ORGANIC
LETTERS
2000
Vol. 2, No. 18
2885-2888
Synthesis of New Bicyclic P−N Ligands
and Their Application in Asymmetric
Pd-Catalyzed π-Allyl Alkylation and
Heck Reaction
,†
Scott R. Gilbertson,* Daniel G. Genov,†,§ and Arnold L. Rheingold‡
Department of Chemistry, Washington UniVersity, One Brookings DriVe,
Campus Box 1034, St. Louis, Missouri 63170-4899, and Department of Chemistry and
Biochemistry, UniVersity of Delaware, Newark, Delaware 19716
Received July 11, 2000
ABSTRACT
The synthesis of phosphine oxazoline ligands based on P-chiral 1-phosphanorbornadienes is reported. The use of these ligands in palladium
catalyzed asymmetric allylation and Heck reaction is described.
Optically active C2-symmetric bisphosphines and nonsym-
metric phosphine-oxazoline ligands have been used as chiral
ligands in a wide range of metal-catalyzed asymmetric
reactions.1-8 Many of the known phosphine ligands carry
the chiral information that is ultimately transferred to a
reaction product on their carbon skeleton. Considerably less
attention has been paid to ligands with chiral phosphorus
donors due to the synthetic difficulties associated with such
compounds and their configurational instability particularly
at high temperatures.9-12
In the past few years, practical routes to P-chiral ligands
have been developed, and some of these ligands have been
successfully used in asymmetric hydrogenations.13-15 Mathey
et al. have developed the synthesis of monodentate P-chiral
1-phosphanorbornadienes from phospholes and alkynes.16-20
(8) Ojima, I. Catalytic Asymmetric Synthesis; VCH Publishers: Wein-
heim, 1993.
(9) Pietrusiewicz, K. M.; Zablocka, M. Chem. ReV. 1994, 94, 1375-
1411.
(10) Imamoto, T. In Handbook of Organophosphorus Chemistry; Engel,
R., Ed.; Dekker: New York, 1992.
(11) Kagan, H. B.; Sasaki, M. In Chemistry of Organophosphorus
Compounds; Hartley, F. R., Ed.; Wiley: Chichester, 1990; Vol. 1.
(12) Valentine, D. J. Asymmetric Synthesis; Academic: Orlando, 1984;
Vol. 4.
† Department of Chemistry, Washington University, St. Louis, MO
63130.
‡ Department of Chemistry and Biochemistry, University of Delaware,
Newark, DE 19716.
§ Current address: Catalytica Pharmaceuticals, 430 Ferguson Drive,
Mountain View, CA 94043.
(13) Muci, A. R.; Campos, K. R.; Evans, D. A. J. Am. Chem. Soc. 1995,
117, 9075-9076.
(1) Sawamura, M.; Ito, Y. Chem. ReV. 1992, 92, 857-871.
(2) Burk, M. J.; Feaster, J. E.; Nugent, W. A.; Harlow, R. L. J. Am.
Chem. Soc. 1993, 115, 10125-10138.
(14) Imamoto, T.; Watanabe, J.; Wada, J.; Masuda, H.; Yamada, H.;
Tsuruta, H.; Matsukawa, S.; Yamaguchi, K. J. Am. Chem. Soc. 1998, 120,
1635-1636.
(3) Trost, B. M.; Van Vranken, D. L.; Bingel, C. J. Am. Chem. Soc.
1992, 114, 9327-9343.
(15) Wolfe, B.; Livinghouse, T. J. Am. Chem. Soc. 1998, 120, 5116-
5117.
(4) Pfaltz, A. Acta Chem. Scand. 1996, 50, 189-194.
(5) Kudis, S.; Helmchen, G. Angew. Chem., Int. Ed. Engl. 1998, 37,
3047-3050.
(16) Mathey, F.; Mercier, F.; Charrier, C.; Fischer, J.; Mitschler, A. J.
Am. Chem. Soc. 1981, 103, 4595-4597.
(17) Charrier, C.; Bonnard, H.; de Lauzon, G.; Mathey, F. J. Am. Chem.
Soc. 1983, 105, 6871-6877.
(6) Dawson, G. J.; Frost, G.; Williams, J. M. J. Tetrahedron Lett. 1993,
34, 3149-3150.
(18) Breque, A.; Alcaraz, J.-M.; Ricard, L.; Mathey, F. New J. Chem.
1989, 13, 369-374.
(7) Noyori, R. Asymmetric Catalysis in Organic Synthesis; Wiley &
Sons: New York, 1994.
(19) Mathey, F. Chem. ReV. 1988, 88, 429-453.
10.1021/ol006323h CCC: $19.00 © 2000 American Chemical Society
Published on Web 08/12/2000