Palladium-catalyzed cross-coupling of organolead compounds with organostannanes

Article abstract of DOI:10.1039/a802726i

The palladium-catalyzed cross-coupling of organolead triacetates with organostannanes has been accomplished in the presence of Pd₂(dba)₃·CHCl₃ (5 mol%) and NaOMe (5 equiv.) in MeOH-MeCN (1:1) under mild conditions.

Full text of DOI:10.1039/a802726i

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Palladium-catalyzed cross-coupling of organolead compounds with
organostannanes
Suk-Ku Kang,*† Hyung-Chul Ryu and Sang-Chul Choi
Department of Chemistry, Sung Kyun Kwan University, Natural Science Campus, Suwon 400-746, Korea
The palladium-catalyzed cross-coupling of organolead
triacetates with organostannanes has been accomplished in
(1:1) was most suitable. To avoid homocoupling, CuI (10
mol%) was added as a cocatalyst (Scheme 1).7
the presence of Pd
2
(dba)
3
·CHCl
3
(5 mol%) and NaOMe (5
Phenyllead triacetate 1a was reacted with vinyl tributylstan-
nane 2a in the presence of NaOMe (5 equiv.) using
Pd (dba) ·CHCl (5 mol%) and CuI (10 mol%) as catalysts in
2 3 3
equiv.) in MeOH–MeCN (1:1) under mild conditions.
The palladium-catalyzed cross-coupling of organostannanes
with aryl of vinyl halides and triflates, known as the Stille
MeOH–MeCN (1:1) at room temperature for 2 h to afford
styrene 3a as the sole product in 80% yield (entry 1, Table 1).
Under the same conditions the reaction of 1a with the
b-styrylstannane 2b gave the coupled product (E)-b-stilbene 3b
in 72% yield (entry 2). When phenyllead triacetate 1a was
treated with a-styrylstannane 2c, (E)-b-stilbene 3b was also
obtained as the sole product via the mechanism of cine
substitution in 40% yield (entry 3). For the alkynylstannane 2d,
the reaction with 1a gave the coupled product 3c in 79% yield
3
(entry 4). When the same reaction was conducted in CHCl as
1
reaction, has become a versatile tool in organic synthesis. Main
2
3
4
group metals such as lead(iv), bismuth and thallium have
been of limited use in cross-coupling reactions. Recently,
Pinhey reported the arylation, alkenylation and alkynylation of
2
organolead(iv) tricarboxylates with soft carbon nucleophiles.
As an alternative to organic electrophiles, hypervalent iodonium
compounds were employed in the cross-coupling with organo-
stannanes.5 However, the coupling reaction of organolead
compounds as electrophiles with organostannanes is not known.
Here we report the cross-coupling of organostannanes with
organolead(iv) compounds.
8
the only solvent, the coupled product 3c was obtained in 45%
9
yield along with the homocoupled product (30%). Treatment
of 2-furyl(tributyl)stannane 2e, 3-furyl(tributyl)stannane 2f, and
3-thienyl-substituted stannane 2g with p-methoxyphenyllead
Initially, we examined the cross-coupling of phenyllead
6
10
11
12
triacetate 1a with vinyl tributylstannane 2a to determine the
triacetate 1b afforded the substituted furans 3d, 3e and
thiophene 3f13 in 73, 70 and 85% yields, respectively (entries
5–7).‡ For the coupling of 1b with 2-furyl stannane 2e under the
same conditions without addition of CuI as catalyst, the coupled
product 3e was obtained in 60% yield after 7 h along with the
homocoupled product (25%). However, the addition of CuI (10
optimum reaction conditions. After series of fruitless experi-
ments, we found that the use of NaOMe as a base was crucial in
this coupling. Of the catalysts Pd
PdCl tested, Pd (dba) ·CHCl
CHCl was also effective, the solvent system MeOH–MeCN
2
3 3 2
(dba) ·CHCl , Pd(OAc) and
2
2
3
3
was the best. Even though
3
i
1
2
1
2
R Pb(OAc)3
+
R SnBu
R –R
3
1
2
3
1
a R1 = Ph
2a R2 = vinyl
3a R1 = Ph, R2 = vinyl
b R1 = p-MeOC6H4
b R2 = (E)-PhCH=CH b R1 = Ph, R2 = (E)-PhCH=CH
c R1 = 2,4-(MeO)2C6H3 c R2 = PhC(=CH2)
c R1 = Ph, R2 = PhC≡C
d R1 = p-MeOC6H4, R2 = 2-furyl
d R1 = 2-thienyl
d R2 = PhC≡C
e R2 = 2-furyl
f R2 = 3-furyl
g R2 = 2-thienyl
e R1 = p-MeOC6H4, R2 = 3-furyl
f R1 = p-MeOC H , R = 2-thienyl
2
6
4
g R1 = 2,4-(MeO) C H , R = 2-furyl
2
2
6 3
h R1 = 2,4-(MeO)2C6H3, R2 = 2-thienyl
i R1 = 2-thienyl R2 = (E)-PhCH=CH
3 3
Scheme 1 Reagents and conditions: i, Pd(dba) ·CHCl (5 mol%), CuI (10 mol%), NaOMe (5 equiv.), MeOH–MeCN (1 :1)
Table 1 Palladium-catalyzed cross-coupling of organostannanes with organolead triacetates
Organolead
compounds Organostannanes
Isolated
yield (%)a
Entry
T/°C
t/h
Product
1
2
3
4
5
6
7
8
9
1a
1a
1a
1a
1b
1b
1b
1c
1c
1d
2a
2b
2c
2d
2e
2f
2g
2e
2g
2b
room temp.
room temp.
60
room temp.
room temp.
60
2
2
3
2
2
2
2
3
3
2
3a
3b
3b
3c
3d
3e
3f
3g
3h
3i
80 (trace)
72 (trace)
40
79 (10)
73 (10)
70 (trace)
85 (10)
72 (trace)
73 (trace)
62 (10)
60
room temp.
room temp.
60
1
0
a
The yields in parentheses are the yields of the homocoupling products, which are easily separated by column chromatography.
Chem. Commun., 1998
1317

