.2, 128.2,
0.825 mmol, 3.3 equiv.), BiPh3 (110 mg, 0.25 mmol, 1 equiv.),
K3PO4 (53.1 mg, 0.25 mmol, 1 equiv.), [PdCl2(PPh3)2] (15.8 mg,
0.0225 mmol, 0.09 equiv.), and dry DMA and the mixture was
stirred at 90 °C for 2 h. Then the contents were cooled to room
temperature and extracted with ethyl acetate, washed with dilute
HCl (5 mL), water (5 mL), and brine (5 mLϫ2), and dried with
anhydrous MgSO4. Then the solvent was concentrated on a rotary
evaporator to give the crude product, which, on column
chromatography, afforded the desired product 1c as a colorless so-
lid (92%, 153.2 mg). The isolated yield was calculated on the basis
that all three aryl groups of triphenylbismuth participate in the
coupling reactions. Thus, 0.75 mmol of the product corresponds to
a 100% yield.
129.9, 131.7, 154.2, 155.3, 160.2, 160.9 ppm. IR: νmax = 3071, 2979,
˜
2930, 1727, 1607, 1510, 1368, 1245, 1180, 1117, 1044, 929, 839,
752 cm–1. HRMS (ES+): calcd. for C17H15O3 [M + H]+ 267.1021;
found 267.1020.
4-(4-Isopropoxyphenyl)-2H-chromen-2-one (7c): Colorless solid
1
(93%, 195.5 mg); m.p. 123–125 °C. H NMR (400 MHz, CDC13):
δ = 1.40 [d, J = 5.8 Hz, 6 H, C(CH3)2], 4.61–4.67 (m, 1 H, OCH),
6.35 (s, 1 H, CHalkenyl), 7.02 (d, J = 8.8 Hz, 2 H, CHar), 7.22–
7.26 (m, 1 H, CHar), 7.35–7.41 (m, 3 H, CHar), 7.52–7.60 (m, 2 H,
CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 21.9, 70.0, 114.4,
115.8, 117.3, 119.1, 124.0, 127.0, 129.9, 131.7, 154.2, 155.3, 159.2,
4-Phenyl-2H-chromen-2-one[5g] (1c): Colorless solid (98%,
1
163.3 mg); m.p. 74–76 °C. H NMR (500 MHz, CDC13): δ = 6.37
(s, 1 H, CHalkenyl), 7.20–7.25 (m, 1 H, CHar), 7.39–7.56 (m, 8 H,
CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 115.2, 117.4, 119.0,
124.2, 127.1, 128.5, 129.7, 132.0, 135.2, 154.2, 155.7, 160.8 ppm.
160.9 ppm. IR: ν
= 2976, 2923, 1725, 1605, 1368, 1244, 1182,
˜
max
1118, 930, 814 cm–1. HRMS (ES+): calcd. for C19H17O3 [M + H]+
IR: ν
= 1723, 1605, 1447, 1369, 1181, 937, 867, 816, 777 cm–1.
281.1178; found 281.1175.
˜
max
HRMS (ES+): calcd. for C15H11O2 [M + H]+ 223.0759; found
4-(4-Butoxyphenyl)-2H-chromen-2-one[12c] (8c): Pale-yellow solid
223.0759.
1
(91%, 200.8 mg); m.p. 52–54 °C. H NMR (400 MHz, CDC13): δ
4-(p-Tolyl)-2H-chromen-2-one[12a] (2c): Colorless solid (95%, = 1.01 (t, J = 7.3 Hz, 3 H, CH3), 1.49–1.62 (m, 2 H, CH2), 1.79–
1
168.3 mg); m.p. 94–96 °C. H NMR (500 MHz, CDC13): δ = 2.44 1.86 (m, 2 H, CH2), 4.05 (t, J = 6.6 Hz, 2 H, OCH2), 6.35 (s, 1 H,
(s, 3 H, CH3), 6.35 (s, 1 H, CHalkenyl), 7.20–7.25 (m, 1 H, CHar), CHalkenyl), 7.03 (d, J = 8.7 Hz, 2 H, CHar), 7.21–7.26 (m, 1 H,
3950
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 3945–3955

Palladium-Catalyzed Synthesis of 4-Arylcoumarins
CHar), 7.39–7.41 (d, J = 8.5 Hz, 3 H, CHar), 7.52–7.58 (m, 2 H,
CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 13.8, 19.2, 31.2,
67.8, 114.5, 114.7, 117.3, 119.1, 124.0, 127.0, 127.1, 129.8, 131.7,
1331, 1163, 1114, 944, 810 cm–1. HRMS (ES+): calcd. for
C16H10F3O2 [M + H]+ 291.0633; found 291.0636.
6-Methyl-4-phenyl-2H-chromen-2-one[6h] (15c): Colorless solid
154.2, 155.3, 160.4 ppm. IR: ν
= 2958, 2933, 2872, 1727, 1606,
˜
max
1
(97%, 171.9 mg); m.p. 114–116 °C. H NMR (400 MHz, CDC13):
1510, 1368, 1245, 1179, 1117, 929, 837, 753 cm–1. HRMS (ES+):
calcd. for C19H19O3 [M + H]+ 295.1334; found 295.1333.
δ = 2.32 (s, 3 H, CH3), 6.34 (s, 1 H, CHalkenyl), 7.24–7.35 (m, 3 H,
CHar), 7.42–7.45 (m, 2 H, CHar), 7.52 (t, J = 3.8 Hz, 3 H,
4-(4-sec-Butoxyphenyl)-2H-chromen-2-one (9c): Pale-yellow solid CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 20.9, 115.1, 117.0,
1
(94%, 207.5 mg); m.p. 92–94 °C. H NMR (400 MHz, CDC13): δ 118.6, 126.6, 128.3, 128.8, 129.5, 132.8, 133.8, 135.3, 152.3, 155.5,
= 1.02 (t, J = 7.3 Hz, 3 H, CH3), 1.35 (d, J = 5.6 Hz, 3 H, CH3),
1.64–1.85 (m, 2 H, CH2), 4.36–4.43 (m, 1 H, OCH), 6.35 (s, 1 H,
CHalkenyl), 7.01 (d, J = 8.5 Hz, 2 H, CHar), 7.22–7.26 (m, 1 H,
CHar), 7.39 (dd, J = 1.9, 8.6 Hz, 3 H, CHar), 7.52–7.60 (m, 2 H,
CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 9.7, 19.1, 29.1, 75.1,
114.4, 114.5, 115.8, 117.2, 119.1, 124.0, 126.9, 127.0, 129.9, 131.7,
160.9 ppm. IR: ν
= 3061, 2922, 1725, 1615, 1565, 1310, 1180,
˜
max
941, 815, 774, 702 cm–1. HRMS (ES+): calcd. for C16H13O2 [M +
H]+ 237.0916; found 237.0916.
