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748
J . Org. Chem. 1998, 63, 5748-5749
P a lla d iu m -Ca ta lyzed Cou p lin g of Or ga n olea d
Com p ou n d s w ith Olefin s
Ta ble 1. Heck -Typ e Rea ction s of Or ga n olea d
Tr ia ceta tes w ith Olefin s
Suk-Ku Kang,* Sang-Chul Choi, Hyung-Chul Ryu, and
Tokutaro Yamaguchi
Department of Chemistry, Sung Kyun Kwan University,
Natural Science Campus, Suwon 440-746, Korea
Received March 30, 1998
The palladium-catalyzed coupling of organic electrophiles
(
i.e., halides and triflates) with alkenes (Heck-type coupling)1
is now recognized to be an extremely useful and convenient
method for the formation of carbon-carbon bonds in the
synthesis of valuable products under mild conditions. The
introduction of new reagents would expand the scope of the
cross-coupling and the Heck-type reactions. Main group
2
3
4
metals such as lead(IV), bismuth, and thallium have been
of limited use as coupling reagents. Recently, Pinhey2
reported the arylation, alkenylation, and alkynylation of
organolead(IV) tricarboxylates with soft carbon nucleophiles.
As an alternative to the use of organic electrophiles, hyper-
valent iodonium compounds were employed in the coupling
with olefins.5 However, to the best of our knowledge,
coupling reactions of organolead compounds as electrophiles
with olefins have not been known. Here, we wish to report
the coupling of olefins with organolead(IV) compounds.
To determine optimum reaction conditions for the coupling
of olefins with organolead triacetates, a series of experiments
were performed on the coupling of 2,3-dihydrofuran(3) with
(p-methoxyphenyl)lead triacetate (1b). After a series of
fruitless experiments, we found that the use of NaOMe (4
equiv) as a base was critical in this type of coupling. By
the use of bases tested, KOAc, Et3N, and K2CO3, the
homocoupled product 4,4′-dimethoxybiphenyl was formed as
major product.6 Among the palladium catalysts Pd(OAc)2,
PdCl2(CH3CN)2, Pd(PPh3)4, Pd(OAc)2, PdCl2(dppf), and
Pd2(dba)3‚CHCl3, Pd2(dba)3‚CHCl3 was the best choice. As
a suitable solvent, the cosolvent CH3CN/MeOH (1:1) was the
most preferable, even though CH3CN/PhH (1:1) was also
effective (eq 1).
a
The isolated yields. b The numbers in parentheses represent
the yields of the homocoupling.
the coupled product trans-stilbene (4a ) in 75% yield (entry
1
, Table 1). Under the same conditions, treatment of 1a with
methyl acrylate (2b) at 60 °C for 4 h gave (E)-methyl
cinnamate (4b) in 71% yield (entry 2). Phenyllead triacetate
(
1a ) underwent facile coupling with diol olefin 2c without
8
any formation of ketone resulting from â-PdH elimination
to give 4c (entry 3). The palladium-catalyzed phenylation
of 2,3-dihydrofuran (3) was accomplished with 1a to give the
thermodynamically less stable 2-substituted 2,5-dihydro-
7
Accordingly, the phenyllead triacetate (1a ) was reacted
with styrene (2a ) at room temperature in the presence of
Pd2(dba)3‚CHCl3 (5 mol %) and NaOMe(4 equiv) to afford
9
furans 5a as a major product (entry 4). When the substi-
tuted phenyllead acetate 1b10 was reacted with the acetonide
(
1) (a) Heck. K. F. Acc. Chem. Res. 1979, 12, 146-151. (b) de Meijere,
A.; Meyer, F. E. Angew. Chem. Int. Ed. Engl. 1994, 33, 2379-2411.
11
2
d under similar conditions, the coupled product 4d was
(
2) (a) Pinhey, J . T. Aust. J . Chem. 1991, 44, 1353-1382. (b) Pinhey, J .
readily obtained in 70% yield (entry 5). The diol cyclic
carbonate 2e12 was also smoothly coupled with (p-methoxy-
phenyl)lead triacetate to afford the substituted cyclic car-
bonate 4e11 without ring opening (entry 6). For the 2,3-
dihydrofuran, the palladium-catalyzed arylation gave the
kinetically favored product 5b in 80% yield (entry 7). This
T. Pure Appl. Chem. 1996, 68, 819-824. (c) Hashimoto, S.; Miyazaki, Y.;
Shinoda, T.; Ikegami, S. J . Chem. Soc., Chem. Commun. 1990, 1100-1102.
(
(
3) Matano, Y.; Suzuki, H. Bull. Chem. Soc. J pn. 1996, 69, 2673-2681.
4) (a) Larock, R. C.; Fellows, C. A. J . Am. Chem. Soc. 1982, 104, 1900-
13
1
1
3
907. (b) Larock, R. C.; Varaprah, S.; Lau, H. H.; Fellows, C. A. Ibid. 1984,
06, 5274-5284. (c) Tayler, E. C.; Mckil- lop, A. Acc. Chem. Res. 1970, 3,
38-346. (d) Larock, R. C.; Yang, H. Synlett 1994, 748-750.
(5) (a) Moriarty, R. M.; Epa, W. R.; Awasthi, A. K. J . Am. Chem. Soc.
1
4
coupling was applied to (2-thienyl)lead triacetate(1c),
1
991, 113, 6315-6317. (b) Kang, S.-K.; Lee, H.-W.; J ang, S.-B.; Kim, T.-H.;
Pyun, S.-J . J . Org. Chem. 1996, 61, 2604-2605.
6) The substituted lead(IV) triacetates undergo homocoupling in the
presence of Pd (dba) ‚CHCl (5 mol %) in CHCl at room temperature for
0 min. See: Kang, S.-K.; Shivkumar, U.; Ahn, C.; Choi, S.-C.; Kim, J .-S.
Synth. Commun. 1997, 27, 1893-1897.
7) Morgan, J .; Pinhey, J . T. J . Chem. Soc., Perkin Trans. 1 1990, 715-
20.
(
2
3
3
3
(8) In the case of allylic alcohols, palladium-catalyzed reaction of organic
halides usually affords â-substituted ketones or aldehydes rather than the
â-substituted allylic alcohols. See: (a) Melpolder, J . B.; Heck, R. F. J . Org.
Chem. 1976, 41, 265-272. (b) Tamara, Y.; Yamada, Y.; Yoshida, Z.-i.
Tetrahedron 1979, 35, 329-340 and references therein.
1
(
7
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Published on Web 07/30/1998