LETTER
Reaction of Aryne–Zirconocene Complexes and Enol Ethers
2515
Table 2 Reaction of Organolithium Compounds 14 with Zirconocene Methyl Chloride
Organolithium 14 R1
R2
H
H
H
H
H
H
Enol ether 16 or 18 E+
E
Product 17 or 19
Yield (%)a
14a
14a
14a
14b
14b
14b
14d
14d
14d
14d
14d
H
16
16
18
16
16
18
16
16
16
18
18
H2O
H
17a
17b
19a
17c
17d
19b
17e
17f
71
60
55
64
70
72
88
54
76
82
80
H
Allylchloride, cat. CuCl
Allyl
H
H
H2O
OMe
D2O
D
OMe
Allylchloride, cat. CuCl
Allyl
H
OMe
H2O
–(CH)4–
–(CH)4–
–(CH)4–
–(CH)4–
–(CH)4–
H2O
H
I2
I
Allylchloride, cat. CuCl
H2O
Allyl
H
17g
19c
19d
Allylchloride, cat. CuCl
Allyl
a Yield based on starting 14.
Zirconium-Mediated Couplings of Organolithium Compounds
14 and Butyl Vinyl Ether to give Compounds 15. Typical Proce-
dure.
References
(1) (a) Hart, D. W.; Schwartz, J. J. Am. Chem. Soc. 1974, 96,
8115. (b) Hart, D. W.; Blackburn, T. F.; Schwartz, J. J. Am.
Chem. Soc. 1975, 97, 679. (c) Bertelo, C. A.; Schwartz, J. J.
Am. Chem. Soc. 1976, 98, 262. (d) Schwartz, J.; Labinger, J.
A. Angew. Chem., Int. Ed. Engl. 1976, 15, 333.
The corresponding aryllithium compound 14 (2 mmol) was added
dropwise to a –78 °C stirred solution of zirconocene methyl chlo-
ride (2 mmol) and butyl vinyl ether (3 mmol) in dry THF (10 mL)
in a sealed tube. After 30 min at this temperature, the solution was
allowed to warm to r.t. and then heated to 80 °C for 3 h. The reaction
was cooled to r.t. and the corresponding electrophile was added (ex-
cess of water, deuterium oxide, or 2 mmol of iodine). After 1 h, the
reaction was worked up by addition of H2O (20 mL) or a sat. solu-
tion of Na2S2O3 (20 mL, when iodine was used as electrophile) and
extracted with Et2O (3 × 10 mL). When allyl chloride is used as
electrophile: allyl chloride (3 mmol), and CuCl (5 mol%) were add-
ed and the reaction mixture stirred for 1 h at 25 °C and then heated
at 80 °C for 20 min. After cooling to r.t., the reaction was worked
up by addition of H2O (20 mL) and extracted with Et2O (3 × 10
mL). When iodobenzene is used as electrophile: zinc dichloride
(2.4 mmol), Pd(PPh3)4 (5 mol%), and iodobenzene (3 mmol) were
added and the reaction mixture stirred for 6 h at 25 °C. After cooling
to r.t., the reaction was worked up by addition of H2O (20 mL) and
extracted with Et2O (3 × 10 mL). The combined organic layers were
dried over anhyd Na2S2O3, concentrated and the residue purified by
column chromatography to give compounds 15.
(2) Negishi, E.; Takahashi, T. Acc. Chem. Res. 1994, 27, 124;
and references therein.
(3) See for example: (a) Titanium and Zirconium in Organic
Synthesis; Marek, I., Ed.; Wiley-VCH: Weinheim
(Germany), 2002. (b) New Aspects of Zirconium Containing
Organic Compounds, Topics in Organometallic Chemistry,
Vol 10; Marek, I., Ed.; Springer: Berlin, 2005.
(4) Barluenga, J.; Rodríguez, F.; Álvarez-Rodrigo, L.; Fañanás,
F. J. Chem. Soc. Rev. 2005, 34, 762.
(5) (a) Barluenga, J.; Sanz, R.; Fañanás, F. J. Z. Naturforsch., B:
Chem. Sci. 1995, 50, 312. (b) Takahashi, T.; Kondakov, D.
Y.; Xi, Z.; Suzuki, N. J. Am. Chem. Soc. 1995, 117, 5871.
(c) Barluenga, J.; Rodríguez, F.; Álvarez-Rodrigo, L.;
Fañanás, F. J. Chem.–Eur. J. 2004, 10, 101. (d) For a
related method to access to dienylzirconocene complexes,
see: Chinkov, N.; Majumdar, S.; Marek, I. J. Am. Chem. Soc.
2003, 125, 13258.
(6) (a) Liard, A.; Marek, I. J. Org. Chem. 2000, 65, 7218.
(b) Liard, A.; Kaftanov, J.; Chechik, H.; Farhat, S.;
Morlender-Vais, N.; Averbuj, C.; Marek, I. J. Organomet.
Chem. 2001, 624, 26. (c) Chinkov, N.; Chechik, H.;
Majumdar, S.; Liard, A.; Marek, I. Synthesis 2002, 2473.
(7) Barluenga, J.; Álvarez-Rodrigo, L.; Rodríguez, F.; Fañanás,
F. J. Angew. Chem. Int. Ed. 2004, 43, 3932.
Acknowledgment
Financial support for this work was provided by the Dirección
General de Investigación Científica y Técnica (DGICYT) of Spain
(BQU-2001-3853 and CTQ2004-08077-C02-01/BQU) and Mini-
sterio de Educación y Cultura of Spain (grant to L. A.-R.). F. R.
thanks the funding from the MCYT (Programa Ramón y Cajal).
(8) Barluenga, J.; Rodríguez, F.; Álvarez-Rodrigo, L.; Zapico, J.
M.; Fañanás, F. J. Chem.–Eur. J. 2004, 10, 109.
(9) Buchwald, S. L.; Nielsen, R. B. Chem. Rev. 1988, 88, 1047.
Synlett 2005, No. 16, 2513–2515 © Thieme Stuttgart · New York