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mol%) improved the yield to 73% yield with reduced reaction
Wilkinson, Pergamon, New York, 1995, vol. 12, ch. 3, 4; V. Farina,
Pure Appl. Chem., 1996, 68, 73.
2 J. T. Pinhey, Aust. J. Chem., 1991, 44, 1353; J. T. Pinhey, Pure Appl.
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1970, 3, 338; R. C. Larock and H. Yang, Synlett, 1994, 748.
time (2 h) and reduced homocoupling (10%). The 2,4-dime-
thoxyphenyllead triacetate 1c14 was also coupled with 2-furyl
and 2-thienyl substituted stannanes 2e and 2g at room
temperature for 3 h to afford the coupled products 3g§ and 3h15
in 72 and 73% yields, respectively (entries 8 and 9). Finally,
3
4
1
6
2
-thienyllead triacetate 1d was reacted with (E)-b-styryl-
17
stannane 2b to give the coupled product 3i in 62% yield (entry
10). The results are summarized in Scheme 1 and Table 1.
Although the detailed mechanism for the role of NaOMe
5 R. M. Moriarty and W. R. Epa, Tetrahedron Lett., 1992, 33, 4095;
R. J. Hinkle, G. T. Poulter and P. J. Stang, J. Am. Chem. Soc., 1993, 115,
11626; S-K. Kang, H-W. Lee, J-S. Kim and S-C. Choi, Tetrahedron
Lett., 1996, 37, 3723; S-K. Kang, H-W. Lee, S-B. Jang, T-H. Kim and
J-S. Kim, Synth. Commun., 1996, 26, 4311.
remains to be elucidated, it is presumed that organolead
is formed18 and drives facile oxida-
trimethoxide RPb(OMe)
3
tive addition19 with Pd to give polar reactive intermediate
0
RPdPb(OMe) , which allows the transmetallation and coupling
3
6
J. Morgan and J. T. Pinhey, J. Chem. Soc., Perkin Trans. 1, 1990,
15.
to proceed under mild conditions
7
A typical procedure is as follows: To a stirred solution of
p-methoxylphenyllead triacetate 1b (140 mg, 0.28 mmol) and
NaOMe (77 mg, 1.42 mmol) in MeOH–MeCN (1:1, 3 ml) was
7
The CuCl-catalyzed homocoupling of vinyl- and aryl-lead diacetates
was reported by Pinhey see J. Morgan, C. J. Parkinson and J. T. Pinhey,
J. Chem. Soc., Perkin Trans. 1, 1994, 3361.
added Pd
mol%), followed by 2-thienyl(tributyl)stannane 2g (100 mg,
.27 mmol) via syringe at room temperature under N , and the
reaction mixture was stirred at 60 °C for 2 h and cooled to room
temperature. The reaction mixture was extracted with Et O (20
ml), washed three times with water, dried over anhydrous
MgSO and evaporated in vacuo. The crude product was
separated by SiO column chromatography (hexanes,
= 0.28) to afford the coupled product 3f (44 mg, 85%).
In conclusion, the palladium-catalyzed cross-coupling reac-
2
(dba)
3
·CHCl
3
(14 mg, 5 mol%) and CuI (5 mg, 10
8 K. Kikukawa, H. Umekawa and T. Matsuda, J. Organomet. Chem.,
1
1
986, 311, C44; G. Stork and R. C. A. Isaacs, J. Am. Chem. Soc., 1990,