6-Methyl-4-(p-tolyl)-2H-chromen-2-one (16c): Colorless solid (98%,
184.0 mg); m.p. 74–76 °C. H NMR (400 MHz, CDC13): δ = 2.31
(s, 3 H, CH3), 2.44 (s, 3 H, CH3), 6.30 (s, 1 H, CHalkenyl), 7.27 (d,
J = 8.2 Hz, 2 H, CHar), 7.32 (s, 5 H, CHar) ppm. 13C NMR
(100 MHz, CDC13): δ = 20.9, 21.3, 114.8, 116.9, 118.7, 126.7,
1
154.2, 155.3, 159.5, 160.9 ppm. IR: ν
= 2959, 2872, 1725, 1606,
˜
max
1469, 1368, 1245, 1141, 1117, 867, 835, 752 cm–1. HRMS (ES+):
calcd. for C19H19O3 [M + H]+ 295.1334; found 295.1333.
128.3, 129.5, 132.4, 132.7, 139.7, 152.3, 155.6, 161.0 ppm. IR: ν
˜
max
4-(4-Isobutoxyphenyl)-2H-chromen-2-one (10c): Yellow oil (92%,
= 2921, 1726, 1615, 1566, 1419, 1362, 1255, 1181, 932, 818 cm–1.
1
203.1 mg). H NMR (400 MHz, CDC13): δ = 1.06 [d, J = 6.7 Hz, HRMS (ES+): calcd. for C17H15O2 [M + H]+ 251.1072; found
6 H, C(CH3)2], 2.11–2.17 (m, 1 H, CH), 3.80 (d, J = 6.5 Hz, 2 H,
OCH2), 6.35 (s, 1 H, CHalkenyl), 7.04 (d, J = 8.4 Hz, 2 H, CHar),
7.22–7.26 (m, 1 H, CHar), 7.40 (d, J = 8.4 Hz, 3 H, CHar), 7.53–
7.58 (m, 2 H, CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 19.2,
28.2, 74.5, 114.5, 114.8, 117.3, 119.1, 124.0, 127.0, 127.1, 129.8,
251.1073.
4-(4-Methoxyphenyl)-6-methyl-2H-chromen-2-one[5q] (17c): Color-
less solid (92%, 183.7 mg); m.p. 90–92 °C. 1H NMR (400 MHz,
CDC13): δ = 2.32 (s, 3 H, CH3), 3.87 (s, 3 H, OCH3), 6.29 (s, 1 H,
CHalkenyl), 7.03 (dd, J = 1.9, 6.7 Hz, 2 H, CHar), 7.24–7.33 (m, 3
H, CHar), 7.38 (dd, J = 1.9, 6.5 Hz, 2 H, CHar) ppm. 13C NMR
(100 MHz, CDC13): δ = 20.9, 55.3, 114.2, 114.5, 117.0, 118.8,
126.7, 127.5, 129.8, 132.7, 133.7, 152.3, 155.2, 160.7, 161.1 ppm.
131.7, 154.2, 155.4, 160.5, 160.9 ppm. IR: νmax = 2971, 2932, 1725,
˜
1605, 1507, 1368, 1245, 1180, 1117, 928, 837, 752 cm–1. HRMS
(ES+): calcd. for C19H19O3 [M + H]+ 295.1334; found 295.1334.
4-(4-Chlorophenyl)-2H-chromen-2-one[12a] (11c): Pale-yellow solid
IR: ν
= 2929, 2838, 1724, 1609, 1511, 1362, 1249, 1029, 933,
˜
max
1
(90%, 173.2 mg); m.p. 164–166 °C. H NMR (500 MHz, CDC13): 817 cm–1. HRMS (ES+): calcd. for C17H15O3 [M + H]+ 267.1021;
δ = 6.35 (s, 1 H, CHalkenyl), 7.21–7.25 (m, 1 H, CHar), 7.34–7.44 found 267.1021.
(m, 4 H, CHar), 7.49–7.51 (m, 2 H, CHar), 7.53–7.57 (m, 1 H,
4-(3-Methoxyphenyl)-6-methyl-2H-chromen-2-one (18c): Pale-yel-
CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 115.3, 117.4, 118.6,
low solid (94%, 187.7 mg); m.p. 97–99 °C. 1H NMR (400 MHz,
124.2, 126.6, 129.2, 129.7, 132.1, 133.5, 135.9, 154.1, 154.4,
CDC13): δ = 2.31 (s, 3 H, CH3), 3.84 (s, 3 H, OCH3), 6.32 (s, 1 H,
160.4 ppm. IR: ν
= 3070, 2922, 2853, 1720, 1604, 1363, 1181,
˜
max
CHalkenyl), 6.93–7.05 (m, 3 H, CHar), 7.24–7.34 (m, 3 H, CHar),
7.42 (t, J = 7.7 Hz, 1 H, CHar) ppm. 13C NMR (100 MHz, CDC13):
δ = 20.9, 55.4, 114.0, 114.9, 115.0, 116.9, 118.6, 120.7, 126.6, 129.9,
1104, 940, 836, 750 cm–1. HRMS (ES+): calcd. for C15H10ClO2 [M
+ H]+ 257.0369; found 257.0365.
4-(3-Chlorophenyl)-2H-chromen-2-one (12c): Pale-yellow solid
132.8, 133.8, 136.6, 152.2, 155.4, 159.7, 160.9 ppm. IR: ν
=
˜
max
(92%, 176.9 mg); m.p.122–124 °C. 1H NMR (400 MHz, CDC13): δ 2922, 1729, 1568, 1485, 1430, 1288, 1227, 1174, 1045, 937,
= 6.29 (s, 1 H, CHalkenyl), 7.16–7.20 (m, 1 H, CHar), 7.26 (d, J 819 cm–1. HRMS (ES+): calcd. for C17H15O3 [M + H]+ 267.1021;
= 7.0 Hz, 1 H, CHar), 7.33–7.53 (m, 6 H, CHar) ppm. 13C NMR found 267.1024.
