RETRACTED ARTICLE: Metal catalyst-free Suzuki-type coupling reaction in water

Article abstract of DOI:10.1016/j.tet.2006.03.096

The catalyst-free Suzuki-type coupling reaction of sodium tetraphenylborate with iodanes was achieved in good yields in water at room temperature. Similarly, the coupling of sodium tetraphenylborate with iodonium salts easily occurred in acidic water medium at 50 °C in good yields. Both coupling reactions were also promoted by microwave irradiation in water in short time.

Full text of DOI:10.1016/j.tet.2006.03.096

Tetrahedron 62 (2006) 5603–5607
Metal catalyst-free Suzuki-type coupling reaction in water
*
Jie Yan, Hongwei Jin and Shang Shan
College of Chemical Engineering and Materials Sciences, Zhejiang University of Technology, Hangzhou 310032, Zhejiang, PR China
Received 28 December 2005; revised 30 March 2006; accepted 31 March 2006
Available online 2 May 2006
Abstract—The catalyst-free Suzuki-type coupling reaction of sodium tetraphenylborate with iodanes was achieved in good yields in water at
ꢀ
room temperature. Similarly, the coupling of sodium tetraphenylborate with iodonium salts easily occurred in acidic water medium at 50 C in
good yields. Both coupling reactions were also promoted by microwave irradiation in water in short time.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
triflates affording products in excellent yields under mild re-
action conditions. Using hypervalent iodonium compounds
4
The Suzuki reaction is one of the most versatile and utilized
reactions for the selective construction of carbon–carbon
bonds, in particular for the formation of biaryls. For the
as alternative for aryl halides and triflates, we investigated
the coupling reaction of them with sodium tetraphenyl-
borate. Here we would like to report the metal catalyst-free
Suzuki-type coupling reaction of sodium tetraphenylborate
with hypervalent iodonium compounds in water.
1
development of improved conditions for the Suzuki reaction,
a wide range of metal complexes have been used as catalysts
in these coupling reactions, attention has particularly been
focused on palladium. Recently, N. E. Leadbeater and
M. Marco first reported a catalyst-free Suzuki coupling reac-
2. Results and discussion
2
tion, in which aryl halides reacted with arylboronic acids
under microwave irradiation without catalyst and afforded
biaryls in good yields (Fig. 1). It was also reported that
sodium tetraphenylborate could be used in place of phenyl-
boronic acid as a phenylating agent in the reaction. Due to
the development of pressure and the need for specialized
sealed vessels for this method, the development of mild
and efficient catalyst-free reaction conditions are required.
2.1. The coupling reaction of sodium tetraphenylborate
with iodanes in water
At the beginning, a readily available iodane, hydroxy(tosyl-
oxy)iodobenzene, referred to as Koser’s reagent was used
5
to couple with sodium tetraphenylborate in water at room
temperature, the product of a biphenyl in good yield was
obtained after the mixture was stirred for a short period of
time (Scheme 1). To determine suitable reaction conditions,
a series of experiments were performed on the coupling of
sodium tetraphenylborate (1) with Koser’s reagent (2a) to
form biphenyl (4a), we found that when 2 equiv of 1 were
used to react with 2a in water for 0.5 h at room temperature,
nearly quantitative 4a was formed. Under the optimal reac-
tion conditions, we checked the reactions of a series of
typical iodanes stable in water with sodium tetraphenyl-
In order to improve and extend the scope of this reaction,
especially to improve the coupling reaction using sodium
tetraphenylborate as a phenylating agent, we focused our
attention on hypervalent iodonium compounds. As powerful
electrophilic reagents, hypervalent iodine compounds, in
particular, iodonium salts have found synthetic application
3
in the reactions with various nucleophiles, they have also
been used in Suzuki reaction to replace aryl halides and
6
borate (Scheme 2), the results were summarized in Table 1.
X
B(OH)2 Microwave, TBAB
H O, 150°C, Na CO
R
+ R1
OH
H2O
R.T.
