A new palladium catalyzed protocol for atom-efficient cross-coupling reactions of?triarylbismuths with aryl halides and triflates

Article abstract of DOI:10.1016/j.tet.2008.04.011

A new palladium catalyzed protocol for an atom-efficient cross-coupling reaction of triarylbismuths with aryl halides and triflates has been described. The palladium catalytic system with Cs₂CO₃ base was found to be very efficient in DMA solvent to furnish excellent yields of cross-coupled functionalized biaryls in short reaction times.

Full text of DOI:10.1016/j.tet.2008.04.011

Tetrahedron 64 (2008) 5762–5772
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Tetrahedron
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A new palladium catalyzed protocol for atom-efficient cross-coupling reactions
of triarylbismuths with aryl halides and triflates
*
Maddali L.N. Rao , Deepak N. Jadhav, Debasis Banerjee
Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A new palladium catalyzed protocol for an atom-efficient cross-coupling reaction of triarylbismuths with
aryl halides and triflates has been described. The palladium catalytic system with Cs2CO3 base was found
to be very efficient in DMA solvent to furnish excellent yields of cross-coupled functionalized biaryls in
short reaction times.
Received 16 October 2007
Received in revised form 16 March 2008
Accepted 3 April 2008
Available online 8 April 2008
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Cross-coupling
Triarylbismuths
Palladium catalysis
Aryl bromides
Aryl iodides
Aryl triflates
1. Introduction
triarylbismuths toward cross-coupling was found to be a delicate
task and this could be one reason why triarylbismuths were
The role of organoboron, organotin, organosilicon, and other
organometallic reagents has been demonstrated to be vital to
obtain biaryls in organic synthesis.1–4 The importance of these
methods led to the development of numerous new catalytic pro-
tocols and new reagents.2,3 However, there is also a need for the
development of atom-efficient organometallic reagents, which can
react with more than 1 equiv of electrophilic coupling reagents5
in order to reduce the organometallic loadings for industrial scale
preparations.1f Triarylbismuth reagents with three aryl groups
on bismuth have attracted our attention as viable atom-efficient
organometallic coupling partners for C–C bond formations. Triar-
ylbismuths are non-toxic, stable to air, and can be readily prepared
by known procedures.6
Organobismuth compounds in general, are popular for N- and
O-arylation reactions under metal mediated or catalyzed condi-
tions.7 However, application of organobismuth compounds to C–C
bond formations are relatively scarce. The reactivity studies un-
dertaken with triarylbismuths for the conversion of Bi–C to C–C
under metal catalyzed cross-coupling conditions are very limited.8–
10 This is partly due to weak nature of the Bi–C bond and its facile
cleavage to give biaryls in the presence of metal catalyst even at
room temperature conditions.8a,9a In particular, promoting the
untapped as atom-efficient reagents for organic synthesis. Thus,
finding the right combination for general cross-coupling reactivity
often demands a systematic study. Our recent efforts in this di-
rection allowed us to realize the facile reactivity of triarylbismuth
for cross-coupling reaction with electrophilic coupling partners to
some extent.11 However, the metal catalyzed protocols available are
still limited toward the utilization of these reagents for C–C bond
formations in organic synthesis.
From our earlier studies of palladium catalyzed conditions, it
was also found that the role of catalyst precursor in combination
with base, solvent, and temperature bear tremendous effect on the
reactivity of triarylbismuths, hence play a decisive role for cross-
coupling reaction with electrophilic coupling partners.11 This was
also known with other cross-coupling reactions using organoboron
and other organometallic reagents.4 In continuation of our interest
in triarylbismuths for C–C bond formations, we now report a new
and novel palladium catalyzed protocol for atom-efficient cross-
coupling of triarylbismuths with aryl bromides, iodides, and
triflates.
2. Results and discussion
To develop a new palladium catalyzed protocol, our initial at-
tempts involved screening of palladium chloride as catalyst pre-
cursor in combination with triphenylphosphine (TPP) as a ligand. A
* Corresponding author. Tel./fax: þ91 512 259 7532.
E-mail address: maddali@iitk.ac.in (M.L.N. Rao).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.04.011

M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
5763
systematic study was carried out using a variety of bases and sol-
vents under different temperature conditions for the cross-cou-
pling reaction of 4-acetylphenyl bromide with triphenylbismuth,
and the results are given in Table 1.
4-acetyl as an electron-withdrawing substituent furnished good
yields of functionalized biphenyls (entries 1–3). The reactivity of o-,
m- and p-nitro substituted phenyl bromides was remarkable fur-
nishing corresponding biphenyls in good to excellent yields (entries
5–12). Notably, the poor cross-coupling reactivity reported with
2-nitrophenyl bromide due to sterics in the ortho position under
Suzuki coupling conditions12 was not operative in the present case,
thus giving moderate to good yields of products (entries 10–12).
The reaction of 4-cyano and 2-cyano substituted phenyl bromides
also produced 55–85% yields of the substituted biphenyls (entries
13–16). Similarly, the reactivity of para substituted phenyl bro-
mides containing trifluoromethyl, benzoyl, and carboethoxy groups
was found to be good to excellent (entries 17–23). Thus, aryl
bromides studied with electron-withdrawing groups showed good
to high cross-coupling reactivity with different triarylbismuths.
The cross-coupling reactions of electron-rich p-tolylbromide and
m-tolylbromide furnished moderate yields of cross-coupled bi-
phenyls (entries 24, 25). The reaction of o-tolylbromide produced
32% of the cross-coupled product with trianisylbismuth. Notably,
electron-rich substrates, which are otherwise known to show poor
reactivity in this type of reaction showed moderate reactivity with
triarylbismuths.
This investigation provided varied combinations of base and
solvent systems to obtain the desired cross-coupling in moderate
conversions. Thus, the reactions carried out with Cs2CO3 as base in
different solvents identified DMA (N,N-dimethylacetamide) fur-
nishing 79% conversion (entry 4) while, NMP and DMF led to 44%
and 71% conversions (entries 2 and 5). However, 1,4-dioxane and
THF solvent systems were found to be inefficient and did not pro-
vide respectable conversions (entries 1 and 3). Further examination
of DMA with different bases K3PO4, KOAc, and K2CO3 delivered
moderate cross-coupling conversion (entries 6–8). Next, lowering
the reaction temperature to 60 ꢀC had no positive effect, giving only
36% conversion with Cs2CO3 in DMA (entry 9). Strikingly, the cross-
coupling reaction carried out at 90 ꢀC improved the conversion to
89% in 2 h with 85% isolated product (entry 10). Further study with
varying Cs2CO3 base equivalents produced mixed conversions
(entry 11–13) revealing that 4 equiv of base is necessary to furnish
high cross-coupling conversion. A control reaction carried out
without base delivered only 16% cross-coupling conversion in-
dicating the role of base to activate triarylbismuth for cross-cou-
pling reaction (entry 14). From this study, it was clear that Cs2CO3
(4 equiv) in DMA with PdCl2 (0.09 equiv)/PPh3 (0.18 equiv) at 90 ꢀC
is an optimized condition for high cross-coupling conversion. At
this point, it is noteworthy to mention that the present protocol
is highly efficient as 3 equiv of aryl bromide reacted with 1 equiv
of triphenylbismuth cleanly to provide high yield of cross-coupling
product in short reaction time. Thus, the atom-efficiency of
triphenylbismuth where all the three phenyls were efficiently
coupled with 3 equiv of electrophilic coupling partner was thor-
oughly established. This is an important aspect to note with tri-
arylbismuths, which is not true with organoboron, organotin or
organosilicon reagents.
To further elaborate the general reactivity of the present
protocol with other electrophilic coupling reagents, we have un-
dertaken the cross-coupling study with functionalized aryl iodides
and the results are given in Table 3.
The reactivity of various substituted aryl iodides with different
triarylbismuths were found to be faster and efficient furnishing
good to high yields of the cross-coupled biphenyls in a short period
of 1 h. The cross-coupling reactivity with aryl iodides was found
to be efficient even with a lower palladium catalyst (0.06 equiv)
loading when compared to the corresponding reactivity with aryl
bromides. As shown in Table 3, the reactions of electron-deficient
aryl iodides afforded high yields of cross-coupling products with
various triarylbismuths. For example, aryl iodides substituted with
p-acetyl (entries 1–3), p-nitro (entries 4–6), p-cyano (entries 7–9),
p-chloro (entries 10–12), p-trifluoromethyl (entries 13–15), and
m-cyano (entry 16) produced high isolated yields of cross-coupled
products with different triarylbismuths. The reactions of electron-
rich p-methoxy and p-methyl substituted phenyl iodides furnished
moderate to good yields of the products (entries 17–19). This im-
proved reactivity of electron-rich aryl iodides is similar to that
observed with aryl bromides with different triarylbismuths.
