J. Am. Chem. Soc. 2001, 123, 3167-3168
3167
Unprecedented Highly cis-Diastereoselective Olefin
Cyclopropanation Using Copper Homoscorpionate
Catalysts
ratio, and the porphyrin osmium Os(TPP) (TPP ) tetraphenylpor-
5
phyrin) moved that ratio to 1:13 (cis:trans). On the other hand,
1
few catalysts favor the formation of the cis isomer, the maximum
diastereoselectivity corresponding to Hossain’s iron-based catalyst,
+
6
†
†
2
[Cp(CO) Fe(THF)] , (84:16 cis:trans ratio, 40% yield). The use
M. Mar D ´ı az-Requejo, Tom a´ s R. Belderra ´ı n,
‡
,†
of copper-catalysts have not provided better results: the highest
cis selectivity has been reported by Brunner and co-workers using
a chiral, camphor-derived tetrakispyrazolylborate copper (I)
Swiatoslaw Trofimenko, and Pedro J. P e´ rez*
Departamento de Qu ´ı mica y Ciencia de Materiales
7
UniVersidad de HuelVa
Carretera de Palos de la Frontera s/n
complex, (74:26, cis:trans). The situation with other olefins is
quite similar, and only high trans diastereoselectivities have been
induced by means of very bulky diazoacetates. The menthyl or
the BHT derivatives have provided a noticeable amount of the
2
1819-HuelVa, Spain
Department of Chemistry and Biochemistry
8
UniVersity of Delaware, Newark, Delaware 19716
trans isomer of the corresponding cyclopropanes for 1-alkenes.
More interesting is the cyclopropanation of 2,5-dimethyl-2,4-
hexadiene to give the chrysanthemate ester (eq 2), due to its use
ReceiVed January 23, 2001
Among the metal-based catalysts examined for the intermo-
lecular olefin cyclopropanation reaction, those of rhodium and
1,2
copper have been preferentially employed in the past decade.
Rhodium catalysts are usually derived from Rh (OAc) , and
2
4
complexes containing chiral ligands such as carboxylates or
carboxamidates have induced high enantioselection in this
3
transformation. Porphyrin-rhodium complexes have also shown
1,3
remarkable catalytic activity and asymmetric induction. Copper-
(I) complexes with chiral salicylaldimines, bis(oxazolines), semi-
corrines, and bipyridines have shown similar effect, and high ee’s
have been reported.1 In contrast to these results, there is still
one elusive goal: the diastereocontrol of the reaction. The
influence of the structure (catalyst, olefin) in diastereoselectivity
is not high, a fact that has been rationalized by assuming that the
high reactivity of the metal-carbene complex results in an early
transition state (A) in which the olefin is still a significant distance
-3
in pesticide industry. Previous reports on this reaction gave
preferentially trans diastereoselectivity when the aforementioned
9
bulky diazoacetates where employed. Masamune reported 16:
84 cis:trans formation with a copper-based catalyst and menthyl
diazoacetate. Doyle later provided a 6:94 cis:trans ratio when
using rhodium acetate and BDA as the carbene source. To our
knowledge, a catalyst that generates a diastereomeric excess on
the cis isomer with EDA as the carbene source and 1-alkenes or
from the metal center. Because of this, steric influences are not
important in the induction of diastereomeric excesses (de), unless
very bulky reactants (diazoacetate and olefin) are employed. The
cyclopropanation of styrene with ethyl diazoacetate (EDA) has
been studied as a model for this reaction (eq 1). Most catalysts
2
,5-dimethyl-2,4-hexadiene is yet unknown.
We have recently reported10 the use of bispyrazolylborate-
copper complexes as catalysts for the olefin cyclopropanation
reaction. An earlier report showed11 that the complex Tp*Cu (1;
Tp* ) hydrotris(3,5-dimethylpyrazolyl)borate) catalyzed the
conversion of olefins into the corresponding cyclopropanes, with
a 55:45 cis:trans selectivity. In this contribution we present the
results of the olefin cyclopropanation reaction with a series of in
X
situ generated copper(I) complexes of general formula Tp Cu,
in which the groups attached to the pyrazolyl rings have been
varied to probe steric effects on the catalytic reaction.
The catalyst precursors were prepared in situ upon reacting
CuI with the thalium (or potassium) salt of the corresponding
(
4) Nishiyama, H.; Itoh, Y.; Matsumoto, H.; Park, S.-B.; Itoh, K. J. Am.
lead to cis:trans ratios in the range 50:50 to 25:75.1-3 Only a
Chem. Soc. 1994, 116, 2223
(
5) Smith, D. A.; Reynolds, D. N.; Woo, L. K. J. Am. Chem. Soc. 1993,
few examples are known that have provided high trans diaste-
1
15, 2511
4
reoselectivities. The catalyst RuCl
2
(pybox) gave a 9:91 cis:trans
(6) Seit, W. J.; Saha, A. K.; Hossain, M. M. Organometallics 1993, 12,
604.
(7) Brunner, H.; Singh, U. P.; Boeck, T.; Altmann, S.; Scheck, T.;
2
*
Author correspondence. E-mail: perez@dqcm.uhu.es.
†
Universidad de Huelva.
University of Delaware.
Wrackmeyer, B. J. Organomet. Chem. 1993, 443, C16-C18.
(8) (a) Doyle, M. P.; Bagheri, V.; Wandless, T. J.; Harn, N. K.; Brinker,
D. A.; Eagle, C. T.; Loh, K.-L. J. Am. Chem. Soc. 1990, 112, 1906. (b)
Lowenthal, R. E.; Abiko, A.; Masamune, S. Tetrahedron Lett. 1990, 31, 6008.
(c) Aratani, T. Pure Appl. Chem. 1985, 57, 1839.
(9) Lowenthal, R. E.; Masamune, S. Tetrahedron Lett. 1991, 32, 7373.
(10) D ´ı az-Requejo, M. M.; Nicasio, M. C.; P e´ rez, P. J. Organometallics
1998, 17, 3051.
‡
(1) Doyle, M. P.; McKervey, M. A.; Ye, T. Modern Catalytic Methods for
Organic Synthesis with Diazo Compounds; John Wiley & Sons: New York
998.
2) Doyle, M. P. In ComprehensiVe Organometallic Chemistry II; Abel,
E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U. K.,
995; Vol. 12, p 387.
1
(
1
(
3) (a) Doyle, M. P.; Protopopova, M. N. Tetrahedron 1998, 54, 7919. (b)
(11) (a) P e´ rez, P. J.; Brookhart, M.; Templeton, J. L. Organometallics 1993,
12, 261. (b) Diaz-Requejo, M. M.; P e´ rez, P. J.; Brookhart, M.; Templeton, J.
L. Organometallics 1997, 16, 4399.
Pfaltz, A., Yamamoto, H., Jacobsen, E. N., Eds.; ComprehensiVe Asymmetric
Catalysis; Springer-Verlag 1999; Chapter 16.
1
0.1021/ja0155736 CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/09/2001