2
2
3
R
R1
Ph4BNa + Ph
I
Ph Ph
OTs
X=Br, I
Figure 1.
Scheme 1.
Scheme 2.
X
Y
H O
2
Ph4BNa + Ar I
Ph Ar
Keywords: Suzuki-type reaction; Sodium tetraphenylborate; Iodanes; Iodo-
nium salts; Microwave irradiation.
Corresponding author. Fax: +86 571 88320238; e-mail: jieyan87@
hotmail.com
R.T.
1
2
4
*
0
040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.03.096

5604
J. Yan et al. / Tetrahedron 62 (2006) 5603–5607
Table 1. The results of the Suzuki reaction of sodium tetraphenylborate with
iodanes
efficient acid and the reaction of 4 equiv of sodium tetra-
phenylborate, 2 equiv of p-TsOH, and 1 equiv of diphenyl-
iodonium chloride in water at 50 C for 30 min afforded
biphenyl in 95% yield. We extended this protocol to other
iodonium salts, the symmetrical and unsymmetrical biaryls
were readily available in high yields as shown in Scheme 3
and the results were summarized in Table 2.
a
ꢀ
Entry
1
Iodane
Product
Yield (%)
2a
4a
97
OH
Ph–Ph
Ph
I
OTs
2
b
2
3
4a
4a
78
90
PhI(OAc)
2
p-TsOH
2
c
Ph4BNa + Ar I Ar X
+
-
1
2
Ph Ar
PhI(OCOCF
3
)
2
H O, 50°C
2
2
d
1
3
4
+
Ph–I –O–I –Ph
+
4
4a
91
ꢁ
Scheme 3.
2
BF
4
2
e
b
5
6
7
4a
4b
55
From Table 2, it was shown that except iodonium salt 3c
entry 3), all iodonium salts worked well in the reaction pro-
viding products in good to excellent yields. Iodonium salt
f with electron-withdrawing substituent in phenyl gave
a somewhat lower yield product 4g (entry 6) than electron-
rich phenyliodonium salts 3b, 3d, and 3e (entries 2, 4, and
PhI]O
(
2
f
H
99
47
p-MeO–C
6
4
I(OAc)
2
6 4
p-MeO–C H –Ph
3
2g
4c
p-Cl–C
6
H
4
I(OAc)
2
6 4
p-Cl–C H –Ph
2h
4d
5
). It was also observed that the anions of iodonium salts
OH
I
O
Ph
OH
affected the yield greatly: with 3b the reaction was com-
pleted after only 0.5 h affording 4e in 92% yield (entry 2);
when 3h was used in place of 3b under the same reaction
conditions, the reaction was not completed even after 28 h
and the product was obtained in poor 29% yield. To try to im-
prove the yield, we increased the amount of acid to 6 equiv
and found that the coupling reaction was completed after
8
90
84
C
O
C
O
2
i
9
OH
I
4c
p-Cl-C6H4
1
h, giving the desired product in a much improved 78%
OTs
yield (entry 8). Similarly, 3i was also mixed with 6 equiv
of p-TsOH and 4 equiv of 1, the reaction could give 72%
product (entry 9), compared to a yield of 20% after a reaction
time of 35 h under the standard conditions. With a tosylate
iodonium salt 3g, the reaction time was somewhat longer
a
Isolated yields.