Further, to broaden the scope, cross-coupling reactions of aryl
triflates with triphenylbismuth was studied. The cross-coupling
reaction of 4-acetylphenyl triflate as model substrate was studied
with triphenylbismuth in combination with various additives and
the results are given in Table 4.
The cross-coupling scope and generality of a variety of aryl
bromides with different triarylbismuths was investigated using
optimized conditions and the results are given in Table 2.
The reactions of electronically divergent phenyl bromides was
found to be high yielding furnishing a variety of functionalized
biphenyls with different triarylbismuths. Firstly, aryl bromides with
Table 1
Screening conditionsa,b
[Pd]
3
Ac
Br
+
BiPh3
T (ꢀC)
Ac
3
Entry
Base
Solvent
t (h)
Convf (%)
As shown, the initial cross-coupling reaction carried out at 90 ꢀC
for 3 h produced only 59% conversion of cross-coupled product
(entry 1). So, attempts were made to improve reactivity of aryl
triflates to obtain respectable cross-coupling conversion. Un-
fortunately, the reaction carried out lowering the temperature to
60 ꢀC did not improve the cross-coupling conversion (entry 2). The
observed lower reactivity with aryl triflate could be attributed to the
unstable nature of the intermediate Pd(II) complex that is expected
to form during initial oxidative addition of aryl triflate to Pd(0). The
replacement of triflate ion with halides by salt additives was dem-
onstrated in the literature to improve the stability and reactivity
of Pd(II) intermediate.13 Hence, we screened the reaction in the
presence of various additives to check their effect for improving the
cross-coupling conversion. As shown in Table 4, the presence of
various additives showed a positive effect on the cross-coupling
conversion. For example, the reactions carried out with the addi-
tives such as LiCl (entry 3), KCl (entry 4), KBr (entry 5), LiBr (entry 6),
tetrabutylammonium iodide (TBAI) (entry 8), tetrabutylammonium
1
2
3
4
5
6
7
8
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
K3PO4
KOAc
K2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
None
80
80
80
80
80
80
80
80
60
90
90
90
90
90
1,4-Dioxane
NMP
THF
DMA
DMF
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
2
2
2
3
3
3
3
3
3
2
2
2
2
2
14
44
02
79
71
56
56
53
36
89b
54c
65d
76e
16
9
10
11
12
13
14
a
Conditions: BiPh3 (1 equiv), 4-acetylphenyl bromide (3.6 equiv), PdCl2
(0.09 equiv), PPh3 (0.18 equiv), base (4 equiv), and solvent (3 mL).
b
4-Acetylphenyl bromide (3.3 equiv) for entries 10–14.
With base (1 equiv).
With base (2 equiv).
With base (3 equiv).
c
d
e
f
Measured by GC analysis.

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M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
Table 2
Cross-coupling of aryl bromides with triarylbismuthsa,b
PdCl2 (0.09 equiv)
PPh3 (0.18 equiv)
3
Br
+
Bi
3
Cs2CO3 (4 equiv)
90 °C, 2 h, DMA
R1
3
R2
R2
Product
R1
Entry
1
R1–X
BiAr3
BiPh3
Yieldc (%)
85
1a
1b
1c
Ac
Ac
2
3
Bi(p-anisyl)3
Bi(p-tolyl)3
76
88
Ac
Br
OMe
Me
Ac
4
5
6
BiPh3
2a
2b
2c
85
75
83
O2N
O2N
Bi(p-anisyl)3
Bi(p-tolyl)3
O2N
Br
OMe
Me
O2N
7
8
9
BiPh3
3a
3b
3c
80
67
81
O2N
Br
OMe
Me
Bi(p-anisyl)3
Bi(p-tolyl)3
O2N
O2N
O2N
10
11
12
BiPh3
4a
4b
4c
72
63
70
NO2
Br
NO2
OMe
Bi(p-anisyl)3
Bi(p-tolyl)3
NO2
Me
NO2
13
14
15
BiPh3
5a
5b
5c
69
79
85
NC
Bi(p-anisyl)3
Bi(p-tolyl)3
NC
Br
NC
NC
OMe
Me
Br
CN
16
BiPh3
6a
55
CN
17
18
BiPh3
7a
7b
84
72
F3C
Bi(p-anisyl)3
F3C
Br
F3C
F3C
OMe
Me
19
20
Bi(p-tolyl)3
7c
8a
62
69
BiPh3
PhOC
PhOC
EtOOC
PhOC
Br
21
22
Bi(p-tolyl)3
8b
9a
72
70
Me
Me
BiPh3
EtOOC
Br
23
Bi(p-tolyl)3
9b
90
EtOOC

M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
5765
Table 2 (continued )
Entry
R1–X
BiAr3
Product
OMe
Yieldc (%)
52
24
25
Bi(p-anisyl)3
10a
11a
Me
Br
Br
Me
OMe
Bi(p-anisyl)3
58
32
Me
Me
Br
OMe
26
Bi(p-anisyl)3
12a
Me
Me
a
Reaction conditions: BiAr3 (1 equiv), aryl bromide (3.3 equiv), PdCl2 (0.09 equiv), PPh3 (0.18 equiv), Cs2CO3 (4 equiv), DMA (3 mL), 90 ꢀC, and 2 h.
Homo-coupling biaryls from triarylbismuths formed as minor side products.
Isolated yields obtained after column chromatography. Yields are calculated based on the amount of triarylbismuth used.
b
c
Table 3
Cross-coupling of aryl iodides with triarylbismuthsa,b
PdCl2 (0.06 equiv)
PPh3 (0.12 equiv)
3
I
Bi
+
3
Cs2CO3 (4 equiv)
90 °C, 1 h, DMA
R1
3
R2
R2
R1
Product
Entry
1
R1–X
BiAr3
BiPh3
Yieldc (%)
85
1a
1b
Ac
2
Bi(p-anisyl)3
76
Ac
I
Ac
OMe
Me
3
4
Bi(p-tolyl)3
1c
2a
81
96
Ac
BiPh3
O2N
5
6
Bi(p-anisyl)3
Bi(p-tolyl)3
2b
2c
74
94
O2N
I
O2N
O2N
OMe
Me
7
BiPh3
5a
93
72
92
70
74
80
NC
NC
NC
Cl
8
Bi(p-anisyl)3
Bi(p-tolyl)3
BiPh3
5b
NC
Cl
I
OMe
Me
9
5c
10
11
12
13a
13b
13c
Bi(p-anisyl)3
Bi(p-tolyl)3
I
Cl
OMe
Me
Cl
13
14
15
BiPh3
7a
7b
7c
87
85
92
F3C
F3C
Bi(p-anisyl)3
Bi(p-tolyl)3
F3C
I
OMe
Me
F3C
I
16
BiPh3
14a
87
NC
NC
17
18
BiPh3
15a
10a
10a
52
79
71
MeO
MeO
Br
I
Bi(p-tolyl)3
Bi(p-anisyl)3
MeO
H3C
Me
19
H3C
OMe
a
Reaction conditions: BiAr3 (1 equiv), aryl iodide (3.3 equiv), PdCl2 (0.06 equiv), PPh3 (0.12 equiv), Cs2CO3 (4 equiv), DMA (3 mL), 90 ꢀC, and 1 h.
Homo-coupling biaryls from triarylbismuths formed as minor side products.
Isolated yields obtained after column chromatography. Yields are calculated based on the amount of triarylbismuth used.
b
c

5766
M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
Table 4
bromide (TBAB) (entry 9), NaBr (entry 10), and KI (entry 11)
Screening with different additivesa,b
produced improved conversion in the range of 62–80% with the
exception of silver iodide (entry 7). This also revealed that TBAB and
TBAI were equally effective at producing good conversion (entries
12–15). Further, a cross-coupling reaction carried out with catalyst
loading of PdCl2 (0.06 equiv)/PPh3 (0.12 equiv) and with TBAB
(1.1 equiv) also produced excellent conversion (entry 15) and,
hence, we decided to further investigate this reactivity with other
triflates using these conditions. The reactivity of various function-
alized aryl triflates with different triarylbismuths under optimized
palladium protocol condition is shown in Table 5.
