COMMUNICATIONS
[
[
8] BSA N,O-bis(trimethylsilyl)acetamide.
9] a) Crystal data for C32 SPd ´ BF : M
, a 14.521(4), b 16.047(5), c 13.971(4) , V
H
43OP
2
4
r
730.92, orthorhombic,
space group P2
3
1
2
1
2
1
3
� 3
� 1
255(2) , Z 4, 1calcd 1.49 gcm , m(CuKa) 6.65 mm . Data were
collected on a Philips PW1100/16 diffractometer with graphite-
monochromated CuKa radiation (l 1.5418 ) at � 1008C. A yellow
crystal of dimensions 0.02 Â 0.30 Â 0.30 mm was used, and a total of
2
3
270 reflections were collected (3 < q < 548); 1931 reflections with I >
s(I) were used for structure determination and refinement. The
structure was solved by direct methods and refined against jF j .
Hydrogen atoms were introduced as fixed contributors. Empirical
absorption corrections, transmission factors: 0.53/1.00. For all compu-
[
9b]
tations the Nonius OpenMoleN package was used. The absolute
structure was determined by refining the Flack x parameter: x
0
.02(2). Final results: R(F) 0.032, Rw(F) 0.045, GOF 1.051,
� 3
maximum residual electron density 0.69 e . Crystallographic data
excluding structure factors) for the structure reported in this paper
(
Scheme 2. Preferential formation of the product with S configuration. The
methyl groups at C11 and C32 are represented by black circles, and the Pd
atom by a gray circle.
have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-101072. Copies of
the data can be obtained free of charge on application to CCDC,
1
2 Union Road, Cambridge CB21EZ, UK (fax: (44)1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk). b) C. K. Fair in MoleN. ªAn
Interactive Intelligent System for Crystal Structure Analysisº. Nonius,
Delft, The Netherlands, 1990.
nated between C1 and C3, which otherwise differ little in their
steric and electronic properties.
Received: March 5, 1998
[
10] A SPARTAN computer graphic programme was used, but in view of
the approximate nature of these calculations, more detailed studies
are in progress.
Revised version: July 23, 1998 [Z11557IE]
German version: Angew. Chem. 1998, 110, 3299 ± 3301
[
11] The involvement of a rotational motion to explain, in part, the
enantioselectivity of catalytic reactions with a P ± N ligand was
Keywords: alkylations ´ asymmetric catalysis ´ chiral ligands
[
3f]
´
homogeneous catalysis ´ palladium
proposed by Brown et al. See also ref. [3d].
[
1] Reviews: a) B. M. Trost, D. L. van Vranken, Chem. Rev. 1996, 96,
395 ± 422; b) T. Hayashi in Catalytic Asymmetric Synthesis, Vol. 1 (Ed.:
I. Ojima), VCH, New York, 1993, pp. 325 ± 365; c) C. G. Frost, J.
Howarth, J. M. J. Williams, Tetrahedron: Asymmetry 1992, 3, 1089 ±
Mechanistic Implications of the Observation of
Kinetic Resolution in a Palladium-Catalyzed
Enantioselective Allylic Alkylation**
1
2
122; d) G. Consiglio, R. M. Waymouth, Chem. Rev. 1989, 89, 257 ±
76.
[
2] However, see a) G. Knühl, P. Sennhenn, G. Helmchen, J. Chem. Soc.
Chem. Commun. 1995, 1845 ± 1846; b) B. M. Trost, A. C. Krueger,
R. C. Bunt, J. Zambrano, J. Am. Chem. Soc. 1996, 118, 6520 ± 6521.
3] Both early and late transition states have been proposed. Early
transition states: a) P. B. Mackenzie, J. Whelan, B. Bosnich, J. Am.
Chem. Soc. 1985, 107, 2046 ± 2054; b) J. Sprinz, M. Kiefer, G.
Helmchen, M. Reggelin, G. Huttner, O. Walter, L. Zsolnai, Tetrahe-
dron Lett. 1994, 35, 1523 ± 1526; c) P. S. Pregosin, R. Salzmann, A.
Togni, Organometallics 1995, 14, 842 ± 847; d) A. Togni, U. Burck-
hardt, V. Gramlich, P. S. Pregosin, R. Salzmann, J. Am. Chem. Soc.