The reaction was run with sodium tetraphenylborate (2 equiv), iodosyl-
benzene (1 equiv), and p-TsOH (2 equiv) in water for 0.5 h.
b
It was shown that when Ar was a phenyl with electron-donat-
ing group, the yield of 4b was almost quantitative (entry 6)
and when Ar was a phenyl with electron-withdrawing group,
the yields of 4c were somewhat lower (entries 7 and 9) com-
pared to 4b (entry 6) and 4a (entry 1), respectively. When
iodosylbenzene (2e) was treated with 1 under the same reac-
tion conditions, the reaction did not occur even when the
reaction mixture was stirred for longer time at room temper-
ature or in heating conditions, but after adding 2 equiv of
Table 2. The results of the coupling reaction of sodium tetraphenylborate
with iodonium salts
Entry
Iodonium salt
Product
Time Yield
(h)
a
(%)
3
a
Ph I Cl
1
2
3
4
5
6
+
ꢁ
4a
4e
0.5
95
2
3
b
+
I Br
ꢁ
0.5
1
92
61
94
92
80
(
6
p-Me–C H
4
)
2
p-Me–C
4f
p-Br–C
6
H
4
–Ph
p-TsOH and stirred for 0.5 h, product 4a was obtained in
5% yield.
3
c
7
5
+
I Br
ꢁ
(
p-Br–C
6
H
4
)
2
6 4
H
–Ph
3
d
+
2.2. The coupling reaction of sodium tetraphenylborate
with iodonium salts in acidic water
ꢁ
6 4
p-Me–C H –I –PhBr
4e
1
3
H
e
+
–I –PhBr
ꢁ
4b
4g
1
p-MeO–C
6
4
Analogous to iodanes, iodonium salts have high reactivity to
sodium tetraphenylborate. However, we found that the cata-
lyst-free Suzuki reaction did not occur when iodonium salts
were used to react with sodium tetraphenylborate in water
in the presence or absence of base at room temperature or
higher temperatures. Then, we explored the coupling reac-
tion in acidic conditions, a quite different result was ob-
3
f
+ ꢁ
I Br
1
(
m-NO
2
–C
6
H
4
)
2
m-NO
2
6 4
–C H –Ph
3
g
4h
7
8
2
81
I+
PhOTs-
Ph
S
S
3h
b
78
+
I BF
ꢁ
4e
1
2
tained: the mixture of diphenyliodonium chloride (3a) with
ꢀ
(p-Me–C
6
H
4
)
2
4
1
was only stirred for a short time at 50 C in acidic water,
3i
(p-MeO–C
b
72
9
+
I BF
ꢁ
4b
a product of biphenyl (4a) was obtained in good yield.
Prompted by the result, a series of experiments were per-
formed on the coupling of 1 with 3a to determine the suitable
reaction conditions. It was found that p-TsOH was the most
6
H
4
)
2
4
a
Isolated yields.
The reaction was run with sodium tetraphenylborate (4 equiv), iodonium
salt (1 equiv), and p-TsOH (6 equiv) in water.
b

J. Yan et al. / Tetrahedron 62 (2006) 5603–5607
5605
and the yield was somewhat lower compared with 3a due to
the influence of the anion (entry 7).
afforded products 4 in good yields only in 2 min (Scheme 4,
Table 3).
2
.3. The coupling reaction of sodium tetraphenylborate
The reaction with iodanes needed shorter reaction time than
with iodonium salts meant that iodanes had more activity
towards sodium tetraphenylborate. However, it may be due
to their stability in water, in particular, under microwave
irradiation part of them could be decomposed.
with iodonium salts and iodanes under microwave
irradiation in water
Taking advantage of the above results, we further checked
the coupling reaction under microwave irradiation because
microwave-assisted organic syntheses have some advantages
such as fast reaction rates, high purity of products, and ease
3
. Conclusions
8
of manipulation. In particular, the microwave-irradiated
procedures in water medium for organic synthesis have
attracted considerable interest in recent years due to their
efficient and environmentally benign conditions.
