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J. Am. Chem. Soc. 2000, 122, 3228-3229
Scheme 1
Metallo-Esterification of Alkynes: Reaction of
Alkynes with Cp2ZrEt2 and Chloroformate
Tamotsu Takahashi,* Chanjuan Xi, Yasuyuki Ura, and
Kiyohiko Nakajima†
Catalysis Research Center and
Graduate School of Pharmaceutical Sciences
Hokkaido UniVersity
CREST, Science and Technology Corporation (JST)
Sapporo 060-0811, Japan
Department of Chemistry
Aichi UniVersity of Education
Igaya, Kariya 448-8542, Japan
ReceiVed December 6, 1999
Carbometalation of alkynes is a very attractive reaction for the
preparation of stereodefined substituted olefins.1 Among olefins,
R,â-unsaturated ester is one of the most useful compounds in
organic synthesis. Metallo-esterification of alkynes is a simple
and direct preparative method of such stereodefined substituted
metallo-propenoates 1 (eq 1), which can be converted into
sp2 carbons appeared at 179.56, 151.04, and 137.04 ppm,
assignable to Zr-C(Ph)d, -C(dO)OEt, and -C(Ph)dC(Ph)-C,
respectively.
Hydrolysis of 2a with 3 N HCl gave ethyl-(E)-2,3-diphenyl-
propenoate 3a in 93% yield. Deuteriolysis and iodinolysis instead
of hydrolysis of 2a afforded the monodeuterated compound 4a
in 95% yield with 91% deuterium incorporation and monoiodi-
nated product 5a in 90% yield, respectively.
To confirm the structure of the zircono-esterification product
2, white crystals of 2b (R1 ) R2 ) Ph, R ) Me) suitable for
X-ray analysis were obtained at -40 °C in THF. The structure
of 2b is shown in Figure 1. It clearly shows the formation of
zircono-esterification product of diphenylacetylene and also
reveals the coordination of the carbonyl group to the zirconium
metal center.
variously functionalized R,â-unsaturated esters. However, there
is no procedure for metallo-esterification of alkynes, although
chloro-esterification2 and hydro-esterification of alkynes3,4 and
acyl-metalation5-7 have been reported.
In this paper, we report metallo-esterification of alkynes based
on the reaction of alkynes with Cp2ZrEt2 and chloroformate (eq
2). Moreover, the resulting metallo-esterification product 2 further
The zircono-esterification products of alkynes could be con-
verted into functionalized stereodefined R,â-unsaturated esters by
coupling with various electrophiles such as acyl chlorides,10
iodobenzene,11 alkynyl iodide,12 NCS and NBS13 in the presence
of a catalytic amount of Pd(PPh3)4 and/or CuCl.14 The various
(5) For the reaction of alkyne with a Ni complex and CO2, see: (a) Hoberg,
H.; Schaefer, D.; Burkhart, G.; Kru¨ger, C.; Romao, M. J. J. Organomet. Chem.
1984, 266, 203 and references therein. (b) Hoberg, H.; Apotecher, B. J.
Organomet. Chem. 1984, 270, C15.
(6) For acyl-metalation using a Mn complex and CO, see: (a) DeShong,
P.; Sidler, D. R.; Rybczynski, P. J.; Slough, G. A.; Rheingold, A. L. J. Am.
Chem. Soc. 1988, 110, 1575 and references therein. (b) DeShong, P.; Sidler,
D. R. J. Org. Chem. 1988, 53, 4892.
(7) For the reaction of alkynes with a Ta complex and RNCO, see: Takai,
K.; Kataoka, Y.; Yoshizumi, K.; Oguchi, Y.; Utimoto, K. Chem. Lett. 1991,
1479-1482.
(8) (a) Takahashi, T.; Seki, T.; Nitto, Y.; Saburi, M.; Rousset, C. J.; Negishi,
E. J. Am. Chem. Soc., 1991, 113, 6266-6268. (b) Takahashi, T.; Suzuki, N.;
Kageyama, M.; Nitto, Y.; Saburi, M.; Negishi, E. Chem. Lett. 1991, 1579-
1582.
reacted with various electrophiles to form highly substituted
propenoates (Scheme 1).