Thus, the reactions carried out using electronically divergent
aryl triflates produced excellent cross-coupling yields with differ-
ent triarylbismuths. For example, the reactions of variety of elec-
tron-deficient phenyl triflates substituted with p- and m-acetyl
groups (entries 1–3 and 7–9), p-nitro (entries 4–6), p-cyano (entries
10–12), m-cyano (entries 13–15), p-chloro (entries 16–18), and
p-fluoro (entry 19) produced good to high isolated yields of
the functionalized biaryls with different triarylbismuths. The
cross-coupling reaction of 2-naphthyl triflate with different triar-
ylbismuths furnished good yields of the corresponding cross-cou-
pling products (entries 20–22). Strikingly, the reactivity of various
triarylbismuths was unaffected by the change in electronics of the
aryl rings in triarylbismuths, thus furnishing consistently good to
[Pd]
3
Ac
OTf
+ BiPh3
Ac
3
Entry
Additive (equiv)
T (ꢀC)
t (h)
Convc (%)
1
2
3
4
5
6
7
8
None
None
90
60
90
90
90
90
90
90
90
90
90
90
80
80
90
3
3
3
3
3
3
3
3
3
3
3
3
5
5
1
59
47
78
70
77
68
03
80
72
62
74
83
85
83
79d
LiCl (9.9)
KCl (9.9)
KBr (9.9)
LiBr(9.9)
AgI (9.9)
TBAI (9.9)
TBAB (9.9)
NaBr (6.6)
KI (6.6)
TBAI (3.3)
TBAB (3.3)
TBAI (3.3)
TBAB (1.1)
9
10
11
12
13
14
15
a
Conditions: BiPh3 (1 equiv), aryl triflate (3.3 equiv), PdCl2 (0.09 equiv), PPh3
(0.18 equiv), Cs2CO3 (4 equiv), additive, and DMA (3 mL).
b
Homo-coupling product biphenyl from triphenylbismuth formed as minor side
product.
c
Measured by GC analysis.
d
With catalyst loading of PdCl2 (0.06 equiv)/PPh3 (0.12 equiv).
Table 5
Cross-coupling of aryl triflates with triarylbismuthsa,b
PdCl2 (0.06 equiv)
PPh3 (0.12 equiv)
Bi
3
OTf
+
3
Cs2CO3 (4 equiv)
TBAB (1.1 equiv)
90 °C, 1 h, DMA
R1
R2
R2
3
R1
Entry
1
R1–X
BiAr3
BiPh3
Product
Yieldc (%)
74
1a
1b
1c
2a
2b
2c
Ac
Ac
2
3
4
5
6
Bi(p-anisyl)3
Bi(p-tolyl)3
BiPh3
75
82
74
77
84
Ac
OTf
OTf
OMe
Me
Ac
O2N
O2N
O2N
Bi(p-anisyl)3
Bi(p-tolyl)3
O2N
OMe
Me
7
8
9
BiPh3
16a
16b
16c
75
82
87
Ac
OTf
OMe
Bi(p-anisyl)3
Bi(p-tolyl)3
Ac
Ac
Me
Ac
10
11
BiPh3
5a
5b
78
73
NC
Bi(p-anisyl)3
NC
NC
OMe
NC
OTf
12
Bi(p-tolyl)3
5c
80
Me

M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
5767
Table 5 (continued )
Entry
R1–X
BiAr3
Product
Yieldc (%)
65
13
14
15
BiPh3
14a
14b
14c
NC
OTf
OMe
Me
Bi(p-anisyl)3
84
74
NC
NC
Bi(p-tolyl)3
NC
16
17
BiPh3
13a
13b
60
63
Cl
Bi(p-anisyl)3
Cl
OTf
Cl
OMe
Me
18
19
Bi(p-tolyl)3
13c
17a
71
51
Cl
Bi(p-anisyl)3
F
OTf
F
OMe
20
21
BiPh3
18a
18b
74
79
OMe
Me
Bi(p-anisyl)3
OTf
22
Bi(p-tolyl)3
18c
76
a
Reaction conditions: BiAr3 (1 equiv), aryl triflate (3.3 equiv), PdCl2 (0.06 equiv), PPh3 (0.12 equiv), Cs2CO3 (4 equiv), TBAB (1.1 equiv), DMA (3 mL), 90 ꢀC, and 1 h.
Homo-coupling biaryls from triarylbismuths formed as a minor side products.
Isolated yields obtained after column chromatography. Yields are calculated based on the amount of triarylbismuth used.
b
c
high yields of the cross-coupled products with different electro-
philic coupling partners such as aryl bromides, iodides, and
triflates.
were purified by standard purification procedures. Analytical thin
layer chromatography (TLC) was performed using silica gel GF254
(Spectrochem) coated glass plates or using aluminum sheets pre-
coated with silica gel 60 F254 (Merck). Visualization of TLC plate was
accomplished with UV lamp or in iodine chamber. The column
chromatography was performed using silica gel 100–200 mesh size
(SD Fine-Chem Limited) with ethyl acetate/petroleum ether as
an eluent system. Melting points were uncorrected and measured
using JSGW melting point apparatus (Jain Scientific Glass Works,
Ambala cantt, India). IR spectra were recorded on a Bruker vector
22 FT-IR spectrophotometer. 1H and 13C NMR spectra were recorded
on a JEOL-Lambda (400 MHz) spectrometer using CDCl3 as a solvent
and chemical shift values are expressed in parts per million (ppm)
from tetramethylsilane (TMS) as an internal standard. Triaryl-
bismuths were prepared by standard protocols.6,8a,b GC analysis of
the crude reaction mixtures and also of the pure isolated products
was performed using Perkin Elmer (Clarus 500 Gas Chromato-
graph) system. ESI-MS spectra were measured on Waters HAB213
Q-Tof Premier Micro mass spectrometer. All aryl halides were
purchased from Acros Organics and triflates were prepared
according to the reported procedure.14
3. Conclusion
We have disclosed an improved cross-coupling reactivity of
triarylbismuths toward aryl bromides, iodides, and triflates under
the present palladium catalyzed protocol. The simplicity associated
with the present palladium catalyzed protocol comprises the uti-
lization of routinely used palladium catalyst precursor and triphe-
nylphosphine ligand. The efficient reactivity of the present catalytic
protocol is evident from high yields obtained in short reaction
times using different electrophilic coupling partners such as aryl
bromides, iodides, and triflates with different triarylbismuths. The
high atom-efficiency of triarylbismuths demonstrated by reacting
with 3 equiv of electrophilic coupling partners further defines its
breadth and versatility, which is not known with organoboron,
organosilicon, organotin, and similar reagents. Thus, the present
study and established new palladium protocol is expected to
provide additional opportunity to exploit the inherent advantage
associated with triarylbismuths as atom-efficient reagents for ap-
plications in organic synthesis.
4.1.1. Representative procedure for cross-coupling reaction of aryl
bromides with triarylbismuths
4. Experimental section
4.1. General
A hot-oven-dried Schlenk tube was charged with 4-bromoace-
tophenone (0.825 mmol, 0.164 g) followed by triphenylbismuth
(0.25 mmol, 0.11 g), Cs2CO3 (1 mmol, 0.326 g), triphenylphosphine
(0.045 mmol, 0.012 g), PdCl2 (0.0225 mmol, 0.004 g), and DMA
(3 mL) solvent under nitrogen atmosphere. The reaction mixture
was stirred at 90 ꢀC for 2 h. The contents of the mixture were cooled
All reactions were carried out in hot-oven-dried Schlenk tubes
under nitrogen atmosphere using anhydrous solvents. All solvents

5768
M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
to room temperature and quenched with dil. HCl (10 mL), extracted
with ethyl acetate (3ꢁ10 mL). The combined organic extract was
washed with water (2ꢁ10 mL) and brine (10 mL), dried over an-
hydrous MgSO4 and was concentrated under vacuo to afford the
crude product. The crude product was further purified on silica gel
by column chromatography using 2% ethyl acetate in petroleum
ether to afford 4-acetylbiphenyl, 1a (0.125 g) in 85% yield based on
the amount of triphenylbismuth used.
1494, 1461, 1442, 1398, 1360, 1291, 1265, 1199, 1134, 1031, 1012, 958,
817, 710, 641, 590 cmꢂ1
.