(100 MHz, CDC13): δ = 115.5, 117.4, 118.5, 124.3, 126.5, 126.6,
4-(4-Isopropoxyphenyl)-6-methyl-2H-chromen-2-one (19c): Color-
128.4, 129.7, 130.2, 132.1, 134.9, 136.8, 154.0, 160.3 ppm. IR: ν
˜
max
less solid (90%, 198.7 mg); m.p. 85–87 °C. 1H NMR (400 MHz,
CDC13): δ = 1.38 [d, J = 5.8 Hz, 6 H, C(CH3)2], 2.32 (s, 3 H, CH3),
4.59–4.65 (m, 1 H, OCH), 6.29 (s, 1 H, CHalkenyl), 7.00 (d, J =
8.8 Hz, 2 H, CHar), 7.24–7.37 (m, 5 H, CHar) ppm. 13C NMR
= 2919, 1728, 1605, 1559, 1367, 1181, 936, 868, 751 cm–1. HRMS
(ES+): calcd. for C15H10ClO2 [M + H]+ 257.0369; found 257.0369.
4-(4-Fluorophenyl)-2H-chromen-2-one[5q] (13c): Pale-yellow solid
1
(93%, 167.6 mg); m.p. 140–142 °C. H NMR (500 MHz, CDC13): (100 MHz, CDC13): δ = 22.0, 70.0, 114.4, 115.7, 117.0, 118.8,
δ = 6.34 (s, 1 H, CHalkenyl), 7.19–7.25 (m, 3 H, CHar), 7.38–7.46 (m,
126.7, 129.9, 132.7, 133.6, 152.3, 155.3, 159.1 ppm. IR: ν
2978, 2921, 1727, 1614, 1568, 1506, 1245, 1174, 1114, 937,
=
˜
max
4 H, CHar), 7.53–7.56 (m, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 115.3, 116.0 (d, J = 21.4 Hz) 117.3, 118.8, 124.2, 818 cm–1. HRMS (ES+): calcd. for C19H19O3 [M + H]+ 295.1334;
126.7, 130.3 (d, J = 8.3 Hz), 131.1, 132.0, 154.1, 154.5, 160.5, 163.5 found 295.1333.
(d, J = 249.1 Hz) ppm. IR: ν
= 2919, 2850, 1741, 1606, 1018,
˜
max
4-(4-n-Butoxyphenyl)-6-methyl-2H-chromen-2-one (20c): Pale-yel-
low solid (92%, 212.8 mg); m.p. 62–64 °C. 1H NMR (400 MHz,
CDC13): δ = 0.98 (t, J = 7.3 Hz, 3 H, CH3), 1.48–1.54 (m, 2 H,
CH2), 1.76–1.82 (m, 2 H, CH2), 2.32 (s, 3 H, CH3), 4.02 (t, J =
943, 841, 752 cm–1. HRMS (ES+): calcd. for C15H10FO2 [M + H]+
241.0665; found 241.0688.
4-[3-(Trifluoromethyl)phenyl]-2H-chromen-2-one[12b] (14c): Pale-yel-
low solid (89%, 193.7 mg); m.p. 112–114 °C. H NMR (500 MHz, 6.6 Hz, 2 H, OCH2), 6.29 (s, 1 H, CHalkenyl), 7.01 (d, J = 8.5 Hz,
1
CDC13): δ = 6.33 (s, 1 H, CHalkenyl), 7.17–7.20 (m, 1 H, CHar),
7.30 (dd, J = 1.5, 8.0 Hz, 1 H, CHar), 7.36 (d, J = 8.4 Hz, 1 H,
2 H, CHar), 7.24–7.33 (m, 3 H, CHar), 7.36 (d, J = 8.5 Hz, 2 H,
CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 13.8, 19.2, 20.9,
CHar), 7.49–7.53 (m, 1 H, CHar), 7.57–7.65 (m, 3 H, CHar), 7.73 31.2, 67.8, 114.5, 114.7, 117.0, 118.8, 126.7, 127.3, 129.8, 132.7,
(d, J = 7.6 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ
= 116.0, 117.6, 118.6, 124.5, 125.3, 126.5, 129.6, 131.4, 131.7, 131.8,
133.6, 152.3, 155.3, 160.3, 161.1 ppm. IR: νmax = 2957, 2871, 1725,
˜
1608, 1510, 1248, 1179, 933, 819 cm–1. HRMS (ES+): calcd. for
C20H21O3 [M + H]+ 309.1491; found 309.1491.
132.4, 136.0, 154.1, 154.2, 160.3 ppm. IR: νmax = 3074, 1729, 1607,
˜
Eur. J. Org. Chem. 2010, 3945–3955
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3951

M. L. N. Rao, V. Venkatesh, D. N. Jadhav
FULL PAPER
4-(4-sec-Butoxyphenyl)-6-methyl-2H-chromen-2-one (21c): Yellow
oil (85%, 196.6 mg). H NMR (500 MHz, CDC13): δ = 0.99 (t, J
5,7-Dimethyl-4-phenyl-2H-chromen-2-one[6h] (27c): Yellow oil (88%,
165.2 mg). H NMR (400 MHz, CDC13): δ = 1.76 (s, 3 H, CH3),
1
1
= 7.4 Hz, 3 H, CH3), 1.32 (d, J = 6.1 Hz, 3 H, CH3), 1.61–1.80 (m, 2.36 (s, 3 H, CH3), 6.14 (s, 1 H, CHalkenyl), 6.80 (s, 1 H, CHar),
2 H, CH2), 2.31 (s, 3 H, CH3), 4.35–4.39 (m, 1 H, OCH), 6.28 (s, 7.05 (s, 1 H, CHar), 7.24–7.26 (m, 2 H, CHar), 7.41–7.42 (m, 3 H,
1 H, CHalkenyl), 6.97–7.00 (m, 2 H, CHar), 7.25 (s, 1 H, CHar), 7.29–
7.31 (m, 2 H, CHar), 7.33–7.36 (m, 2 H, CHar) ppm. 13C NMR 115.8, 116.1, 127.3, 128.5, 128.6, 129.4, 137.0, 139.6, 142.3, 155.2,
(125 MHz, CDC13): δ = 9.7, 19.1, 20.8, 29.0, 75.1, 114.3, 115.7, 156.7, 160.4 ppm. IR: ν = 2924, 1730, 1617, 1445, 1317, 1203,
116.9, 118.7, 126.7, 129.8, 132.6, 133.6, 152.2, 155.3, 159.4, 1159, 1069, 851, 775, 707 cm–1. HRMS (ES+): calcd. for C17H15O2
CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 21.2, 23.2, 115.5,
˜
max
161.1 ppm. IR: ν
= 2969, 2923, 1723, 1604, 1246, 1121, 1020, [M + H]+ 251.1072; found 251.1071.