12, 7399; C. A. Busacca, J. Swestock, R. E. Johnson, T. R. Bailey,
0
2
L. Musza and C. A. Rodger, J. Org. Chem., 1994, 59, 7553; V. Farina
and M. A. Hossain, Tetrahedron Lett., 1996, 37, 6997.
2
9
The substituted lead(iv) triacetates undergo homocoupling in the
2 3 3 3
presence of Pd (dba) ·CHCl (5 mol%) in CHCl at room temperature
for 10 min. See, S-K. Kang, U. Shivkumar, C. Ahn, S-C. Choi and
J-S. Kim, Synth. Commun., 1997, 27, 1893.
4
2
R
f
10 p-Methoxyphenyllead triacetate 1b was easily prepared from anisole by
treatment with lead tetraacetate. See R. P. Kozyrod and J. T. Pinhey,
Org. Synth., 1984, 62, 24.
tion of organolead triacetates with organostannanes was
achieved under mild conditions.
The authors wish to acknowledge the financial support of the
Korea Research Foundation in the Program Year 1997.
1
1
1 S. Pelter, M. Rowlands and G. Clements, Synthesis, 1987, 51.
2 R. H. Young, R. L. Martin, N. Chinh, C. Mallon and R. H. Kayser, Can.
J. Chem., 1972, 50, 932.
1
1
1
1
1
1
3 L. J. Baldwin, S. Pakray, R. N. Castle and M. L. Lee, J. Heterocyclic
Chem., 1985, 22, 1667.
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5 T. Sone, R. Yokoyama, Y. Okuyama and K. Sato, Bull. Chem. Soc. Jpn.,
Notes and References
†
‡
E-mail: skkang@chem.skku.ac.kr
Selected data for 3e: TLC, SiO
) 3.83 (s, 3 H), 6.65 (m, 1 H) 6.92 (m, 2 H), 7.42 (m, 3 H), 7.65 (s,
1
986, 59, 83.
6 H. C. Bell, J. R. Kalman, J. T. Pinhey and S. Sternhell, Aust. J. Chem.,
979, 32, 1521.
7 A. Kasahara, T. Izumi and T. Ogihara, J. Heterocyclic Chem., 1989, 26,
97.
2 f H
, hexanes, R = 0.36; d (400 MHz,
CDCl
H); nmax (neat)/cm2 3054, 2928, 1605, 1275; m/e (EI) 174 (100%), 159
75), 131 (45), 77 (40).
3
1
1
1
(
5
§
d
1
Selected data for 3g: TLC, SiO
(400 MHz, CDCl ) 3.96 (s, 3 H), 4.04 (s, 3 H), 6.59 (m, 1 H), 6.68 (m,
H), 6.70 (m, 1 H), 6.91 (m, 1 H), 7.54 (dd, 1 H), 7.87 (d, 1 H); nmax(neat)/
2 f
, EtOAc–hexanes (1:10), R = 0.37;
8 Recently, it was reported that the modification of ligands influences the
efficiency of the metal–metal exchange: C. J. Parkinson, J. T. Pinhey
and M. J. Stoermer, J. Chem. Soc., Perkin Trans. I, 1992, 1911.
9 The oxidative addition of organostannanes to a palladium(0) complex is
known: E. Shirakawa, H. Yoshida and T. Hiyama, Tetrahedron Lett.,
H
3
2
1
cm 3055, 2856, 1422, 1265, 896, 740; m/z (EI) 203 (100%), 188 (24), 161
41), 102 (119).
1
(
1
997, 38, 5177.
1
J. K. Stille, Angew. Chem., Int. Ed. Engl., 1986, 25, 508–524;
T. N. Mitchell, Synthesis, 1992, 803; V. Farina, in Comprehensive
Organometallic Chemistry II, ed. E. W. Abel, F. G. A. Stone and G.
Received in Cambridge, UK, 14th April 1998; 8/02726I
1318
Chem. Commun., 1998
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