4.2.3. 4-Acetyl-40-methylbiphenyl15b (1c)
The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 1c as a white
solid; Mp 117–118 ꢀC (lit. 119–120 ꢀC); Rf (10% ethyl acetate in pe-
troleum ether) 0.25; dH (400 MHz, CDCl3): 8.00 (d, 2H, J¼8.3 Hz,
CHar), 7.65 (d, 2H, J¼8.3 Hz, CHar), 7.51 (d, 2H, J¼8.0 Hz, CHar), 7.26
(d, 2H, J¼8.6 Hz, CHar), 2.61 (s, 3H, COCH3), 2.39 (s, 3H, CH3); dC
(100 MHz, CDCl3): 197.7, 145.7, 138.2, 136.9, 135.5, 129.6, 128.9,
127.0, 126.9, 26.6, 21.1; nmax (KBr): 2921, 1679, 1599, 1527, 1493,
1422, 1397, 1360, 1325, 1264, 1199, 1134, 1003, 960, 849, 807, 751,
4.1.2. Representative procedure for cross-coupling reaction of aryl
iodides with triarylbismuths
A hot-oven-dried Schlenk tube was charged with 4-iodoaceto-
phenone (0.825 mmol, 0.203 g) followed by triphenylbismuth
(0.25 mmol, 0.11 g), Cs2CO3 (1 mmol, 0.326 g), triphenylphosphine
(0.03 mmol, 0.0078 g), PdCl2 (0.015 mmol, 0.0027 g), and DMA
(3 mL) solvent under nitrogen atmosphere. The reaction mixture
was stirred at 90 ꢀC for 1 h. The contents of the mixture were cooled
to room temperature and quenched with dil HCl (10 mL), extracted
with ethyl acetate (3ꢁ10 mL). The combined organic extract was
washed with water (2ꢁ10 mL) and brine (10 mL), dried over
anhydrous MgSO4 and was concentrated under vacuo to afford the
crude product. The crude product was further purified on silica gel
by column chromatography (2% ethyl acetate in petroleum ether) to
afford 4-acetylbiphenyl, 1a (0.125 g) in 85% yield based on the
amount of triphenylbismuth used.
636 cmꢂ1
.
4.2.4. 4-Nitrobiphenyl15b (2a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 2a as a pale
yellow solid; Mp 107–108 ꢀC(lit. 108 ꢀC); Rf (10% ethyl acetate in
petroleum ether) 0.43; dH (400 MHz, CDCl3): 8.28 (d, 2H, J¼8.8 Hz,
CHar), 7.72 (d, 2H, J¼8.8 Hz, CHar), 7.61 (d, 2H, J¼7.1 Hz, CHar), 7.41–
7.50 (m, 3H, CHar); dC (100 MHz, CDCl3): 147.6, 147.0, 138.7, 129.1,
128.8, 127.7, 127.3, 124.1; nmax (KBr): 3074, 2925, 2835, 1685, 1592,
1512, 1344, 1104, 851, 738, 693, 468 cmꢂ1
.
4.2.5. 4-Methoxy-40-nitrobiphenyl15c (2b)
4.1.3. Representative procedure for cross-coupling reaction of aryl
triflates with triarylbismuths
A hot-oven-dried Schlenk tube was charged with 4-acetyl-
phenyl triflate (0.825 mmol, 0.221 g) followed by triphenylbismuth
(0.25 mmol, 0.11 g), Cs2CO3 (1 mmol, 0.326 g), tetrabutylammo-
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 2b as
a yellow solid; Mp 104–105 ꢀC (lit. 107–108 ꢀC); Rf (10% ethyl ace-
tate in petroleum ether) 0.50; dH (400 MHz, CDCl3): 8.24 (d, 2H,
J¼8.5 Hz, CHar), 7.66 (d, 2H, J¼8.5 Hz, CHar), 7.55 (d, 2H, J¼8.5 Hz,
CHar), 7.00 (d, 2H, J¼8.8 Hz, CHar), 3.85 (s, 3H, OCH3); dC (100 MHz,
CDCl3): 160.4, 147.2, 146.5, 131.0, 128.5, 127.0, 124.1, 114.5, 55.4; nmax
(KBr): 3058, 2921, 2839, 1598, 1511, 1341, 1246, 1180, 1106, 1023,
niumbromide
(0.275 mmol,
0.088 g),
triphenylphosphine
(0.03 mmol, 0.0078 g), PdCl2 (0.015 mmol, 0.0027 g), and DMA
(3 mL) solvent under nitrogen atmosphere. The reaction mixture
was stirred at 90 ꢀC for 1 h. The contents of the mixture were cooled
to room temperature and quenched with dil HCl (10 mL), extracted
with ethyl acetate (3ꢁ10 mL). The combined organic extract was
washed with water (2ꢁ10 mL) and brine (10 mL), dried over an-
hydrous MgSO4, and was concentrated under vacuo to get crude
product. The crude product was further purified on silica gel by
column chromatography (2% ethyl acetate in petroleum ether) to
afford 4-acetylbiphenyl, 1a (0.109 g) in 74% yield based on the
amount of triphenylbismuth used.
836, 755, 719, 694 cmꢂ1
.
4.2.6. 4-Methyl-40-nitrobiphenyl15d (2c)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 2c as a pale
yellow solid; Mp 134–135 ꢀC (lit. 140–141 ꢀC);15e Rf (10% ethyl ac-
etate in petroleum ether) 0.55; dH (400 MHz, CDCl3): 8.25 (d, 2H,
J¼8.8 Hz, CHar), 7.69 (d, 2H, J¼8.8 Hz, CHar), 7.51 (d, 2H, J¼8.0 Hz,
CHar), 7.28 (d, 2H, J¼8.0 Hz, CHar), 2.41 (s, 3H, CH3); dC (100 MHz,
CDCl3): 147.5, 146.8, 139.0, 135.8, 129.8, 127.4, 127.2, 124.0, 21.2; nmax
(KBr): 3078, 2924, 2852, 1595, 1513,1483, 1397, 1338, 1294, 1189,
4.2. Spectral data
1107, 1004, 853, 824, 753, 720, 696 cmꢂ1
.
4.2.1. 4-Acetylbiphenyl15a (1a)
The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 1a as a white
solid; Mp 117–118 ꢀC (lit. 115–118 ꢀC); Rf (10% ethyl acetate in pe-
troleum ether) 0.25; dH (400 MHz, CDCl3): 8.02 (d, 2H, J¼8.3 Hz,
CHar), 7.67 (d, 2H, J¼8.1 Hz, CHar), 7.61 (d, 2H, J¼7.3 Hz, CHar), 7.46
(t, 2H, J¼7.6 Hz, CHar), 7.39 (t, 1H, J¼7.3 Hz, CHar), 2.62 (s, 3H,
COCH3); dC (100 MHz, CDCl3): 197.7, 145.7, 139.8, 135.8, 128.9, 128.9,
128.2, 127.2, 127.1, 26.6; nmax (KBr): 3075, 2996, 2919, 1678, 1598,
4.2.7. 3-Nitrobiphenyl16a (3a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 3a as a pale
yellow solid; Mp 54–56 ꢀC (lit. 58.5–59.5 ꢀC);16b Rf (10% ethyl ace-
tate in petroleum ether) 0.43; dH (400 MHz, CDCl3): 8.43 (s, 1H,
CHar), 8.18 (d, 1H, J¼7.8 Hz, CHar), 7.91 (d, 1H, J¼7.6 Hz, CHar), 7.57–
7.62 (m, 3H, CHar), 7.40–7.50 (m, 3H, CHar); dC (100 MHz, CDCl3):
148.7, 142.8, 138.6, 133.0, 129.6, 129.1, 128.5, 127.1, 122.0; nmax (KBr):
3081, 2922, 2851, 1577, 1528, 1499, 1472, 1349, 1291, 1043, 993, 897,
1400, 1360, 1262, 1005, 837, 764, 686, 593 cmꢂ1
.
873, 812, 767, 731, 695, 675 cmꢂ1
.
4.2.2. 4-Acetyl-40-methoxybiphenyl15b (1b)
The crude product was purified on SiO2 by column chroma-
tography (10% ethyl acetate in petroleum ether) to give 1b as a pale
yellow solid; Mp 145–146 ꢀC (lit. 154–155 ꢀC); Rf (10% ethyl acetate
in petroleum ether) 0.15; dH (400 MHz, CDCl3): 7.98 (d, 2H, J¼7.8 Hz,
CHar), 7.62 (d, 2H, J¼8.0 Hz, CHar), 7.56 (d, 2H, J¼8.1 Hz, CHar), 6.98
(d, 2H, J¼8.3 Hz, CHar), 3.84 (s, 3H, OCH3), 2.60 (s, 3H, COCH3); dC
(100 MHz, CDCl3): 197.7, 159.9, 145.3, 135.2, 132.2, 128.9, 128.3,
126.6, 114.4, 55.3, 26.6; nmax (KBr): 2924, 2851, 1675, 1599, 1527,
4.2.8. 4-Methoxy-30-nitrobiphenyl16a (3b)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 3b as a pale
yellow solid; Mp 76–77 ꢀC (lit.79–81 ꢀC); Rf (10% ethyl acetate in
petroleum ether) 0.35; dH (400 MHz, CDCl3): 8.37–8.38 (m, 1H,
CHar), 8.11 (d, 1H, J¼8.3 Hz, CHar), 7.84 (d, 1H, J¼7.8 Hz, CHar), 7.52–
7.56 (m, 3H, CHar), 6.97–7.01 (m, 2H, CHar), 3.85 (s, 3H, OCH3); dC
(100 MHz, CDCl3): 160.0, 148.7, 142.4, 132.4, 131.0, 129.6, 128.2,

M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
5769
121.3, 114.5, 55.4; nmax (KBr): 3082, 3017, 2961, 2929, 2837, 1607,
OCH3); dC (100 MHz, CDCl3): 160.2, 145.2, 132.5, 131.4, 128.3, 127.1,
119.1, 114.5, 110.0, 55.4; nmax (KBr): 3039, 2962, 2840, 2219, 1602,
1517, 1490, 1396, 1292, 1239, 1173, 1109, 1035, 855, 824, 737,
1511, 1348, 1299, 1246, 1177, 1111, 1021, 876, 831, 804, 740, 719,
679 cmꢂ1
.