˜
max
818 cm–1. HRMS (ES+): calcd. for C20H21O3 [M + H]+ 309.1491;
5,7-Dimethyl-4-(p-tolyl)-2H-chromen-2-one (28c): Colorless solid
found 309.1491.
1
(91%, 180.4 mg); m.p. 122–124 °C. H NMR (400 MHz, CDC13):
δ = 1.81 (s, 3 H, CH3), 2.38 (s, 3 H, CH3), 2.42 (s, 3 H, CH3), 6.15
(s, 1 H, CHalkenyl), 6.83 (s, 1 H, CHar), 7.07 (s, 1 H, CHar), 7.15 (d,
J = 7.9 Hz, 2 H, CHar), 7.24 (d, J = 7.8 Hz, 2 H, CHar) ppm. 13C
NMR (100 MHz, CDC13): δ = 21.2, 23.3, 115.7, 116.0, 127.2,
129.1, 129.3, 136.6, 137.0, 138.6, 142.1, 155.1, 156.9, 160.5 ppm.
4-(4-Isobutoxyphenyl)-6-methyl-2H-chromen-2-one (22c): Pale-yel-
low solid (82%, 189.6 mg); m.p. 88–90 °C. 1H NMR (500 MHz,
CDC13): δ = 1.03 [d, J = 6.9 Hz, 6 H, C(CH3)2], 2.07–2.15 (m, 1
H, CH), 2.31 (s, 3 H, CH3), 3.77 (d, J = 6.5 Hz, 2 H, OCH2), 6.29
(s, 1 H, CHalkenyl), 7.02 (dd, J = 1.9, 6.8 Hz, 2 H, CHar), 7.26 (d,
J = 8.0 Hz, 1 H, CHar), 7.30 (s, 1 H, CHar), 7.32 (s, 1 H, CHar),
7.36 (dd, J = 1.9, 6.5 Hz, 2 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 19.2, 20.9, 28.2, 74.5, 114.4, 114.7, 117.0, 118.8, 126.7,
IR: ν
= 2923, 1724, 1598, 1444, 1317, 1203, 1129, 1033, 937,
˜
max
849, 821 cm–1. HRMS (ES+): calcd. for C18H17O2 [M + H]+
265.1229; found 265.1229.
127.2, 129.8, 132.7, 133.6, 152.3, 155.3, 160.4, 161.1 ppm. IR: ν
˜
max
4-(4-Methoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (29c): Color-
less solid (86%, 180.8 mg); m.p. 126–128 °C. H NMR (400 MHz,
1
= 2959, 2924, 2871, 1724, 1608, 1569, 1510, 1363, 1247, 1177, 1028,
933, 819 cm–1. HRMS (ES+): calcd. for C20H21O3 [M + H]+
309.1491; found 309.1493.
CDC13): δ = 1.84 (s, 3 H, CH3), 2.38 (s, 3 H, CH3), 3.87 (s, 3 H,
OCH3), 6.16 (s, 1 H, CHalkenyl), 6.83 (s, 1 H, CHar), 6.95–6.97 (m,
2 H, CHar), 7.07 (s, 1 H, CHar), 7.18–7.26 (m, 2 H, CHar) ppm.
13C NMR (100 MHz, CDC13): δ = 21.2, 23.4, 55.3, 113.9, 115.7,
115.8, 116.1, 128.6, 129.4, 131.8, 137.0, 142.1, 155.2, 156.6, 160.0,
4-(4-Fluorophenyl)-6-methyl-2H-chromen-2-one[5q] (23c): Pale-yel-
1
low solid (95%, 181.2 mg); m.p. 158–160 °C. H NMR (500 MHz,
CDC13): δ = 2.27 (s, 3 H, CH3), 6.25 (s, 1 H, CHalkenyl), 7.12–7.18
(m, 3 H, CHar), 7.22 (d, J = 8.4 Hz, 1 H, CHar), 7.29 (dd, J =
1.9, 8.4 Hz, 1 H, CHar), 7.35–7.38 (m, 2 H, CHar) ppm. 13C NMR
(125 MHz, CDC13): δ = 20.9, 115.2, 115.3, 116.0 (d, J = 21.5 Hz),
117.1, 118.5, 126.4 (d, J = 4.7 Hz), 130.3 (d, J = 8.3 Hz), 131.2,
133.0, 133.9, 152.2, 154.5, 160.7, 163.4 (d, J = 249.1 Hz) ppm. IR:
160.6 ppm. IR: ν
= 2923, 1721, 1611, 1510, 1443, 1247, 1030,
˜
max
836 cm–1. HRMS (ES+): calcd. for C18H17O3 [M + H]+ 281.1178;
found 281.1177.
4-(3-Methoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (30c): Yellow
1
oil (89%, 187.1 mg). H NMR (400 MHz, CDC13): δ = 1.75 (s, 3
H, CH3), 2.29 (s, 3 H, CH3), 3.74 (s, 3 H, OCH3), 6.09 (s, 1 H,
CHalkenyl), 6.71–6.78 (m, 3 H, CHar), 6.87–6.90 (m, 1 H, CHar),
6.98 (s, 1 H, CHar), 7.24–7.27 (m, 1 H, CHar) ppm. 13C NMR
(100 MHz, CDC13): δ = 21.2, 22.9, 55.3, 113.1, 114.1, 115.4, 115.8,
115.9, 119.7, 129.4, 129.7, 137.0, 140.8, 142.2, 155.1, 156.4, 159.6,
ν
= 2922, 2852, 1721, 1603, 1507, 1316, 1225, 1183, 938,
˜
max
819 cm–1. HRMS (ES+): calcd. for C16H12FO2 [M + H]+ 255.0821;
found 255.0821.
