ˆ
C. Girard, J.-P. Genet, M. Bulliard
FULL PAPER
[10]
´
ˆ
Babiano, P. Cintas, J. L. Jimenez, J. C. Palacios, Tetrahedron:
Asymmetry 1997, 8, 2997Ϫ3017.
J. P. Genet, V. Ratovelomanana-Vidal, M. C. Can˜o de Andrade,
X. Pfister, P. Guerreiro, J. Y. Lenoir, Tetrahedron Lett. 1995,
36, 4801Ϫ4804.
[3] [3a]
E. J. Corey, M. C. Noe, J. Am. Chem. Soc. 1993, 115,
[3b]
[11]
[12]
´
12579Ϫ12580. Ϫ
M. Kitamura, S. Suga, M. Niwa, R.
X. Pfister, Ph. D. Thesis, Universite Pierre et Marie Curie, 1995.
[3c]
Noyori, J. Am. Chem. Soc. 1995, 117, 4832Ϫ4842. Ϫ
S. Y.
During the in situ preparation of the catalyst using 100% ee
BINAP as diphosphane, the 31P-NMR of the different phases
were recorded.[11] Analysis of the global mixture after the acidic
treatment showed the presence of two species identified as the
(µ2-Br)3(µ3-Br)2 3 trimeric complex (s, δ ϭ 42) and the (µ2-Br)3
4 dimer (2AB, δ ϭ 30, J ϭ 40 Hz and δ ϭ 45, J ϭ 43 Hz).
While the supernatant solution contained complex 3 (s, δ ϭ 42)
the isolated precipitate consisted exclusively of 4 (2AB, δ ϭ 30,
J ϭ 40 Hz and δ ϭ 45, J ϭ 43 Hz). Evaporation of the total
mixture (solution and precipitate) led to a solid which existed
only as a dimeric form (4, 2AB, δ ϭ 30, J 40 Hz and δ ϭ 45,
J ϭ 43 Hz).
Zhang, C. Girard, H. B. Kagan, Tetrahedron: Asymmetry 1995,
6, 2637Ϫ2640.
[4] [4a]
J. W. Faller, J. Parr, J. Am. Chem. Soc. 1993, 115, 804Ϫ805.
[4b]
Ϫ
J. W. Faller, M. Tokunaga, Tetrahedron Lett. 1993, 34,
7359Ϫ7362. [4c] J. W. Faller, D. W. I. Sams, X. Liu, J. Am. Chem.
[4d]
Soc. 1996, 118, 1217Ϫ1218.
R. Sablong, J. A. Osborn, J. W.
[4e]
Faller, J. Organomet. Chem. 1997, 527, 65Ϫ70.
S. Matsukawa, Nature 1997, 385, 613Ϫ615.
K. Mikami,
[5] [5a]
C. Bolm, F. Bienewald, A. Seger, Angew. Chem. 1996,108,
1767Ϫ1769; Angew. Chem. Int. Ed. Engl. 1996, 35, 1657Ϫ1659.
Ϫ
[5b]
T. Shibata, T. Hayase, J. Imamoto, K. Soai, Tetrahedron:
[13]
Asymmetry 1997, 8, 1717Ϫ1719. and references quoted therein.
[6a] For an example of NLE in hydrogenation with a chiral rho-
dium complex, see: J. W. Faller, M. R. Mazzieri, J. T. Nguyen,
In this study, other qualitative observations of importance were
recorded. During in situ preparation of the ruthenium catalyst,
the solutions produced a precipitate after a few minutes, which
was identified as the pre-catalyst itself (vide supra). Further-
more, the solutions prepared from low ee diphosphanes pro-
duced more solids than the enantiomerically-enriched ones.