629 cmꢂ1
.
4.2.9. 4-Methyl-30-nitrobiphenyl16c,d (3c)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 3c as a pale
yellow solid; Mp 75–76 ꢀC (lit. 76–77 ꢀC); Rf (10% ethyl acetate in
petroleum ether) 0.55; dH (400 MHz, CDCl3): 8.41 (s, 1H, CHar), 8.15
(d, 1H, J¼8.1 Hz, CHar), 7.88 (d, 1H, J¼7.8 Hz, CHar), 7.57 (t, 1H,
J¼7.8 Hz, CHar), 7.50 (d, 2H, J¼8.1 Hz, CHar), 7.28 (d, 2H, J¼8.1 Hz,
CHar), 2.40 (s, 3H, CH3); dC (100 MHz, CDCl3): 148.7, 142.8, 138.5,
135.8, 132.8, 129.8, 129.6, 126.9, 121.7. 21.1; nmax (KBr): 3087, 3025,
2922, 2854, 1582, 1529, 1380, 1346, 1293, 1260, 1186, 1084, 1037,
4.2.15. 4-Cyano-40-methylbiphenyl16f (5c)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 5c as a white
solid; Mp 104–105 ꢀC (lit. 104–106 ꢀC); Rf (10% ethyl acetate in
petroleum ether) 0.40; dH (400 MHz, CDCl3): 7.63–7.70 (m, 4H,
CHar), 7.47 (d, 2H, J¼8.3 Hz, CHar), 7.27 (d, 2H, J¼7.8 Hz, CHar), 2.40
(s, 3H, CH3); dC (100 MHz, CDCl3): 145.5, 138.7, 136.2, 132.5, 129.8,
127.4, 127.0, 119.0, 110.5, 21.1; nmax (KBr): 3033, 2955, 2919, 2219,
1655, 1600, 1520, 1489, 1447, 1308, 1261, 1178, 1108, 1032, 852, 810,
967, 899, 874, 804, 739, 681 cmꢂ1
.
732, 639 cmꢂ1
.
4.2.10. 2-Nitrobiphenyl16c (4a)
4.2.16. 2-Cyanobiphenyl16c (6a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 4a as a yel-
low liquid; Rf (10% ethyl acetate in petroleum ether) 0.40; dH
(400 MHz, CDCl3): 7.84 (dd, 1H, J¼8.0, 1.2 Hz, CHar), 7.60 (td, 1H,
J¼7.6, 1.2 Hz, CHar), 7.38–7.48 (m, 5H, CHar), 7.29–7.32 (m, 2H, CHar);
dC (100 MHz, CDCl3): 149.3, 137.3, 136.3, 132.2, 131.9, 128.6, 128.2,
128.1, 127.8, 124.0; nmax (liquid film): 3062, 3031, 2868, 1605, 1568,
1525, 1472, 1452, 1354, 1306, 1162, 1142, 1093, 1075, 917, 852, 782,
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 6a as a pale
yellow liquid; Rf (10% ethyl acetate in petroleum ether) 0.43; dH
(400 MHz, CDCl3): 7.74–7.76 (m, 1H, CHar), 7.61–7.64 (m, 1H, CHar),
7.40–7.56 (m, 7H, CHar); dC (100 MHz, CDCl3): 145.5, 138.1, 133.7,
132.8, 130.1, 128.7, 127.5, 118.7, 111.3; nmax (liquid film): 3062, 3031,
2925, 2223, 1595, 1562, 1476, 1450, 1433, 1267, 1075, 1048, 1008,
777, 758, 734, 699 cmꢂ1
.
770, 740, 698, 666 cmꢂ1
.
4.2.17. 4-Trifluoromethylbiphenyl17a,g (7a)
4.2.11. 4-Methoxy-20-nitrobiphenyl15c (4b)
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 7a as a white solid; Mp 67–68 ꢀC
(lit. 70–70.5 ꢀC); Rf (10% ethyl acetate in petroleum ether) 0.75; dH
(400 MHz, CDCl3): 7.68 (s, 4H, CHar), 7.57–7.60 (m, 2H, CHar), 7.44–
7.48 (m, 2H, CHar), 7.37–7.41 (m, 1H, CHar); dC (100 MHz, CDCl3):
144.7, 139.7, 129.0, 128.2, 127.4, 127.2, 125.7, 125.7, 122.9; nmax (KBr):
3081, 2930, 1685, 1612, 1568, 1488, 1453, 1402, 1335, 1279, 1166,
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 4b as a yel-
low liquid; Rf (10% ethyl acetate in petroleum ether) 0.30; dH
(400 MHz, CDCl3): 7.80 (d, 1H, J¼7.8 Hz, CHar), 7.57–7.61 (m, 1H,
CHar), 7.42–7.46 (m, 2H, CHar), 7.24–7.27 (m, 2H, CHar), 6.94–6.97
(m, 2H, CHar), 3.85 (s, 3H, OCH3); dC (100 MHz, CDCl3): 159.6, 149.4,
135.8, 132.1, 131.9, 129.4, 129.1, 127.7, 124.0, 114.2, 55.3; nmax (liquid
film): 3065, 3034, 2959, 2934, 1612, 1579, 1522, 1476, 1441, 1412,
1356, 1295, 1254, 1091, 1017, 1000, 853, 832, 804, 781, 752,
1120, 1076, 1009, 844, 767, 728, 690, 638, 600 cmꢂ1
.
4.2.18. 4-Methoxy-40-trifluoromethylbiphenyl17b (7b)
728 cmꢂ1
.
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 7b as
a white solid; Mp 119–120 ꢀC (lit. 124.1–124.5 ꢀC); Rf (10% ethyl
acetate in petroleum ether) 0.50; dH (400 MHz, CDCl3): 7.64 (s, 4H,
CHar), 7.53 (d, 2H, J¼8.8 Hz, CHar), 7.00 (d, 2H, J¼8.8 Hz, CHar), 3.85
(s, 3H, OCH3); dC (100 MHz, CDCl3): 159.8, 144.2, 132.1, 128.3, 126.8,
125.7, 125.6, 123.0, 114.4, 55.3; nmax (KBr): 2923, 2845, 1686, 1605,
1530,1501,1461,1401,1335,1297,1277,1258,1203,1169,1073,1034,
4.2.12. 4-Methyl-20-nitrobiphenyl16c (4c)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 4c as a yellow
liquid; Rf (10% ethyl acetate in petroleum ether) 0.43; dH (400 MHz,
CDCl3): 7.83 (d, 1H, J¼8.1 Hz, CHar), 7.59–7.63 (m, 1H, CHar), 7.43–
7.48 (m, 2H, CHar), 7.21–7.26 (m, 4H, CHar), 2.41 (s, 3H, CH3); dC
(100 MHz, CDCl3): 149.3, 138.1, 136.2, 134.3, 132.2, 131.9, 129.4,
127.9, 127.7, 124.0, 21.2; nmax (liquid film): 3027, 2921, 2867, 1613,
1566, 1525, 1475, 1355, 1305, 1283, 1041, 853, 819, 781, 749, 721,
1010, 829, 815, 702 cmꢂ1
.
4.2.19. 4-Methyl-40-trifluoromethylbiphenyl17b,h (7c)
704, 656, 639 cmꢂ1
.