7-Methyl-4-phenyl-2H-chromen-2-one[6h] (24c): Colorless solid
(86%, 152.3 mg); m.p. 59–61 °C. H NMR (500 MHz, CDC13): δ
1
160.4 ppm. IR: ν
= 2925, 1726, 1595, 1445, 1286, 1158, 1042,
˜
max
= 2.47 (s, 3 H, CH3), 6.29 (s, 1 H, CHalkenyl), 7.01 (d, J = 8.0 Hz,
1 H, CHar), 7.19 (s, 1 H, CHar), 7.34 (d, J = 8.0 Hz, 1 H, CHar),
851, 797, 721 cm–1. HRMS (ES+): calcd. for C18H17O3 [M + H]+
281.1178; found 281.1178.
7.41–7.43 (m, 2 H, CHar), 7.49 (t, J = 3.1 Hz, 3 H, CHar) ppm. 13
C
4-(4-Isopropoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (31c): Pale-
yellow solid (91%, 210.5 mg); m.p. 102–104 °C. 1H NMR
(500 MHz, CDC13): δ = 1.35 [d, J = 6.1 Hz, 6 H, C(CH3)2], 1.82
(s, 3 H, CH3), 2.36 (s, 3 H, CH3), 4.55–4.62 (m, 1 H, OCH), 6.14
(s, 1 H, CHalkenyl), 6.81 (s, 1 H, CHar), 6.90–6.93 (m, 2 H, CHar),
7.04 (s, 1 H, CHar), 7.13–7.16 (m, 2 H, CHar) ppm. 13C NMR
(125 MHz, CDC13): δ = 21.2, 21.9, 23.4, 70.03, 115.6, 115.8, 116.0,
128.6, 129.4, 131.5, 137.1, 142.1, 155.1, 156.7, 158.3, 160.7 ppm.
NMR (125 MHz, CDC13): δ = 21.5, 114.0, 116.5, 117.4, 125.3,
126.6, 128.4, 128.8, 129.5, 135.4, 143.1, 154.2, 155.6, 161.0 ppm.
IR: ν
= 2920, 1728, 1614, 1371, 860, 819, 707 cm–1. HRMS
˜
max
(ES+): calcd. for C16H13O2 [M + H]+ 237.0916; found 237.0918.
4-(4-Methoxyphenyl)-7-methyl-2H-chromen-2-one (25c): Colorless
solid (88%, 175.7 mg); m.p. 133–135 °C. 1H NMR (400 MHz,
CDC13): δ = 2.49 (s, 3 H, CH3), 3.92 (s, 3 H, OCH3), 6.31 (s, 1 H,
CHalkenyl), 7.07 (d, J = 8.7 Hz, 3 H, CHar), 7.24 (s, 1 H, CHar),
7.42–7.47 (m, 3 H, CHar) ppm. 13C NMR (100 MHz, CDC13): δ =
21.5, 55.3, 113.4, 114.2, 116.6, 117.4, 125.2, 126.6, 127.6, 129.8,
IR: ν
= 2975, 2925, 1724, 1611, 1507, 1444, 1355, 1244, 1119,
˜
max
951, 839 cm–1. HRMS (ES+): calcd. for C20H21O3 [M + H]+
309.1491; found 309.1491.
143.0, 150.7, 154.3, 155.3, 160.7, 161.1 ppm. IR: νmax = 2922, 2850,
˜
4-(4-Butoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (32c): Colorless
solid (88%, 212.7 mg); m.p. 86–88 °C. 1H NMR (500 MHz,
CDC13): δ = 0.97 (t, J = 7.2 Hz, 3 H, CH3), 1.48–1.52 (m, 2 H,
CH2), 1.76–1.81 (m, 2 H, CH2), 1.82 (s, 3 H, CH3), 2.36 (s, 3 H,
CH3), 3.99 (t, J = 6.5 Hz, 2 H, OCH2), 6.14 (s, 1 H, CHalkenyl),
6.81 (s, 1 H, CHar), 6.93 (dd, J = 2.3, 6.5 Hz, 2 H, CHar), 7.04 (s,
1729, 1608, 1512, 1373, 1255, 1026, 823 cm–1. HRMS (ES+): calcd.
for C17H15O3 [M + H]+ 267.1021; found 267.1021.
4-(3-Methoxyphenyl)-7-methyl-2H-chromen-2-one (26c): Pale-yel-
low solid (91%, 181.7 mg); m.p. 83–85 °C. 1H NMR (400 MHz,
CDC13): δ = 2.49 (s, 3 H, CH3), 3.89 (s, 3 H, OCH3), 6.34 (s, 1 H,
CHalkenyl), 6.99–7.08 (m, 4 H, CHar), 7.24 (s, 1 H, CHar), 7.42–7.47 1 H, CHar), 7.15 (dd, J = 2.3, 6.4 Hz, 2 H, CHar) ppm. 13C NMR
(m, 2 H, CHar) ppm. 13C NMR (100 MHz, CDC13): δ = 21.5, 55.3,
(125 MHz, CDC13): δ = 13.8, 19.2, 21.2, 23.4, 31.2, 67.8, 114.4,
113.9, 114.9, 116.4, 117.3, 120.6, 125.3, 126.6, 129.8, 136.6, 143.1,
115.7, 115.8, 116.0, 116.1, 128.6, 129.4, 131.6, 137.1, 142.1, 155.2,
154.2, 155.4, 159.7, 161.0 ppm. IR: ν
= 2922, 1729, 1592, 1372,
156.7, 159.6, 160.7 ppm. IR: ν
= 2957, 2929, 2870, 1723, 1611,
˜
˜
max
max
1221, 1039, 877, 812 cm–1. HRMS (ES+): calcd. for C17H15O3 [M
+ H]+ 267.1021; found 267.1021.
