Copper-mediated coupling of zirconacyclopentadienes with dihalo aromatic compounds. Formation of fused aromatic rings

Article abstract of DOI:10.1021/ja960407x

In this paper we report a copper-mediated intermolecular coupling of zirconacyclopentadienes with dihalo aromatic rings. This reaction can provide a novel preparative method of fused aromatic ring compounds. Yields were dependent on the amount of dimethylpropylene(urea) (DMPU). When 1.0 equiv of DMPU was used, the yields were 50-60%. The best yields were obtained when 2.5-3.0 equiv of DMPU was used. The use of HMPA instead of DMPU gave the same result.

Full text of DOI:10.1021/ja960407x

5154
J. Am. Chem. Soc. 1996, 118, 5154-5155
cycloaddition reaction of zirconacyclopentadienes.8 During the
Copper-Mediated Coupling of
course of our study on carbon-carbon bond formation reactions
of zirconacyclopentadienes, we found a novel type of coupling
reaction. In this paper we report a copper-mediated intermo-
lecular coupling of zirconacyclopentadienes with dihalo aromatic
rings. This reaction can provide a novel preparative method
of fused aromatic ring compounds.
Zirconacyclopentadienes with Dihalo Aromatic
Compounds. Formation of Fused Aromatic Rings
Tamotsu Takahashi,*,† Ryuichiro Hara,‡
Yasushi Nishihara,† and Martin Kotora‡
The typical procedure is as follows. To a mixture of
zirconacyclopentadiene 1a which was prepared from Cp2ZrBu2
(Negishi reagent)4a and 2 equiv of 3-hexyne in THF were added
2.1 equiv of copper chloride, 3 equiv of DMPU (N,N′-
(dimethylpropylene)urea) and 1 equiv of diiodobenzene at room
temperature. The mixture was stirred at 50 °C for 2 h.
Naphthalene derivative 2a was formed in 89% yield. Zircona-
cyclopentadiene 1a was completely consumed. After hydrolysis
4,5-diethyl-3,5-octadiene was not obtained. At room temper-
ature, a long reaction time was required.
Catalysis Research Center and
Graduate School of Pharmaceutical Sciences
Hokkaido UniVersity
Kita-ku, Sapporo 060, Japan
Coordination Chemistry Laboratories
Institute for Molecular Science
Myodaiji, Okazaki 444, Japan
ReceiVed February 7, 1996
Coupling reactions between sp2 carbon centers such as
alkenyl-aryl coupling reactions have been very attractive for
organic synthesis since alkenylmetals can be readily prepared
from alkynes.1 Metallacyclopentadienes are also conveniently
prepared from two alkynes and low-valent metal species.2
However, there is no precedent for the intermolecular coupling
of metallacyclopentadienes with dihalo aromatic compounds to
form fused aromatic rings (eq 1), to the best of our knowledge.
Yields were dependent on the amount of DMPU. Without
DMPU, 2a was not formed. When 1.0 equiv of DMPU was
used, the yields were 50-60%. The best yields were obtained
when 2.5-3.0 equiv of DMPU was used. The use of HMPA
instead of DMPU gave the same result.
Recently we have reported copper-catalyzed or -mediated
double allylation reaction7 and cycloaddition reaction8 of
zirconacyclopentadienes. For these reactions the use of DMPU
was not necessary. In this coupling reaction to form fused
aromatic compounds, the effect of addition of DMPU was
remarkable. Addition of CuCl to a THF solution of 1a prepared
in situ led to the gradual formation of insoluble yellow
precipitates. When DMPU was added to the mixture, the yellow
powder was dissolved in THF to form a dark brown solution.
When 1,2-diiodobenzene was added to this solution, 2a was
formed. However, in the absence of 1,2-diiodobenzene, diene
Symmetrical or unsymmetrical zirconacyclopentadienes have
been easily prepared from alkynes or diynes in high yields with
high selectivities.3-5 In order to use these useful zirconacy-
clopentadienes,6 we have developed novel carbon-carbon bond
formation reactions such as double allylation reaction7 and
† Hokkaido University.
‡ Institute for Molecular Science.
(1) Knight, D. W. In ComprehensiVe Organic Synthesis; Trost, B. M.,
Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 3, pp 481-520.
(2) Grotjahn, D. B. In ComprehensiVe Organometallic Chemistry II; Abel,