Shailesh Ramdeehul, Peter Dierkes, Rafael Aguado,
Paul C. J. Kamer, Piet W. N. M van Leeuwen, and
John A. Osborn*
[
The mechanism of Pd-catalyzed enantioselective allylic
alkylation involves two steps which are of major importance
in the catalytic cycle.[ First, the allylic substrate, usually in the
1]
1996, 118, 1031 ± 1037; late transition states: e) B. M. Trost, L. Weber,
P. E. Strege, T. J. Fullerton, T. J. Dietsche, J. Am. Chem. Soc. 1978, 100,
[
*] Prof. J.A. Osborn, S. Ramdeehul, Dr. R. Aguado
Laboratoire de Chimie des M e taux de Transition et de Catalyse
Universit e Louis Pasteur
3416 ± 3426; f) J. M. Brown, D. I. Hulmes, P. J. Guiry, Tetrahedron
1994, 50, 4493 ± 4506; g) P. von Matt, G. Lloyd-Jones, A. B. E. Minidis,
A. Pfaltz, L. Macko, M. Neuburger, M. Zehnder, H. Rüegger, P. S.
Pregosin, Helv. Chim. Acta 1995, 78, 265 ± 284; h) H. Steinhagen, M.
Reggelin, G. Helmchen, Angew. Chem. 1997, 109, 2199 ± 2202; Angew.
Chem. Int. Ed. Engl. 1997, 36, 2108 ± 2110.
Institut Le Bel, UMR7513CNRS
4
rue Blaise Pascal, F-67070 Strasbourg Cedex (France)
Fax: (33)388-416-171
E-mail: osborn@chimie.u-strasbg.fr
[
4] a) M. Kranenburg, J. G. P. Delis, P. C. J. Kamer, P. W. N. M. van Leeu-
wen, K. Vrieze, N. Veldman, A. L. Spek, K. Goubitz, J. Fraanje, J.
Chem. Soc. Dalton Trans. 1997, 1839 ± 1849; b) M. Kranenburg,
Y. E. M. van der Burgt, P. C. J. Kamer, P. W. N. M. van Leeuwen,
Organometallics 1995, 14, 3081 ± 3089; c) M. Kranenburg, P. C. J.
Kamer, P. W. N. M. van Leeuwen, Eur. J. Inorg. Chem. 1998, 25 ± 27.
Prof. P. W. N. M van Leeuwen, Dr. P. Dierkes, Dr. P. C. J. Kamer
Universiteit van Amsterdam
Institute for Molecular Chemistry
vanꢁt Hoff Research Institute
Nieuwe Achtergracht 166
NL-1018 WV Amsterdam (The Netherlands)
[
[
5] M. J. Burk, M. F. Gross, Tetrahedron Lett. 1994, 35, 9363 ± 9366.
6] A ligand derived from the xanthene backbone with chirality at
phosphorus was recently reported: Y. Hamada, F. Matsuura, M. Oku,
K. Hatano, T. Shioiri, Tetrahedron Lett. 1997, 38, 8961 ± 8964.
[
**] This work was supported by the Minist eÁ re de la Recherche et de
l'Enseignement Sup e rieur (Ph.D. fellowship for S.R.), the Deutsche
Forschungsgemeinschaft (Postdoctoral Fellowship for P.D.), the Euro-
pean Commission (Marie Curie Research Fellowship, ERBFM-
BICT972198, for R.A.), the European Union (MMCOS network),
and the CNRS (UMR 7513).
[
7] The configurations of the products were assigned by comparison of
their optical rotations with literature data: a) P. Sennhenn, B. Gabler,
G. Helmchen, Tetrahedron Lett. 1994, 35, 8595 ± 8598; b) B. M. Trost,
A. C. Krueger, R. C. Bunt, J. Zambrano, J. Am. Chem. Soc. 1996, 118,
Supporting information for this article is available on the WWW
under http://www/wiley-vch.de/home/angewandte/ or from the
author.
6520 ± 6521; c) P. von Matt, A. Pfaltz, Angew. Chem. 1993, 105, 614 ±
16; Angew. Chem. Int. Ed. Engl. 1993, 32, 566 ± 568.
6
3
118
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
1433-7851/98/3722-3118 $ 17.50+.50/0
Angew. Chem. Int. Ed. 1998, 37, No. 22