1509, 1444, 1245, 1028, 836 cm–1. HRMS (ES+): calcd. for
C21H23O3 [M + H]+ 323.1647; found 323.1646.
3952
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 3945–3955

Palladium-Catalyzed Synthesis of 4-Arylcoumarins
4-(4-sec-Butoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (33c): Pale- 113.2, 114.4, 116.5, 117.4, 125.3, 126.0, 126.5, 128.9, 129.4, 131.2,
yellow solid (82%, 198.3 mg); m.p. 62–64 °C. 1H NMR (500 MHz,
CDC13): δ = 0.99 (t, J = 7.4 Hz, 3 H, CH3), 1.31 (d, J = 6.1 Hz, 3
131.7, 133.8, 154.7, 156.2, 160.4, 160.5 ppm. IR: νmax = 2922, 2849,
˜
1727, 1605, 1511, 1248, 1179, 996, 819 cm–1. HRMS (ES+): calcd.
H, CH3), 1.60–1.80 (m, 2 H, CH2), 1.84 (s, 3 H, CH3), 2.36 (s, 3 for C20H15O3 [M + H]+ 303.1021; found 303.1022.
H, CH3), 4.33–4.36 (m, 1 H, OCH), 6.15 (s, 1 H, CHalkenyl), 6.82
1-(3-Methoxyphenyl)-3H-benzo[f]chromen-3-one (39c): Yellow oil
(79%, 179.1 mg). H NMR (500 MHz, CDC13): δ = 3.79 (s, 3 H,
OCH3), 6.36 (s, 1 H, CHalkenyl), 6.87–6.90 (m, 2 H, CHar), 7.03–
(s, 1 H, CHar), 6.93 (dd, J = 1.9, 6.5 Hz, 2 H, CHar), 7.05 (s, 1 H,
1
CHar), 7.15 (dd, J = 2.3, 6.6 Hz, 2 H, CHar) ppm. 13C NMR
(125 MHz, CDC13): δ = 9.7, 19.1, 21.2, 23.4, 29.0, 75.1, 115.6,
7.05 (m, 1 H, CHar), 7.14–7.18 (m, 1 H, CHar), 7.28 (d, J = 8.8 Hz,
115.8, 115.9, 128.6, 129.4, 131.4, 137.1, 142.1, 155.1, 156.7, 158.6,
1 H, CHar), 7.36–7.40 (m, 2 H, CHar), 7.49 (d, J = 8.8 Hz, 1 H,
160.7 ppm. IR: ν
= 2971, 2930, 1723, 1610, 1444, 1243,
˜
max
CHar), 7.81 (d, J = 8.0 Hz, 1 H, CHar), 7.97 (d, J = 9.1 Hz, 1 H,
CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 55.3, 112.8, 112.9,
114.8, 116.6, 117.3, 119.7, 125.3, 125.8, 126.7, 128.9, 129.2, 130.2,
844 cm–1. HRMS (ES+): calcd. for C21H23O3 [M + H]+ 323.1647;
found 323.1646.
4-(4-Isobutoxyphenyl)-5,7-dimethyl-2H-chromen-2-one (34c): Pale-
yellow solid (84%, 203.1 mg); m.p. 108–110 °C. 1H NMR
(500 MHz, CDC13): δ = 1.03 [d, J = 6.8 Hz, 6 H, C(CH3)2], 1.83
(s, 3 H, CH3), 2.06–2.14 (m, 1 H, CH), 2.36 (s, 3 H, CH3), 3.75 (d,
J = 6.3 Hz, 2 H, OCH2), 6.14 (s, 1 H, CHalkenyl), 6.82 (s, 1 H,
CHar), 6.94 (dd, J = 2.0, 6.8 Hz, 2 H, CHar), 7.05 (s, 1 H, CHar),
7.16 (dd, J = 2.2, 6.7 Hz, 2 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 19.3, 21.3, 23.5, 28.3, 74.6, 114.6, 115.8, 115.9, 116.1,
128.7, 129.5, 131.7, 137.2, 142.2, 155.3, 156.8, 159.8, 160.8 ppm.
131.2, 133.9, 140.7, 154.6, 156.2, 160.0, 160.3 ppm. IR: ν
=
˜
max
2923, 1729, 1589, 1546, 1430, 1213, 1042, 957, 819 cm–1. HRMS
(ES+): calcd. for C20H15O3 [M + H]+ 303.1021; found 303.1021.
1-(4-Isopropoxyphenyl)-3H-benzo[f]chromen-3-one (40c): Pale-yel-
low solid (80%, 198.2 mg); m.p. 72–74 °C. 1H NMR (500 MHz,
CDC13): δ = 1.40 [d, J = 6.1 Hz, 6 H, C(CH3)2], 4.62–4.67 (m, 1
H, OCH), 6.34 (s, 1 H, CHalkenyl), 6.96–6.98 (m, 2 H, CHar), 7.16–
7.25 (m, 3 H, CHar), 7.37–7.40 (m, 2 H, CHar), 7.48 (dd, J = 1.5,
8.9 Hz, 1 H, CHar), 7.81 (d, J = 8.4 Hz, 1 H, CHar), 7.96 (d, J =
9.1 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 21.9,
70.0, 113.1, 116.1, 116.3, 117.3, 125.2, 126.0, 126.4, 128.8, 128.8,
IR: ν
= 2959, 1722, 1610, 1508, 1244, 1028, 835 cm–1. HRMS
˜
max
(ES+): calcd. for C21H23O3 [M + H]+ 323.1647; found 323.1647.
4-(4-Fluorophenyl)-5,7-dimethyl-2H-chromen-2-one (35c): Pale-yel-
low solid (91%, 183.1 mg); m.p. 96–98 °C. 1H NMR (500 MHz,
129.3, 131.2, 131.3, 133.7, 154.6, 156.2, 158.7, 160.4 ppm. IR: ν
˜
max
= 2976, 2927, 1729, 1604, 1508, 1245, 1182, 1116, 819 cm–1. HRMS
CDC13): δ = 1.78 (s, 3 H, CH3), 2.37 (s, 3 H, CH3), 6.14 (s, 1 H, (ES+): calcd. for C22H19O3 [M + H]+ 331.1334; found 331.1333.