E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: New York,
1995; Vol. 12, Hegedus, L. S., Ed., pp 741-770 and references therein.
(3) For symmetrical zirconacyclopentadienes, see: (a) Braye, E. H.;
Hubel, W.; Capelier, I. J. Am. Chem. Soc. 1961, 83, 4406-4413. (b)
Sonogashira, K.; Hagihara, N. Bull. Chem. Soc. Jpn. 1966, 39, 1178-1182.
(c) Watt, G. W.; Drummond, F. O., Jr. J. Am. Chem. Soc. 1970, 92, 826-
828. (d)Alt, H.; Rausch, M. D. J. Am. Chem. Soc. 1974, 96, 5936-5937.
(e) Yoshifuji, M.; Gell, K. I.; Schwartz, J. J. Organomet. Chem. 1978, 153,
C15-C18. (f) Hunter, W. E.; Atwood, J. L.; Fachinetti, G.; Floriani, C. J.
Organomet. Chem. 1981, 204, 67-74. (g) Thanedar, S.; Farona, M. F. J.
Organomet. Chem. 1982, 235, 65-68. (h) Skibbe, V.; Erker, G. J.
Organomet. Chem. 1983, 241, 15-26.
(4) For zirconacyclopentadienes prepared from diynes, see: (a) Negishi,
E.; Swanson, D. R.; Cederbaum, F. E.; Takahashi, T. Tetrahedron Lett.
1986, 27, 2829-2832. (b) Nugent, W. A.; Thorn, D. L.; Harlow, R. L. J.
Am. Chem. Soc. 1987, 109, 2788-2796. (c) Negishi, E.; Holms, S. J.; Tour,
J.; Miller, J. A.; Cederbaum, F. .E.; Swanson, D. R.; Takahashi, T. J. Am.
Chem. Soc. 1989, 111, 3336-3346.
derivatives containing metals such as Cu and Zr in the mixture
gradually decomposed to afford undefined compounds. When
iodobenzene was used instead of 1,2-diiodobenzene in the
reaction of 1a, 3-phenyl-4,5-diethyl-3,5-octadiene was obtained
in 75% yield.
The results are shown in Table 1. For various zirconacy-
clopentadienes, the corresponding fused aromatic compounds
were obtained in good to high yields. Zirconacyclopentadiene
1b prepared from 2 equiv of 5-decyne gave a high yield of
1,2,3,4-tetrabutylnaphthalene (2b) (88% yield). Unsymmetrical
zirconacyclopentadiene 1c afforded the corresponding unsym-
metrical 2c in 53% yield. When the starting zirconacyclopen-
tadiene 1d was a mixture of regioisomers, the product 2d was
also a mixture of two regioisomers. Zirconacyclopentadienes
1e and 1f prepared from diynes provided tetrahydroanthracenes
2e and 2f, respectively. The structure of 2e was characterized
by X-ray analysis and is shown in Figure 1. This structure
clearly showed the formation of fused aromatic compound 2e
by the reaction of 1e with 1,2-diiodobenzene. Zirconacyclo-
pentadienes with trimethylsilyl substituents in the R-position
did not react with 1,2-diiodobenzene. When 1,2,4,5-tetraiodo-
benzene was used, a double coupling reaction proceeded to give
anthracene derivative 2h in 62% isolated yield.
(5) For unsymmetrical zirconacyclopentadienes, see: (a) Takahashi, T.;
Swanson, D. R.; Negishi, E. Chem. Lett. 1987, 623-626. (b) Buchwald, S.
L.; Watson, B. T.; Huffman, J. C. J. Am. Chem. Soc. 1987, 109, 2544-
2546. (c) Buchwald, S. L.; Nielsen, R. B. J. Am. Chem. Soc. 1989, 111,
2870-2874. (d)Van Wagenen, B. C.; Livinghouse, T. Tetrahedron Lett.
1989, 30, 3495-3498. (e) Takahashi, T.; Kageyama, M.; Denisov, V.; Hara,
R.; Negishi, E. Tetrahedron Lett. 1993, 34, 687-690. (f) Xi, Z.; Hara, R.;
Takahashi, T. J. Org. Chem. 1995, 60, 4444-4448.
(6) Alkyne insertion of zirocnacyclopentadienes has been reported; see:
(a) Famili, A.; Farona, M. F. Thanedar, S. J. Chem. Soc., Chem. Commun.
1983, 435-436. It was reported that the reaction of Cp2Zr(CO)2 with an
excess of diphenylacetylene gave cyclopentadienone as a minor product.
See: (b) Sikora, D. J. ; Rausch, M. P. J. Organomet. Chem. 1984, 276,
21-37. For main group heterocycle formation from zirconacyclopentadienes,
see: (c) Fagan, P. J.; Nugent, W. A. J. Am. Chem. Soc. 1988, 110, 2310-
2312. (d) Fagan, P. J.; Nugent, W. A.; Calabrese, J. C. J. Am. Chem. Soc.
1994, 116, 1880-1889.
(8) Takahashi, T.; Kotora, M.; Xi, Z. J. Chem. Soc., Chem. Commun.
1995, 361-362.
(9) For transmetalation of other zirconacycles to Cu, see: (a) Kasai, K.;
Kotora, M.; Suzuki, N.; Takahashi, T. J. Chem. Soc., Chem. Commun. 1995,
109-110. (b) Lipshutz, B. H.; Segi, M. Tetrahedron 1995, 51, 4407-4420.
(7) Takahashi, T.; Kotora, M.; Kasai, K.; Suzuki, N. Organometallics
1994, 13, 4183-4185.
S0002-7863(96)00407-6 CCC: $12.00 © 1996 American Chemical Society