A zircono-esterification product of diphenylacetylene 2a was
formed in 95% NMR yield. The 1H NMR spectrum of 2a showed
a singlet signal at 5.97 ppm assigned to Cp protons. In its 13C
NMR spectrum, Cp carbons appeared at 111.92 ppm and three
† Aichi University of Education.
(1) Knochel, P. In ComprehensiVe Organic synthesis; Trost, B. M., Fleming,
I., Semmelhack, M. F., Eds.; Pergamon Press: New York, 1991; Vol. 4,
Chapter 4, pp 865-911.
(2) For chloro-esterification of alkynes by Rh complexes, see: (a) Hua,
R.; Shimada, S.; Tanaka, M. J. Am. Chem. Soc. 1998, 120, 12365-12366.
For the Pd/Cu system, see: (b) Li, J.; Jiang, H.; Feng, A.; Jia, L. J. J. Org.
Chem. 1999, 64, 5984-5987.
(9) (a) Takahashi, T.; Kageyama, M.; Denisov, V.; Hara, R.; Negishi, E.
Tetrahedron Lett. 1993, 34, 687-690. (b) Takahashi, T.; Xi, Z.; Rousset, C.
J.; Suzuki, N. Chem. Lett. 1993, 1001-1004. (c) Xi, Z.; Hara, R.; Takahashi,
T. J. Org. Chem. 1995, 60, 4444-4448.
(3) For hydro-esterification of alkynes, see: (a) Hiyama, T.; Wakasa, N.;
Ueda, T.; Kusumoto, T. Bull. Chem. Soc. Jpn. 1990, 63, 640-642. (b)
Scarivanti, A.; Chinellato, R.; Matteoli, U. J. Mol. Catal. 1993, 84, L141-
144. (c) Kushino, Y.; Itoh, K.; Miura, M.; Nomura, M. J. Mol. Catal. 1994,
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Chem. 1995, 503, 21. (e) Xu, W.; Alper, H. Macromolecules 1996, 29, 6695-
6699. (f) Scrivanti, A.; Beghetto, V.; Campagna, E.; Zanato, M.; Matteoli, U.
Organometallics 1998, 17, 630-635.
(10) (a) Takahashi, T.; Kotora, M.; Xi, Z. J. Chem. Soc., Chem. Commun.
1995, 1503-1504. (b) Takahashi, T.; Xi, Z.; Kotora, M.; Xi, C.; Nakajima,
K. Tetrahedron Lett. 1996, 37, 7521-7524.
(11) (a) Takahashi, T.; Hara, R.; Nishihara, Y.; Kotora, M. J. Am. Chem.
Soc. 1996, 118, 5154-5155. (b) Hara, R.; Nishihara, Y.; Landre, P. D.;
Takahashi, T. Tetrahedron Lett. 1997, 38, 447-450.
(12) Hara, R.; Liu, Y.; Sun, W.-H.; Takahashi, T. Tetrahedron Lett. 1997,
38, 4103-4106.
(4) (a) Alper, H.; Saldana-Maldonado, M.; Lin, I. J. B. J. Mol. Catal. 1988,
49, L27-30. (b) El Ali, B.; Alper, H. J. Mol. Catal. 1991, 67, 29-33. (c)
Zargarian, D.; Alper, H. Organometallics 1993, 12, 712-714. (d) El Ali, B.;
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(13) Effect of CuCl for iodination, see: Xi, C.; Huo, S.; Mahmaoud, A.;
Hara, R.; Takahashi, T. Tetrahedron Lett. 1997, 38, 4099-4102.
(14) A review for the C-C bond formation via transmetalation of
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10.1021/ja994234y CCC: $19.00 © 2000 American Chemical Society
Published on Web 03/15/2000