CHalkenyl), 6.82 (s, 1 H, CHar), 7.06 (s, 1 H, CHar), 7.13 (t, J =
1-(4-Butoxyphenyl)-3H-benzo[f]chromen-3-one (41c): Pale-brown
8.4 Hz, 2 H, CHar), 7.24–7.26 (m, 2 H, CHar) ppm. 13C NMR
solid (82%, 211.7 mg); m.p. 74–76 °C. 1H NMR (500 MHz,
(125 MHz, CDC13): δ = 21.3, 23.4, 115.4, 115.7 (d, J = 21.4 Hz),
CDC13): δ = 1.01 (t, J = 7.6 Hz, 3 H, CH3), 1.50–1.56 (m, 2 H,
115.8, 116.4, 116.4, 129.2 (d, J = 7.1 Hz), 129.5, 135.5, 136.7, 142.5,
CH2), 1.79–1.84 (m, 2 H, CH2), 4.05 (t, J = 6.1 Hz, 2 H, OCH2),
155.1, 155.6, 160.3, 162.9 (d, J = 246.8 Hz) ppm. IR: ν
= 2957,
˜
max
6.35 (s, 1 H, CHalkenyl), 6.97–7.00 (m, 2 H, CHar), 7.17–7.26 (m, 3
H, CHar), 7.37–7.51 (m, 3 H, CHar), 7.82 (t, J = 8.0 Hz, 1 H, CHar),
7.97 (t, J = 8.7 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13):
δ = 13.8, 19.2, 31.2, 67.8, 113.1, 114.9, 116.3, 116.3, 117.3, 125.2,
126.0, 126.5, 128.8, 129.3, 131.2, 131.4, 133.7, 154.6, 156.3, 159.9,
2928, 2868, 1723, 1612, 1508, 1407, 1355, 1242, 1159, 1068,
841 cm–1. HRMS (ES+): calcd. for C17H14FO2 [M + H]+ 269.0978;
found 269.0979.
1-Phenyl-3H-benzo[f]chromen-3-one[12d] (36c): Pale-yellow solid
1
(86%, 175.6 mg); m.p. 135–137 °C. H NMR (500 MHz, CDC13): 160.5 ppm. IR: ν
= 2957, 2870, 1728, 1605, 1511, 1246, 1178,
˜
max
δ = 6.38 (s, 1 H, CHalkenyl), 7.12–7.16 (m, 1 H, CHar), 7.23 (d, J =
819, 751 cm–1. HRMS (ES+): calcd. for C23H21O3 [M + H]+
6.9 Hz, 1 H, CHar), 7.35–7.41 (m, 3 H, CHar), 7.48–7.53 (m, 4 H, 345.1491; found 345.1491.
CHar), 7.83 (d, J = 8.0 Hz, 1 H, CHar), 7.99 (d, J = 8.7 Hz, 1 H,
1-(4-sec-Butoxyphenyl)-3H-benzo[f]chromen-3-one
(42c): Pale-
brown solid (82%, 211.8 mg); m.p. 87–89 °C. 1H NMR (500 MHz,
CDC13): δ = 1.01 (t, J = 7.4 Hz, 3 H, CH3), 1.36 (d, J = 6.0 Hz, 3
H, CH3), 1.64–1.84 (m, 2 H, CH2), 4.38–4.42 (m, 1 H, OCH), 6.36
(s, 1 H, CHalkenyl), 6.98 (dd, J = 2, 6.8 Hz, 2 H, CHar), 7.17–7.20
(m, 1 H, CHar), 7.24–7.27 (m, 2 H, CHar), 7.38–7.42 (m, 2 H,
CHar), 7.50 (d, J = 9.1 Hz, 1 H, CHar), 7.83 (d, J = 7.7 Hz, 1 H,
CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 112.9, 116.7, 116.7,
117.3, 125.3, 125.8, 126.6, 127.3, 128.9, 129.0, 129.1, 129.2, 131.2,
133.9, 139.4, 154.6, 156.4, 160.3 ppm. IR: νmax = 1730, 1546, 1513,
˜
996, 819, 700 cm–1. HRMS (ES+): calcd. for C19H13O2 [M + H]+
273.0916; found 273.0915.
1-(p-Tolyl)-3H-benzo[f]chromen-3-one (37c): Pale-yellow solid
(80%, 171.8 mg); m.p. 95–97 °C. H NMR (500 MHz, CDC13): δ CHar), 7.98 (d, J = 8.8 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz,
1
= 2.46 (s, 3 H, CH3), 6.35 (s, 1 H, CHalkenyl), 7.14–7.18 (m, 2 H,
CHar), 7.22–7.24 (m, 2 H, CHar), 7.28 (d, J = 8.0 Hz, 1 H, CHar),
CDC13): δ = 9.86, 19.2, 29.2, 75.4, 113.3, 116.3, 116.5, 117.5, 125.4,
126.2, 126.6, 129.0, 129.5, 131.4, 133.8, 154.8, 156.5, 159.2,
7.33 (d, J = 8.8 Hz, 1 H, CHar), 7.37–7.40 (m, 1 H, CHar), 7.50 (d, 160.7 ppm. IR: ν
= 2970, 1729, 1604, 1454, 1244, 1181, 995,
˜
max
J = 9.2 Hz, 1 H, CHar), 7.82 (d, J = 8.0 Hz, 1 H, CHar), 7.98 (d, J 819 cm–1. HRMS (ES+): calcd. for C23H21O3 [M + H]+ 345.1491;
= 9.1 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 21.4, found 345.1490.
113.1, 116.6, 117.4, 125.3, 125.9, 126.5, 127.3, 128.9, 129.4, 129.7,
1-(4-Isobutoxyphenyl)-3H-benzo[f]chromen-3-one (43c): Pale-brown
131.2, 133.8, 136.6, 139.2, 154.6, 156.6, 160.4 ppm. IR: ν
=
˜
solid (83%, 214.4 mg); m.p. 92–94 °C. 1H NMR (500 MHz,
CDC13): δ = 1.06 [d, J = 6.8 Hz, 6 H, C(CH3)2], 2.11–2.17 (m, 1
H, CH), 3.80 (d, J = 6.5 Hz, 2 H, OCH2), 6.34 (s, 1 H, CHalkenyl),
6.99 (d, J = 8.4 Hz, 2 H, CHar), 7.17–7.20 (m, 1 H, CHar), 7.25 (d,
J = 8.4 Hz, 2 H, CHar), 7.39 (t, J = 7.2 Hz, 2 H, CHar), 7.49 (d, J
max
2921, 1730, 1546, 1512, 1182, 996, 817 cm–1. HRMS (ES+): calcd.
for C20H15O2 [M + H]+ 287.1072; found 287.1075.