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 7c as a white solid; Mp 123–
124 ꢀC (lit.121.2–121.3 ꢀC); Rf (10% ethyl acetate in petroleum ether)
0.73; dH (400 MHz, CDCl3): 7.67 (s, 4H, CHar), 7.49 (d, 2H, J¼8.3 Hz,
CHar), 7.27 (d, 2H, J¼7.8 Hz, CHar), 2.40 (s, 3H, CH3); dC (100 MHz,
CDCl3): 144.6, 138.1, 136.8, 129.7, 129.7, 127.2, 127.1, 127.0, 125.7,
123.0, 21.1; nmax (KBr): 3033, 2923, 2862, 1656, 1612, 1564, 1538,
1500, 1398, 1328, 1274, 1172, 1130, 1072, 1008, 851, 811, 738,
4.2.13. 4-Cyanobiphenyl16e (5a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 5a as a white
solid; Mp 84–85 ꢀC (lit. 86–87 ꢀC); Rf (10% ethyl acetate in petro-
leum ether) 0.35; dH (400 MHz, CDCl3): 7.65–7.72 (m, 4H, CHar),
7.56–7.58 (m, 2H, CHar), 7.38–7.48 (m, 3H, CHar); dC (100 MHz,
CDCl3): 145.6, 139.1, 132.5, 129.0, 128.6, 127.6, 127.2, 118.9, 110.8;
nmax (KBr): 3064, 2220, 1687, 1598, 1478, 1399, 1176, 1115, 1076,
702 cmꢂ1
.
1005, 843, 768, 696 cmꢂ1
.
4.2.20. 4-Benzoylbiphenyl17c (8a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 8a as a white
solid; Mp 101–102 ꢀC (lit. 103.2–106.2 ꢀC); Rf (10% ethyl acetate in
petroleum ether) 0.37; dH (400 MHz, CDCl3): 7.90 (d, 2H, J¼8.3 Hz,
CHar), 7.83 (d, 2H, J¼8.1 Hz, CHar), 7.70 (d, 2H, J¼8.3 Hz, CHar), 7.65
(d, 2H, J¼7.1 Hz, CHar), 7.57–7.61 (m, 1H, CHar), 7.45–7.51 (m, 4H,
CHar), 7.37–7.41 (m, 1H, CHar); dC (100 MHz, CDCl3): 196.3, 145.2,
4.2.14. 4-Cyano-40-methoxybiphenyl15c (5b)
The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 5b as a white
solid; Mp 97–98 ꢀC (lit. 103–104 ꢀC); Rf (10% ethyl acetate in pe-
troleum ether) 0.20; dH (400 MHz, CDCl3): 7.60–7.68 (m, 4H, CHar),
7.51 (d, 2H, J¼8.8 Hz, CHar), 6.98 (d, 2H, J¼8.8 Hz, CHar), 3.85 (s, 3H,

5770
M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
139.9, 137.7, 136.2, 132.3, 130.7, 130.0, 128.9, 128.3, 128.2, 127.3,
a colorless liquid; Rf (10% ethyl acetate in petroleum ether) 0.63; dH
(400 MHz, CDCl3): 7.20–7.26 (m, 6H, CHar), 6.95 (d, 2H, J¼8.8 Hz,
CHar), 3.85 (s, 3H, OCH3), 2.27 (s, 3H, CH3); dC (100 MHz, CDCl3):
158.5, 141.5, 135.5, 134.3, 130.2, 129.9, 126.9, 125.7, 113.5, 55.3, 20.5;
nmax (liquid film): 3059, 3016, 2952, 2933, 2834, 1612, 1578, 1515,
1483, 1462,1441,1409,1379,1293,1267,1243,1176,1119,1106,1038,
126.9; nmax (KBr): 3053, 2923, 2854, 1643, 1599, 1482, 1445, 1400,
1317, 1291, 1151, 1073, 968, 939, 851, 799, 759, 729, 693 cmꢂ1
.
4.2.21. 4-Benzoyl-40-methylbiphenyl17d (8b)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 8b as a white
solid; Mp 121–122 ꢀC (lit. 128–129 ꢀC);17e Rf (10% ethyl acetate in
petroleum ether) 0.45; dH (400 MHz, CDCl3): 7.78–7.85 (m, 4H,
CHar), 7.64–7.66 (m, 2H, CHar), 7.46–7.56 (m, 5H, CHar), 7.24–7.26
(m, 2H, CHar), 2.38 (s, 3H, CHar); dC (100 MHz, CDCl3): 196.4, 145.1,
138.1, 137.7, 137.0, 135.9, 132.3, 130.7, 129.9, 129.7, 128.2, 127.1, 126.7,
21.1; nmax (KBr): 3023, 2912, 1644, 1598, 1527, 1489, 1443, 1397,
1017, 834, 786, 761, 731 cmꢂ1
.
4.2.27. 4-Chlorobiphenyl17a (13a)
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 13a as a white solid; Mp 75–
76 ꢀC (lit. 77–78.5 ꢀC); Rf (10% ethyl acetate in petroleum ether)
0.75; dH (400 MHz, CDCl3): 7.47–7.55 (m, 4H, CHar), 7.32–7.44 (m,
5H, CHar); dC (100 MHz, CDCl3): 139.9, 139.6, 133.3, 128.9, 128.3,
127.5, 126.9; nmax (KBr): 3065, 2922, 1656, 1586, 1473, 1393, 1095,
1289, 1143, 1073, 999, 938, 853, 819, 787, 734, 692 cmꢂ1
.
4.2.22. 4-Carboethoxybiphenyl17a (9a)
1002, 831, 756, 686, 618 cmꢂ1
.
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 9a as a pale
yellow solid; Mp 48–49 ꢀC (lit. 48–49 ꢀC);17f Rf (10% ethyl acetate in
petroleum ether) 0.43; dH (400 MHz, CDCl3): 8.10 (d, 2H, J¼8.3 Hz,
CHar), 7.65 (d, 2H, J¼8.5 Hz, CHar), 7.61 (d, 2H, J¼7.1 Hz, CHar), 7.45
(t, 2H, J¼7.4 Hz, CHar), 7.38 (t, 1H, J¼7.3 Hz, CHar), 4.39 (q, 2H,
J¼7.2 Hz, OCH2CH3), 1.40 (t, 3H, J¼7.1 Hz, OCH2CH3); dC (100 MHz,
CDCl3): 166.5, 145.5, 140.0, 130.0, 129.2, 128.9, 128.1, 127.2, 127.0,
60.9, 14.3; nmax (KBr): 3069, 3028, 2986, 2930, 1704, 1604, 1478,
4.2.28. 4-Chloro-40-methoxybiphenyl17b (13b)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 13b as
a white solid; Mp 112–113 ꢀC (lit. 111.1–111.3 ꢀC); Rf (10% ethyl ac-
etate in petroleum ether) 0.45; dH (400 MHz, CDCl3): 7.44–7.50 (m,
4H, CHar), 7.36 (d, 2H, J¼8.6 Hz, CHar), 6.95 (d, 2H, J¼8.8 Hz, CHar),
3.84 (s, 3H, OCH3); dC (100 MHz, CDCl3): 159.3, 139.2, 132.6, 132.5,
128.8, 128.0, 127.9, 114.3, 55.3; nmax (KBr): 3009, 2962, 2935, 2838,
1654, 1603, 1522, 1483, 1394, 1287, 1257, 1197, 1130, 1097, 1036,
1450, 1401, 1373, 1280, 1192, 1110, 1019, 863, 751, 696 cmꢂ1
.
1008, 814, 731 cmꢂ1
.
4.2.23. 4-Carboethoxy-40-methylbiphenyl17a (9b)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 9b as
a white solid; Mp 75–76 ꢀC (lit. 80–80.5 ꢀC);18a Rf (10% ethyl acetate
in petroleum ether) 0.44; dH (400 MHz, CDCl3): 8.08 (d, 2H,
J¼8.6 Hz, CHar), 7.62 (d, 2H, J¼8.6 Hz, CHar), 7.51 (d, 2H, J¼8.3 Hz,
CHar), 7.25 (d, 2H, J¼8.1 Hz, CHar), 4.38 (q, 2H, J¼7.2 Hz, OCH2CH3),
2.40 (s, 3H, CH3), 1.40 (t, 3H, J¼7.2 Hz, OCH2CH3); dC (100 MHz,
CDCl3): 166.5, 145.4, 138.0, 137.1, 130.0, 129.6, 128.9, 127.1, 126.7,
60.9, 21.1, 14.3; nmax (KBr): 2955, 1704, 1605, 1528, 1491, 1446, 1397,
4.2.29. 4-Chloro-40-methylbiphenyl18d (13c)
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 13c as a white solid; Mp 116–
118 ꢀC; Rf (10% ethyl acetate in petroleum ether) 0.75; dH (400 MHz,
CDCl3): 7.47 (d, 2H, J¼8.8 Hz, CHar), 7.43 (d, 2H, J¼8.1 Hz, CHar), 7.36
(d, 2H, J¼8.6 Hz, CHar), 7.23 (d, 2H, J¼7.8 Hz, CHar), 2.38 (s, 3H, CH3);
dC (100 MHz, CDCl3): 139.5, 137.4, 137.0, 133.0, 129.6, 128.8, 128.1,
126.8, 21.1; nmax (KBr): 3023, 2917, 2853, 1516, 1478, 1391, 1184,
1089, 1000, 844, 807, 727, 601 cmꢂ1
.