Communications to the Editor
J. Am. Chem. Soc., Vol. 118, No. 21, 1996 5155
Table 1. Reactions of Zirconacyclopentadienes with Dihalo or
Tetrahalo Aromatic Compoundsa
Figure 1. Structure of 2e.
gave 2a in 89% yield. Similarly, 2,3-dibromothiophene did not
afford the coupling product on treatment with 1a. However,
2-iodo-3-bromothiophene reacted with 1a to give 2g in 32%
yield. This suggested that a plausible mechanism of this
coupling reaction involves a stepwise coupling. The high
reactivity of iodide is required for the first intermolecular
coupling step. When zirconacyclopentadiene 1a is treated with
CuCl, transmetalation of the diene moiety from zirconium to
copper proceeded to form 3 as usually observed.7-10 1-Bromo-
2-iodobenzene reacts with 3 to give 4. For the second step
which is intramolecular coupling, bromide is reactive enough.
a All reactions were carried out at 50 °C. Reaction time 3 h unless
otherwise noted. b Isolated yields are shown in parentheses. c A mixture
of regioisomers were obtained in a ratio of 5.6:1. The minor isomer
was 1,4-diphenyl-2,3-dibutylnaphthalene. d Reaction time 6 h.
1,2-Dibromobenzene was not reactive in this reaction. Only
4% of 2a was formed at 50 °C even after 12 h. Most of the
1,2-dibromobenzene remained unreacted. However, reaction of
1a with 1-bromo-2-iodobenzene instead of 1,2-dibromobenzene
(10) Transmetalation of alkenyl carbons from zirconium to copper has
been reported. See: (a) Yoshifuji, M.; Loots, M.; Schwartz, J. Tetrahedron
Lett. 1977, 1303-1306. (b) Lipshutz, B. H.; Ellsworth, E. L. J. Am. Chem.
Soc. 1990, 112, 7440-7441. (c) Babiak, K. A.; Behling, J. R.; Dygos, J.
H.; McLanghlin, K. T.; Ng, J. S.; Kalish, V. J.; Kramer, S. W.; Shone, R.
L. J. Am. Chem. Soc. 1990, 112, 7441-7442. (d) Lipshutz, B. H.; Hato, K.
Tetrahedron Lett., 1991, 32, 5647-5650. (e) Lipshutz, B. H.; Fatheree, P.;
Hagan, W.; Stevens, K. L. Tetrahedron Lett. 1992, 33, 1041-1044. (f)
Lipshutz, B. H.; Keil, R. J. Am. Chem. Soc. 1992, 114, 7919-7920. (g)
Lipshutz, B. H.; Wood, M. R. J. Am. Chem. Soc. 1993, 115, 12625-12626.
(h) Takahashi, T.; Kotora, M.; Kasai, K.; Suzuki, N. Tetrahedron Lett. 1994,
35, 5685-5688. (i) Takahashi, T.; Kotora, M.; Fischer, R.; Nishihara, Y.;
Nakajima, K. J. Am. Chem. Soc. 1995, 117, 11039-11040.
Further investigations are now in progress in this area.
Supporting Information Available: Details of the experimental
procedure and analytical data for compounds 2a-2h and X-ray analysis
data of 2e (12 pages). Ordering information is given on any current
masthead page.
JA960407X