1-(4-Methoxyphenyl)-3H-benzo[f]chromen-3-one (38c): Pale-brown
solid (89%, 201.8 mg); m.p. 102–104 °C. 1H NMR (500 MHz,
CDC13): δ = 3.90 (s, 3 H, OCH3), 6.35 (s, 1 H, CHalkenyl), 7.01 (dd, = 9.2 Hz, 1 H, CHar), 7.82 (d, J = 7.6 Hz, 1 H, CHar), 7.97 (d, J
J = 1.9, 6.7 Hz, 2 H, CHar), 7.17–7.20 (m, 1 H, CHar), 7.28 (dd, J = 9.2 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 19.2,
= 1.9, 6.6 Hz, 2 H, CHar), 7.37–7.41 (m, 2 H, CHar), 7.50 (d, J =
8.8 Hz, 1 H, CHar), 7.83 (d, J = 8.0 Hz, 1 H, CHar), 7.98 (d, J = 128.8, 129.3, 131.2, 131.3, 133.7, 154.6, 156.3, 160.0, 160.5 ppm.
8.8 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ = 55.4, IR: νmax = 2959, 1729, 1605, 1510, 1245, 1176, 1027, 996, 818 cm–1.
28.2, 74.4, 113.1, 114.9, 116.3, 116.4, 117.3, 125.2, 126.0, 126.5,
˜
Eur. J. Org. Chem. 2010, 3945–3955
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3953

M. L. N. Rao, V. Venkatesh, D. N. Jadhav
FULL PAPER
HRMS (ES+): calcd. for C23H21O3 [M + H]+ 345.1491; found
345.1494.
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1-(3-Chlorophenyl)-3H-benzo[f]chromen-3-one (44c): Pale-yellow so-
lid (82%, 188.6 mg); m.p. 117–119 °C. 1H NMR (500 MHz,
CDC13): δ = 6.35 (s, 1 H, CHalkenyl), 7.18–7.25 (m, 3 H, CHar),
7.38–7.52 (m, 5 H, CHar), 7.85 (d, J = 8.0 Hz, 1 H, CHar), 8.01 (d,
J = 8.9 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ =
112.6, 117.1, 117.5, 125.6, 125.7, 125.8, 127.1, 129.1, 129.2, 129.5,
[2]
[3]
130.5, 131.4, 134.3, 135.3, 141.2, 154.8, 154.9, 160.1 ppm. IR: ν
˜
max
= 1730, 1514, 1454, 997, 948, 819 cm–1. HRMS (ES+): calcd. for
C19H12ClO2 [M + H]+ 307.0526; found 307.0523.
1-(4-Fluorophenyl)-3H-benzo[f]chromen-3-one (45c): Pale-yellow so-
lid (81%, 176.3 mg); m.p. 103–105 °C. 1H NMR (500 MHz,
CDC13): δ = 6.35 (s, 1 H, CHalkenyl), 7.17–7.25 (m, 4 H, CHar),
7.33–7.35 (m, 2 H, CHar), 7.41 (t, J = 7.7 Hz, 1 H, CHar), 7.51 (d,
J = 9.1 Hz, 1 H, CHar), 7.84 (d, J = 8.0 Hz, 1 H, CHar), 8.00 (d, J
= 9.1 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz, CDC13): δ =
112.9, 116.4 (d, J = 21.7 Hz), 117.0, 117.5, 125.5, 125.8, 126.9,
129.2, 129.3, 129.4, 129.5, 131.4, 134.2, 135.6, 154.9, 155.4, 160.2,
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163.4 (d, J = 249.1 Hz) ppm. IR: ν
= 1729, 1509, 1182, 997,
˜
max
819, 751 cm–1. HRMS (ES+): calcd. for C19H12FO2 [M + H]+
291.0821; found 291.0822.
1-[3-(Trifluoromethyl)phenyl]-3H-benzo[f]chromen-3-one (46c): Yel-
low oil (80%, 204.1 mg). 1H NMR (500 MHz, CDC13): δ = 6.37
(s, 1 H, CHalkenyl), 7.11 (d, J = 8.8 Hz, 1 H, CHar), 7.15–7.18 (m,
1 H, CHar), 7.40–7.45 (m, 2 H, CHar), 7.53 (d, J = 9.1 Hz, 1 H,
CHar), 7.56 (d, J = 7.3 Hz, 1 H, CHar), 7.65 (d, J = 6.9 Hz, 1 H,
CHar), 7.80 (d, J = 7.6 Hz, 1 H, CHar), 7.86 (d, J = 8.0 Hz, 1 H,
CHar), 8.02 (d, J = 8.8 Hz, 1 H, CHar) ppm. 13C NMR (125 MHz,
CDC13): δ = 112.3, 117.2, 117.4, 124.4, 125.3, 125.5, 126.0, 126.9,
128.8, 128.9, 129.2, 129.7, 130.9, 131.2, 134.3, 140.2, 154.6, 154.8,
159.8 ppm. IR: ν
= 2918, 1732, 1547, 1314, 1168, 1126, 1071,
˜
max
815 cm–1. HRMS (ES+): calcd. for C20H12F3O2 [M + H]+ 341.0789;
found 341.0788.
Supporting Information (see also the footnote on the first page of
this article): Spectroscopic data and HPLC traces of all the com-
pounds.
Acknowledgments
[6]
We thank the Department of Science and Technology (DST), New
Delhi for supporting this work under the green chemistry program
(SR/S5/GC-11/2008). V. V. and D. N. J. acknowledge the University
Grants Commission (UGC), New Delhi and Council of Scientific
and Industrial Research (CSIR), New Delhi, respectively, for re-
search fellowships.
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Published Online: May 27, 2010
Eur. J. Org. Chem. 2010, 3945–3955
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3955