In summary, we have presented here our observations that
the metal catalyst-free Suzuki-type coupling reaction of
sodium tetraphenylborate with hypervalent iodonium com-
pounds can be performed in water. The mechanism probably
9
We used diphenyliodonium chloride (3a) to investigate the
coupling reaction with sodium tetraphenylborate (1) under
microwave irradiation in water, we found that the coupling
was easy to be carried out and when the molar ratio of 1 to
involved first a nucleophilic substitution of acid radical of
iodonium salts or iodanes by Ph B , then, an intramolecular
ꢁ
4
coupling reaction was accompanied to yield biaryls as
shown by the coupling of sodium tetraphenylborate with
Koser’s reagent (Scheme 5). This coupling reaction pro-
vided fast and efficient method for preparation of biaryls,
it had some advantages such as mild reaction conditions,
simple procedure, and good yields. Furthermore, the scope
of the catalyst-free Suzuki coupling reactions could be
extended.
3
a reached 2:1, the best result of 90% biphenyl was afforded
ꢀ
under microwave irradiation for 4 min at 100 C. Under the
optimized conditions, the coupling reactions of iodonium
salts 3 with 1 were shown in Scheme 4 and the good results
were given in Table 3.
X
Y
Microwave
H O, 100°C
Ph4BNa + ArI Ar1X- or Ar
+
I
Ph Ar
2
OH
1
3
2
4
OH -NaOTs
Ph
I
Ph4BNa + Ph
I
Scheme 4.
OTs
Ph BPh3
Ph Ph + BPh3 + HIO
It was shown that most reactions could be completed in
4
1
min affording products in good to excellent yields (entries
–6). However, iodonium salt 3f with electron-withdrawing
Scheme 5.
substituent in phenyl only provided 4g in 37% yield after
min (entry 7). We also observed that the anions of iodo-
nium salts affected the yield strongly: with 3b the reaction
was completed after only 3 min and afforded 4e in 93% yield
(entry 2); when 3h was used in place of 3b under the same
reaction conditions, even after a prolonged reaction time
of 15 min, 4e was obtained in a poor 41% yield (entry 8).
5
4
. Experimental
4
.1. General
Mps were determined on a digital mp apparatus and were not
corrected. IR spectra were recorded on a FT-170 SX instru-
ment, H NMR spectra were measured on a Bruker AM-400
FT-NMR spectrometer, and Mass spectra were determined
on HP5989A mass spectrometer. Microwave reaction was
carried out with a single-mode cavity Sanle WHL70S-01
Microwave Synthesizer (Nanjing Sanle Microwave Equip-
ment Corporation). Iodonium salts were prepared according
1
Under the same reaction conditions, we found that iodanes
2) could react with sodium tetraphenylborate (1) and
(
Table 3. The results of the Suzuki reaction under microwave irradiation
a
Entry
Iodonium salt
and iodanes
Product
Time (min)
Yield (%)
10
to the literature procedures. Iodanes were prepared accord-
Sodium tetraphenyl-
5
,11
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
3a
3b
3c
3d
3e
3g
3f
3h
2a
2b
2c
2d
2e
2g
2h
4a
4e
4f
4
3
3
2
4
3
5
15
2
2
90
93
91
74
77
80
37
41
83
87
82
80
65
73
67
ing to the literature procedures.
borate is commercially available.
4e
4b
4h
4g
4e
4a
4a
4a
4a
4a
4c
4d
4.2. The general procedure for reaction of sodium
tetraphenylborate with iodanes in water
Sodium tetraphenylborate (1) (342 mg, 1.0 mmol) and
iodane (2) (0.5 mmol) were added in 5 mL of H O. The mix-
2
0
1
2
3
4
5
ture was stirred for 0.5 h at room temperature and quenched
with brine (5 mL). The mixture was extracted with diethyl
ether (20ꢂ3 mL), and the organic layer was dried over anhy-
1
1
1
2
drous MgSO , and then evaporated in vacuo. The crude
4
1
product was separated by a silica gel plate using hexane as
developer to afford the pure product 4 in good yields.
a
Isolated yield.