1366, 1272, 1221, 1199, 1175, 1110, 1020, 861, 818, 768, 697 cmꢂ1
.
4.2.30. 3-Cyanobiphenyl18e (14a)
4.2.24. 4-Methoxy-40-methylbiphenyl18b (10a)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 14a as
a colorless liquid; Rf (10% ethyl acetate in petroleum ether) 0.40; dH
(400 MHz, CDCl3): 7.79–7.84 (m, 2H, CHar), 7.38–7.62 (m, 7H, CHar);
dC (100 MHz, CDCl3): 142.3, 138.8, 131.4, 130.6, 129.5, 129.1, 128.3,
127.0, 118.8, 112.9; nmax (liquid film): 3063, 3032, 2229, 1597, 1580,
1500, 1476, 1450, 1264, 1173, 1097, 1076, 1048, 1022, 895, 843, 802,
The crude product was purified on SiO2 by column chroma-
tography (0.25% ethyl acetate in petroleum ether) to give 10a as
a white solid; Mp 104–106 ꢀC (lit. 105–107 ꢀC);18c Rf (10% ethyl
acetate in petroleum ether) 0.62; dH (400 MHz, CDCl3): 7.51 (d, 2H,
J¼8.8 Hz, CHar), 7.45 (d, 2H, J¼7.8 Hz, CHar), 7.23 (d, 2H, J¼8.3 Hz,
CHar), 6.96 (d, 2H, J¼8.6 Hz, CHar), 3.84 (s, 3H, OCH3), 2.38 (s, 3H,
CH3); dC (100 MHz, CDCl3): 158.9, 137.9, 136.3, 133.7, 129.4, 127.9,
126.5, 114.1, 55.3, 21.0; nmax (KBr): 2956, 2918, 2855, 1607, 1531,
1499, 1443, 1400, 1321, 1288, 1251, 1219, 1182, 1136, 1038, 1015, 840,
757, 695 cmꢂ1
.
4.2.31. 3-Cyano-40-methoxybiphenyl16c (14b)
808 cmꢂ1
.
The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 14b as
a white solid; Mp 63–65 ꢀC; Rf (10% ethyl acetate in petroleum
ether) 0.25; dH (400 MHz, CDCl3): 7.74–7.80 (m, 2H, CHar), 7.47–7.57
(m, 4H, CHar), 6.97–7.00 (m, 2H, CHar), 3.84 (s, 3H, OCH3); dC
(100 MHz, CDCl3): 159.9,141.9,131.2,130.9,130.1,130.0,129.5,128.1,
118.9, 114.5, 112.8, 55.3; nmax (KBr): 3055, 2977, 2934, 2840, 2225,
1605, 1576, 1512, 1470, 1398, 1293, 1247, 1177, 1113, 1047, 1021, 836,
4.2.25. 4-Methoxy-30-methylbiphenyl17c,18b (11a)
The crude product was purified on SiO2 by column chroma-
tography (0.25% ethyl acetate in petroleum ether) to give 11a as
a white solid; Mp 48–49 ꢀC (lit. 48.1–49.5 ꢀC); Rf (10% ethyl acetate
in petroleum ether) 0.60; dH (400 MHz, CDCl3): 7.53 (d, 2H,
J¼8.8 Hz, CHar), 7.30–7.38 (m, 3H, CHar), 7.13 (d, 1H, J¼7.3 Hz, CHar),
6.97 (d, 2H, J¼8.8 Hz, CHar), 3.85 (s, 3H, OCH3), 2.42 (s, 3H, CH3); dC
(100 MHz, CDCl3): 159.0, 140.8, 138.2, 133.8, 128.6, 128.1, 127.5,
127.4, 123.8, 114.1, 55.3, 21.5; nmax (KBr): 3029, 2945, 2910, 2846,
1659, 1601, 1514, 1480, 1283, 1253, 1184, 1120, 1026, 896, 835, 784,
803, 690 cmꢂ1
.
4.2.32. 3-Cyano-40-methylbiphenyl19a (14c)
The crude product was purified on SiO2 by column chroma-
tography (1% ethyl acetate in petroleum ether) to give 14c as
a white solid; Mp 66–68 ꢀC; Rf (10% ethyl acetate in petroleum
ether) 0.43; dH (400 MHz, CDCl3): 7.83 (s, 1H, CHar), 7.77 (d, 1H,
J¼7.8 Hz, CHar), 7.58 (d, 1H, J¼7.6 Hz, CHar), 7.44–7.52 (m, 3H, CHar),
7.27 (d, 2H, J¼8.0 Hz, CHar), 2.39 (s, 3H, CH3); dC (CDCl3, 100 MHz):
690 cmꢂ1
.
4.2.26. 4-Methoxy-20-methylbiphenyl17b (12a)
The crude product was purified on SiO2 by column chroma-
tography (0.25% ethyl acetate in petroleum ether) to give 12a as

M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
5771
142.3, 138.4, 135.9, 131.2, 130.4, 129.8, 129.5, 126.8, 118.9, 112.8, 21.1;
nmax (KBr): 3033, 2917, 2860, 2225, 1666, 1603, 1570, 1472, 1388,
1320, 1263, 1170, 1040, 891, 826, 795, 686 cmꢂ1; HRMS(ESþ) for
(MþH) C14H12N, calcd 194.0970; found 194.0971.
4.2.38. 2-Phenylnaphthalene19b (18a)
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 18a as a white solid; Mp 103–
104 ꢀC (lit. 94–97 ꢀC); Rf (10% ethyl acetate in petroleum ether)
0.70; dH (400 MHz, CDCl3): 8.05 (s, 1H, CHar), 7.86–7.93 (m, 3H,
CHar), 7.72–7.77 (m, 3H, CHar), 7.47–7.53 (m, 4H, CHar), 7.37–7.40 (m,
1H, CHar); dC (100 MHz, CDCl3): 141.1, 138.5, 133.6, 132.6, 128.8,
128.4,128.2,127.6, 127.4, 127.3, 126.3,125.9,125.8,125.6; nmax (KBr):
3053,1624,1594, 1491,1451, 1358,1272,1204,1162, 1127,1074,1015,
4.2.33. 4-Methoxybiphenyl17a (15a)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 15a as
a white solid; Mp 84–86 ꢀC (lit. 86 ꢀC);18f Rf (10% ethyl acetate in
petroleum ether) 0.45; dH (400 MHz, CDCl3): 7.52–7.56 (m, 4H,
CHar), 7.41 (t, 2H, J¼7.6 Hz, CHar), 7.30–7.31 (m, 1H, CHar), 6.96–6.99
(m, 2H, CHar), 3.85 (s, 3H, OCH3); dC (100 MHz, CDCl3): 159.1, 140.8,
133.7, 128.7, 128.1, 126.7, 126.6, 114.2, 55.3; nmax (KBr): 3034, 3000,
2960, 2930, 2836, 1604, 1521, 1484, 1280,1248, 1196, 1036, 834, 759,
947, 891, 858, 820, 756, 687 cmꢂ1
.
4.2.39. 2-(4-Methoxyphenyl)naphthalene19b (18b)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 18b as
a white solid; Mp 130–132 ꢀC (lit. 135–137 ꢀC); Rf (10% ethyl acetate
in petroleum ether) 0.50; dH (400 MHz, CDCl3): 7.98 (s, 1H, CHar),
7.83–7.89 (m, 3H, CHar), 7.71 (dd,1H, J¼8.6,1.7 Hz, CHar), 7.66 (d, 2H,
J¼8.8 Hz, CHar), 7.43–7.50 (m, 2H, CHar), 7.02 (d, 2H, J¼8.6 Hz, CHar),
3.86 (s, 3H, OCH3); dC (100 MHz, CDCl3): 159.2, 138.1, 133.7, 133.6,
132.2, 128.4, 128.3, 128.0, 127.6, 126.2, 125.6, 125.4, 125.0, 114.3,
55.3; nmax (KBr): 3050, 2954, 2837, 1606, 1521, 1467, 1439, 1282,
687 cmꢂ1
.
4.2.34. 3-Acetylbiphenyl17c,i (16a)
The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 16a as
a colorless liquid; Rf (10% ethyl acetate in petroleum ether) 0.37; dH
(400 MHz, CDCl3): 8.17–8.18 (m, 1H, CHar), 7.90–7.93 (m, 1H, CHar),
7.76–7.79 (m, 1H, CHar), 7.59–7.62 (m, 2H, CHar), 7.43–7.54 (m, 3H,
CHar), 7.35–7.39 (m, 1H, CHar), 2.64 (s, 3H, COCH3); dC (100 MHz,
CDCl3): 198.1, 141.6, 140.1, 137.5, 131.7, 129.0, 128.9, 127.8, 127.1,
126.9, 26.7; nmax (liquid film): 3060, 3032, 2923, 1684, 1595, 1478,
1451, 1419, 1356, 1297, 1235, 1079, 1020, 960, 906, 803, 758,
1253, 1201, 1183, 1038, 967, 949, 894, 865, 830,790 cmꢂ1
.
