H. Lam et al. / Tetrahedron Letters 43 (2002) 5875–5877
5877
Table 1. Asymmetric palladium-catalysed allylic substitution of 1,3-diphenyl-2-propenyl acetate by dimethyl malonatea
Entry
Ligand
T (°C)
Time (h)
% Conv.
% ee (R/S)
1
2
3
4
5
6
1
1
2
2
3
9
25
0
25
0
25
25
2
24
24
24
2
100
100
100
100
100
100
74 (S)
80 (S)
64 (S)
82 (S)
18.5 (R)
5 (R)
20
a All reactions were duplicated to within 1%. Reaction times are unoptimised. % ee determined by chiral HPLC (Chiralpak AD column).
Organometallics 2002, in press, manuscript number
OM0201314.
8. Qadir, M.; Mo¨chel, T.; Hii, K. K. Tetrahedron 2000, 56,
7975–7979.
9. Parisel, S. L.; Moorcorft, N. D.; Aldous D. J.; Hii K. K.,
unpublished results.
Figure 3.
10. Ariffin, A.; Blake, A. J.; Ebden, M. R.; Li, W.-S.; Simpkins,
N. S.; Fox, D. N. A. J. Chem. Soc., Perkin Trans. 1 1999,
2439–2447.
11. Couturier, M.; Tucker, J. L.; Andresen, B. M.; Dube, E.;
Brenek, S. J.; Negri, J. T. Tetrahedron Lett. 2001, 42,
2285–2288.
Further development of these ligands, as well as optimi-
sation of the associated catalytic chemistry, will be
reported in due course.
Supplementary material
12. Deprotection of aminophosphine borane: A suspension of
Raney nickel (10 mg) in dry methanol (10 mL) was added
to a mixture of aminodiphosphine borane 8 (160 mg, 0.31
mmol) in Et2NH (5 mL). After heating at 55°C overnight,
the solution was filtered through a pad of Celite. The
filtrate was evaporated in vacuo to afford a residue, which
was subjected to flash chromatography (basic alumina).
The aminodiphosphine 1 was isolated as its HCl salt by
adding 1 M HCl solution in ether.
13. Under Ar, a solution of diphenylphosphino acetic acid (688
mg, 2.84 mmol) in dry CH2Cl2 (5 mL) was added slowly
to a solution of DCC (643 mg, 3.12 mmol) and DMAP (694
mmol, 5.68 mmol) in CH2Cl2 (10 mL) at 0°C. After stirring
for 1 h, a suspension of the aminophosphine 9 (860 mg,
2.84 mmol) in CH2Cl2 (10 mL) was added slowly. The
reaction mixture was left to warm to room temperature.
After stirring overnight, degassed water (10 mL) was added
and the suspension was left to stir for another hour. The
precipitated urea was removed by filtration through a pad
of Celite, before the solvents were removed in vacuo. The
oily residue was then purified by flash chromatography to
afford the amidophosphine 2 as a viscous colourless oil
(800 mg, 57%).
Crystallographic data (excluding structure factors) for
the structures in this paper have been deposited with
the Cambridge Crystallographic Data Centre as supple-
mentary publication number CCDC 182801. Copies of
the data can be obtained, free of charge, on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
[fax: +44 (0) 1223-336033 or e-mail: deposit@ccdc.
cam.ac.uk].
Acknowledgements
We are grateful to Aventis Pharmaceuticals, K. C.
Wong Foundation, British FCO, King’s College Lon-
don and The Nuffield Foundation for support of stu-
dentships (H.L., X.C.) and equipment. Palladium salts
are provided generously by Johnson Matthey plc
through a loan agreement.
References
14. Under a N2 atmosphere at ambient temperature, a mixture
of aminophosphine 9 (400 mg, 1.3 mmol), finely ground
K2CO3 (2.0 g, 19 mmol) and 2-N,N-diethylaminoethyl
chloride·HCl (200 mg, 1.2 mmol) were stirred in CH3CN
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(5 mg, 0.30 mmol). The reaction mixture was stirred for
a further 4 h, before it was filtered. The filtrate was
evaporated and purified by column chromatography to
afford ligand 3 as a colourless oil (300 mg, 70%).
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