5606
J. Yan et al. / Tetrahedron 62 (2006) 5603–5607
ꢀ
16
4.3. The general procedure for reaction of sodium
tetraphenylborate with iodonium salts in water
4.4.7. m-Nitrobiphenyl (4g). Mp 56–58 C (lit. 58–
ꢀ
m, 1H), 8.11–8.23 (m, 1H), 8.40–8.45 (m, 1H); IR (KBr):
1
60 C). H NMR (CDCl ): d¼7.40–7.67 (m, 6H), 7.83–7.95
3
(
ꢁ
1
Sodiumtetraphenylborate(1) (137 mg, 0.4 mmol, 4.0 equiv),
iodonium salt (3) (0.1 mmol), and p-TsOH (38 mg,
n¼3064, 3036, 1536, 1362, 877, 772, 733 cm ; MS
+
(75 eV, EI) m/z (%): 199 (M , 100).
0
.2 mmol, 2.0 equiv) were added in 5 mL of H O. The mix-
2
ꢀ
4a 1
ture was stirred at 50 C until it was complete. After cooling
to room temperature the mixture was extracted with diethyl
ether (20ꢂ3 mL), and the organic layer was dried over anhy-
4.4.8. 2-Phenylthiophene (4h). Oil.
H NMR (CDCl3):
d¼7.10–7.13 (m, 1H), 7.30–7.34 (m, 2H), 7.37–7.40
(m, 1H), 7.46–7.49 (m, 2H), 7.62–7.66 (m, 2H); IR (KBr)
n¼3103, 3062, 3036, 1496, 1451, 747 cm ; MS (70 eV,
ꢁ
1
drous MgSO and evaporated in vacuo. The crude product
4
+
was separated by a silica gel plate using hexane as
developer to afford the pure product 4 in good yields.
EI) m/z (%): 160 (M , 100).
4
.4. The general procedure for reaction of sodium
Acknowledgements
tetraphenylborate with iodonium salts and iodanes
under microwave irradiation in water
Financial support from the Zhejiang Province Natural
Science Foundation of China (Project Y404016) and Zhe-
jiang Province Education Foundation of China (Project
Sodium tetraphenylborate (1) (513 mg, 1.5 mmol), iodo-
nium salt (3) or iodane (2) (0.75 mmol), and 5 mL of water
were added to a 50 mL flask with a condenser. The vessel
was placed inside the center of the microwave synthesizer
and then exposed to microwave irradiation (250 W) to heat
2
0040569) is greatly appreciated.
References and notes
ꢀ
it at reflux for 1–15 min at 100 C. After irradiation, the
reaction mixture was cooled to room temperature and
1. For recent reviews see: (a) Hassen, J.; Sevignon, M.; Gozzi, C.;
Schulz, E.; Lemaire, M. Chem. Rev. 2002, 102, 1359–1470; (b)
Kotha, S.; Lahiri, K.; Kashinath, D. Tetrahedron 2002, 58,
9633–9695; (c) Suzuki, A. J. Organomet. Chem. 1999, 576,
147–168; (d) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95,
extracted with diethyl ether (20ꢂ3 mL). The organic layer
was dried over anhydrous MgSO and evaporated in vacuo.
4
The crude product was separated by a silica gel plate using
hexane as eluent and the pure product 4 was afforded.
2
457–2483.
12
ꢀ ꢀ
1
4
.4.1. Biphenyl (4a). Mp 68–69 C (lit. 69–72 C). H
2
. (a) Leadbeater, N. E.; Marco, M. J. Org. Chem. 2003, 68, 5660–
5667; (b) Leadbeater, N. E.; Marco, M. Angew Chem., Int. Ed.
NMR (CDCl ): d¼7.32–7.36 (m, 2H), 7.42–7.46 (m, 4H),
3
7
7
.58–7.61 (m, 4H); IR (KBr): n¼3035, 1569, 1481,
ꢁ
2
003, 42, 1407–1409.
1
+
30 cm ; MS (70 eV, EI) m/z (%): 154 (M , 100).
3
. (a) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic: London, 1997; Varvoglis, A. Tetrahedron 1997,
13
ꢀ ꢀ
4
.4.2. p-Methoxybiphenyl (4b). Mp 86–87 C (lit. 88 C).