Since the formation of a larger amount of heterochiral dimer is
expected at lower ee of phosphane, the formation of a larger
amount of precipitated solid can be associated with this species,
which can be more stable and may be less soluble than its
homochiral counterpart. After evaporation of the volatiles from
the catalytic preparation, the hydrogenation was conducted in
ethyl alcohol in which, once again, the catalysts prepared from
less enantiomerically pure diphosphanes are less soluble than
those of higher ee. This indicates that the possible lower solu-
bility, as well as the greater stability of heterodimer towards
hydrogenation, can both contribute to the (ϩ)-NLE observed
here. The lower conversion at low ee of diphosphane can then
be explained by the formation of larger amounts of the less
reactive heterochiral dimer. The quantity of the homochiral
species is then lower at low ee, thus resulting in a decreased
conversion rate during the hydrogenation process when using
nonenantiomerically-pure phosphane. As an example, hydro-
genations using 100% ee BINAP are usually complete within 3
hours at 60°C.[10]
[6]
J. Parr, M. Tokunaga, Pure
& Appl. Chem. 1994, 66,
[6b]
1463Ϫ1469. Ϫ
For an example of a chiral poisoning and
catalyst activation on a ruthenium complex, see: T. Ohkuma,
H. Doucet, T. Pham, K. Mikami, T. Korenaga, M. Terada, R.
[6c]
Noyori, J. Am. Chem. Soc. 1998, 120, 1086Ϫ1087. Ϫ
Chiral
poisoning in ruthenium-catalysed hydrogenation using proatro-
pisomeric diphosphane has been recently published, see: K. Mi-
kami, T. Korenaga, M. Terada, T. Ohkuma, T. Pham, R.
Noyori, Angew. Chem. 1999, 111, 517Ϫ519; Angew. Chem. Int.
Ed. 1999, 38, 495Ϫ497.
[7] [7a]
B. R. James, A. Pacheco, S. J. Rettig, I. S. Thorburn, R. G.
[7b]
Ball, J. A. Ibers, J. Mol. Cat. 1987, 41, 147Ϫ161. Ϫ
James, S. J. Rettig, I. S. Thorburn, A. M. Joshi, Inorg. Chim.
B. R.
[7c]
Acta 1992, 198, 283. Ϫ
Soc., Chem. Commun. 1991, 1675Ϫ1677. Ϫ
Costella, A. Del Zotto, P. Rigo, G. Consiglio, Gaz. Chim. Ital.
1993, 123, 155Ϫ164. Ϫ
Ohkuma, R. Noyori, Org. Synth. 1993, 71, 1Ϫ13.
A. Mezzetti, G. Consiglio, J. Chem.
[7d]
A. Mezzetti, L.
[7e]
M. Kitamura, M. Tokunaga, T.
[8] [8a]
ˆ
J. P. Genet, C. Pinel, V. Ratovelomanana-Vidal, S. Mallart,
X. Pfister, M. C. Can˜o de Andrade, J. A. Laffitte, Tetrahedron:
[8b]
ˆ
J. P. Genet, C. Pinel, V.
Asymmetry 1994, 5, 665Ϫ674. Ϫ
Ratovelomanana-Vidal, S. Mallart, X. Pfister, L. Bischoff, M.
C. Can˜o de Andrade, S. Darses, C. Galopin, J. A. Laffitte,
Tetrahedron: Asymmetry 1994, 5, 675Ϫ690.
[14] [14a] T. Ohta, H. Takaya, R. Noyori, Tetrahedron Lett. 1990, 31,
7189Ϫ7192. Ϫ [14b] M. T. Ashby, J. Halpern, J. Am. Chem. Soc.
1991, 113, 589Ϫ594.
[9] [9a]
[9b]
ˆ
ˆ
J. P. Genet
J. P. Genet, Acros Org. Acta 1995, 1, 4Ϫ9. Ϫ
[15]
in ACS Symposium Series 641: Reductions in Organic Synthesis.
Recent Advances and Practical Applications (Ed.: A. F. Abdel-
Since some decomposition of ethyl acetoacetate (1) occurred
under the GC analysis conditions, the conversions are only indi-
cated here to demonstrate the progression of the hydrogenation.
Received March 1, 1999
Magid), American Chemical Society, Washington, DC, 1996,
[9c]
ˆ
J. P. Genet, V. Ratovelomanana-Vidal, J. Or-
chapter 2. Ϫ
ganomet. Chem. 1998, 576, 163Ϫ171.
[O99133]
2942
Eur. J. Org. Chem. 1999, 2937Ϫ2942