4.2.40. 2-(4-Methylphenyl)naphthalene19b (18c)
The crude product was purified on SiO2 by column chroma-
tography (petroleum ether) to give 18c as a white solid; Mp 85–
86 ꢀC (lit. 75–78 ꢀC); Rf (10% ethyl acetate in petroleum ether) 0.70;
dH (400 MHz, CDCl3): 8.03 (s, 1H, CHar), 7.85–7.91 (m, 3H, CHar),
7.73–7.75 (m, 1H, CHar), 7.63 (d, 2H, J¼8.0 Hz, CHar), 7.45–7.51 (m,
2H, CHar), 7.30 (d, 2H, J¼8.0 Hz, CHar), 2.43 (s, 3H, CH3); dC
(100 MHz, CDCl3): 138.4, 138.2, 137.1, 133.7, 132.4, 129.6, 128.3,
128.1, 127.6, 127.2, 126.2, 125.7, 125.5, 125.4, 21.1; nmax (KBr): 3052,
3020, 2919, 2855, 2371, 2339, 1598, 1497, 1429, 1344, 1269, 1213,
697 cmꢂ1
.
4.2.35. 3-Acetyl-40-methoxybiphenyl (16b)
The crude product was purified on SiO2 by column chroma-
tography (3% ethyl acetate in petroleum ether) to give 16b as
a white solid; Mp 54–56 ꢀC; Rf (10% ethyl acetate in petroleum
ether) 0.23; dH (400 MHz, CDCl3): 8.12 (t, 1H, J¼1.7 Hz, CHar), 7.86
(d, 1H, J¼7.8 Hz, CHar), 7.73 (d, 1H, J¼7.6 Hz, CHar), 7.54 (d, 2H,
J¼8.8 Hz, CHar), 7.49 (t, 1H, J¼7.8 Hz, CHar), 6.98 (d, 2H, J¼8.8 Hz,
CHar), 3.84 (s, 3H, OCH3), 2.63 (s, 3H, COCH3); dC (100 MHz, CDCl3):
198.2, 159.5, 141.2, 137.5, 132.6, 131.3, 128.9, 128.2, 126.6, 126.4,
114.3, 55.3, 26.8; nmax (KBr): 3001, 2959, 2933, 2837, 1684, 1608,
1516, 1478, 1434, 1356, 1297, 1247, 1180, 1139, 1045, 1025, 960, 909,
1111, 1016, 947, 893, 857, 811, 746 cmꢂ1
.
Acknowledgements
The authors thank Department of Science and Technology (DST),
New Delhi and IIT Kanpur for financial support. D.N.J thanks CSIR,
New Delhi, while D.B. thanks IIT Kanpur for research fellowships.
835, 796, 692 cmꢂ1
227.1072; found 227.1077.
;
HRMS(ESþ) for (MþH) C15H15O2, calcd
References and notes
4.2.36. 3-Acetyl-40-methylbiphenyl (16c)
1. Selected reviews on coupling reactions, see: (a) Nicolaou, K. C.; Bulger, P. G.;
Sarlah, D. Angew. Chem., Int. Ed. 2005, 44, 4442; (b) Hassan, J.; Sevignon, M.;
Gozzi, C.; Schulz, E.; Lemaire, M. Chem. Rev. 2002, 102, 1359; (c) Kotha, S.; Lahiri,
K.; Kashinath, D. Tetrahedron 2002, 58, 9633; (d) Christmann, U.; Vilar, R. Angew.
Chem., Int. Ed. 2005, 44, 366; (e) Corbet, J.-P.; Mignani, G. Chem. Rev. 2006, 106,
2651; (f) Rouhi, A. M. Chem. Eng. News 2004, 82, 49.
2. (a) Gonzalez-Bobes, F.; Fu, G. C. J. Am. Chem. Soc. 2006, 128, 5360; (b) Billingsley,
K. L.; Anderson, K. W.; Buchwald, S. L. Angew. Chem., Int. Ed. 2006, 45, 3484; (c)
Barder, T. E.; Walker, S. D.; Martinelli, J. R.; Buchwald, S. L. J. Am. Chem. Soc.
2005, 127, 4685; (d) Buszek, K. R.; Brown, N. Org. Lett. 2007, 9, 707; (e)
Molander, G. A.; Yokoyama, Y. J. Org. Chem. 2006, 71, 2493; (f) Molander, G. A.;
Felix, L. A. J. Org. Chem. 2005, 70, 3950; (g) Seganishi, W. M.; Deshong, P. Org.
Lett. 2006, 8, 3951.
3. Molander, G. A.; Ellis, N. Acc. Chem. Res. 2007, 40, 275.
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therein.
5. (a) Perez, I.; Sestelo, J. P.; Sarandeses, L. A. Org. Lett. 1999, 1, 1267; (b) Perez, I.;
Sestelo, J. P.; Sarandeses, L. A. J. Am. Chem. Soc. 2001, 123, 4155; (c) Pena, M. A.;
Sestelo, J. P.; Sarandeses, L. A. J. Org. Chem. 2007, 72, 1271.
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2001.
7. (a) Finet, J.-P. Chem. Rev. 1989, 89, 1487; (b) Moiseev, D. V.; Malysheva, Y. B.;
Shavyrin, A. S.; Kurskii, Y. A.; Gushchin, A. V. J. Organomet. Chem. 2005, 690,
3652; (c) Tsubrik, O.; Maeorg, U.; Sillard, R.; Ragnarsson, U. Tetrahedron 2004,
60, 8363; (d) Suzuki, H.; Ikegami, T.; Matano, Y. Synthesis 1997, 249.
8. (a) Ohe, T.; Tanaka, T.; Kuroda, M.; Cho, C. S.; Ohe, K.; Uemura, S. Bull. Chem. Soc.
Jpn. 1999, 72, 1851 and references cited therein; (b) Wada, M.; Natsume, S.;
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The crude product was purified on SiO2 by column chroma-
tography (2% ethyl acetate in petroleum ether) to give 16c as
a white solid; Mp 41–43 ꢀC; Rf (10% ethyl acetate in petroleum
ether) 0.40; dH (400 MHz, CDCl3): 8.09–8.10 (m, 1H, CHar), 7.82–
7.85 (m, 1H, CHar), 7.69–7.71 (m, 1H, CHar), 7.43–7.47 (m, 3H,
CHar), 7.18–7.25 (m, 2H, CHar), 2.58 (s, 3H, COCH3), 2.33 (s, 3H,
CH3); dC (100 MHz, CDCl3): 198.2, 141.6, 137.7, 137.5, 137.2, 131.5,
129.6, 129.0, 127.0, 126.9, 126.7, 26.8, 21.1; nmax (KBr): 3025, 2923,
2856, 1694, 1578, 1513, 1480, 1356, 1298, 1234, 1020, 823, 797,
695 cmꢂ1; HRMS(ESþ) for (MþH) C15H15O, calcd 211.1123; found
211.1124.
4.2.37. 4-Fluoro-40-methoxybiphenyl17b (17a)
The crude product was purified on SiO2 by column chroma-
tography (0.5% ethyl acetate in petroleum ether) to give 17a as
a white solid; Mp 82–84 ꢀC (lit. 87.3–87.8 ꢀC); Rf (10% ethyl ac-
etate in petroleum ether) 0.45; dH (400 MHz, CDCl3): 7.45–7.50
(m, 4H, CHar), 7.09 (t, 2H, J¼8.8 Hz, CHar), 6.96 (d, 2H, J¼8.8 Hz,
CHar), 3.84 (s, 3H, OCH3); dC (100 MHz, CDCl3): 162.0 (d,
J¼243.6 Hz), 159.1, 136.9, 132.8, 128.2 (d, J¼8.2 Hz), 128.0, 115.5
(d, J¼21.4 Hz), 114.2, 55.3; nmax (KBr): 3067, 3014, 2924, 2849,
1601, 1494, 1326, 1289, 1234, 1182, 1157, 1127, 1036, 1013, 826,
789 cmꢂ1
.

5772
M.L.N. Rao et al. / Tetrahedron 64 (2008) 5762–5772
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1 equiv of electrophilic reagents, see: (a) Rao, M. L. N.; Shimada, S.; Tanaka, M.
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