5
1
3, 1179–1255; (b) Stang, P. J.; Zhdankin, V. V. Chem. Rev.
996, 96, 1123–1178; (c) Zhdankin, V. V.; Stang, P. J. Chem.
Rev. 2002, 102, 2523–2584; (d) Wirth, T.; Hirt, U. H. Synthesis
1
H NMR (CDCl ): d¼3.83 (s, 3H), 6.96–6.98 (m, 2H), 7.27–
3
7
(
(
.31 (m, 1H), 7.38–7.42 (m, 2H), 7.51–7.55 (m, 4H); IR
ꢁ
1
KBr): n¼3068, 3033, 1262, 1035, 835, 761 cm ; MS
1
1
999, 1271–1287; (e) Kirschning, A. Eur. J. Org. Chem. 1998,
1, 2267–2274; (f) Ochiai, M. Chemistry of Hypervalent Com-
+
70 eV, EI) m/z (%): 184 (M , 100).
14
ꢀ ꢀ
pounds; Akibe, K., Ed.; VCH: New York, NY, 1999; Chapter
13, pp 359–387; Ochiai, M. J. Organomet. Chem. 2000, 611,
4
.4.3. p-Chlorobiphenyl (4c). Mp 74–75 C (lit. 77 C).
1
H NMR (CDCl ): d¼7.32–7.34 (m, 1H), 7.36–7.39
3
4
94–508; (g) Okuyama, T. Acc. Chem. Res. 2002, 35, 12–18;
h) Zhdankin, V. V.; Stang, P. J. Tetrahedron 1998, 54,
10927–10966; (i) Grushin, V. V. Chem. Soc. Rev. 2000, 29,
15–324.
(
(
7
m, 2H), 7.40–7.44 (m, 2H), 7.46–7.50 (m, 2H), 7.51–7.55
m, 2H); IR (KBr): n¼3067, 3035, 1479, 1099,1005, 833,
(
ꢁ1
+
60 cm ; MS (70 eV, EI) m/z (%): 188 (M , 100).
3
ꢀ
.4.4. 2-Biphenylcarboxylic acid (4d). Mp 108–110 C
4. (a) Kang, S.-K.; Lee, H.-W.; Jang, S.-B.; Ho, P.-S. J. Org.
Chem. 1996, 61, 4720–4724; (b) Kang, S.-K.; Yamagushi, Y.;
Kim, T.-H.; Ho, P.-S. J. Org. Chem. 1996, 61, 9082–9083; (c)
Bumagin, N. A.; Luzikova, E. V.; Sukhomlinova, L. I.; Tolstaya,
T. P.; Beletskaya, I. P. Russ. Chem. Bull. 1995, 44, 385–387; (d)
Kang, S.-K.; Jung, K.-Y.; Park, C.-H.; Jang, S.-B. Tetrahedron
Lett. 1995, 36, 8047–8050; (e) Moriarty, R. M.; Epa, W. R.;
Awashti, A. K. J. Am. Chem. Soc. 1991, 113, 6315–6317; (f)
Moriarty, R. M.; Epa, W. R. Tetrahedron Lett. 1992, 33,
4
(
7
1
5
ꢀ
.53 (m, 1H), 7.93 (m, 1H), 11.0 (br, 1H); IR (KBr):
1
lit. 112 C). H NMR (CDCl ): d¼7.30–7.39 (m, 7H),
3
ꢁ
1
n¼3400–2400 (br), 1700, 1685, 1306, 1296 cm ; MS
+
(
70 eV, EI) m/z (%): 198 (M , 100).
ꢀ
16
4
.4.5. p-Methylbiphenyl (4e). Mp 43–46 C (lit. 44–
ꢀ
m, 2H), 7.30–7.34 (m, 1H), 7.40–7.44 (m, 2H), 7.48–7.51
1
4
7 C). H NMR (CDCl ): d¼2.39 (s, 3H), 7.23–7.26
3
(
(
1
1
4095–4098; (g) Hinkle, R. J.; Poulter, G. T.; Stang, P. J.
J. Am. Chem. Soc. 1993, 115, 11626–11627.
m, 2H), 7.56–7.59 (m, 2H); IR (KBr): n¼3067, 3033,
ꢁ
1
488, 1007, 823, 766, 690 cm ; MS (70 eV, EI) m/z (%):
68 (M , 100).
+
5
. (a) Neiland, O.; Karek, B. J. Org. Chem. USSR (Engl. Trans.)
1970, 6, 889–891; (b) Koser, G. F.; Wettach, R. H. J. Org.
Chem. 1977, 42, 1476–1478.
ꢀ
16
4
8
(
1
.4.6. p-Bromobiphenyl (4f). Mp 83–85 C (lit. 85–
ꢀ
1
7 C). H NMR (CDCl ): d¼7.33–7.37 (m, 1H), 7.42–7.46
6. Yan, J.; Zhou, Z.-S.; Zhu, M. Tetrahedron Lett. 2005, 46, 8173–
8175.
7. Ueno, M.; Nabana, T.; Togo, H. J. Org. Chem. 2003, 68,
6424–6426.
3
m, 4H), 7.52–7.57 (m, 4H); IR (KBr): n¼3064, 3031,
ꢁ
1
477, 1393, 1080, 830, 767, 691 cm ; MS (75 eV, EI)
m/z (%): 234 (M+1), 233 (M , 13.3), 232 (100).
+

J. Yan et al. / Tetrahedron 62 (2006) 5603–5607
5607
8
. (a) Lidstrom, P.; Tierney, J.; Wathey, B.; Westman, J. Tetra-
hedron 2001, 57, 9225–9283; (b) Perreux, L.; Loupy, A. Tetra-
hedron 2001, 57, 9199–9223.
. Deshayes, S.; Liagre, M.; Loupy, A.; Luche, J.-L.; Petit, A.
Tetrahedron 1999, 55, 10851–10870.
theses; Wiley: New York, NY, 1973; Collect. Vol. V, p 658; (d)
Zhdankin, V. V.; Tykwinski, R.; Berglund, B.; Mullikin, M.;
Caple, R. J. Org. Chem. 1989, 54, 2609–2612; (e) Baker,
G. P.; Mann, F. G.; Shepperd, N.; Tetlow, A. J. J. Chem. Soc.
1965, 3721–3728.
9
1
1
0. (a) Beringer, F. M.; Drexler, M.; Gindler, E. M.; Lumpkin,
C. C. J. Am. Chem. Soc. 1953, 2705–2708; (b) Beringer,
F. M.; Drexler, M.; Gindler, E. M.; Lumpkin, C. C. J. Am.
Chem. Soc. 1959, 4321–4323; (c) Margida, A. J.; Koser,
G. F. J. Org. Chem. 1984, 49, 3643–3646.
1. (a) Pausacker, K. H. J. Chem. Soc. 1953, 107–109; (b)
Zhdankin, V. V.; Scheuller, M. C.; Stang, P. J. Tetrahedron
Lett. 1993, 34, 6853–6856; (c) Saltzman, H.; Sharefkin,
J. G. Org. Synth. 1963, 43, 60–61 and 658–659; Organic Syn-
12. Budavari, S.; O’Nell, M. J.; Smith, A.; Hevkelman, P. E.
The Merck Index, 11th ed.; Merck: Rahway, NJ, 1989;
p 3314.
13. Beil. 6, 674.
14. Hey, D. H.; Liang, K. S. Y.; Perkins, M. J.; Williams, G. H.
J. Chem. Soc. C 1967, 1153.
15. Gassmann, P. G.; Lumb, J. T.; Zalar, F. V. J. Am. Chem. Soc.
1967, 89, 946–952.
16. Beil. 5, 580, 582, 597.