Erwan Le Roux et al.
COMMUNICATIONS
À1
2
50 h ) and ees up to >99% with conversions up to General Procedure for Asymmetric Hydrogenation
>
99%). To the best of our knowledge, these activities
À3
In a glove-box, a solution of 6.410 mmol of catalyst,
3
and enantioselectivities are the best ones reported so
far for the iridium-catalyzed hydrogenation of ke-
tones. Future work will focus on investigating the re-
À2
.210 mmol of additives (5 equivs.) and 3.2 mmol of sub-
strate (500 equivs.) in 2 mL of the desired solvent was trans-
ferred into a 5-mL glass ampoule which was then placed
action mechanism and on expanding the substrate into a stainless steel autoclave. The reaction vessel was pres-
scope. Only four (S)-1-R ligands have been used in surized to the required H pressure and stirred with a mag-
this study, but a variety of analogues can be easily netic bar for the desired time at a controlled temperature
2
[
9a]
(
Æ28C). The reaction was stopped by release of pressure
synthesized,
opening the way to a search for the
and quenching of the solution with CH Cl at roomtemper-
ature. The crude materials were obtained by evaporation of
the solvent on a rotavapor. The product was finally analyzed
2
2
best complex for each substrate. Therefore, we hope
that the fine tuning of the complex stereoelectronic
properties, in particular by modification of the R
group, will lead to a more efficient asymmetric hydro-
genation of a large variety of simple ketones.
TM
by chiral GC (Supelco BETA DEX 225).
Acknowledgements
Experimental Section
We are grateful to the CNRS, the CNR, and the European
Union (HYDROCHEMRTN, contract HPRN-CT-2002–
00176) for funding.
General Remarks
All reactions were carried out under dry argon by using
Schlenk glassware and vacuum line techniques. Commercial
samples were used as received. Solvents were freshly distil-
1
13
1
31
31
1
led fromstandard drying agents. H,
C{ H, P} and P{ H}
A
H
R
U
G
NMR spectra were recorded on a Bruker Avance 500 instru-
ment operating at 500, 200, and 125 MHz, respectively.
Chemical shifts are reported in parts per million (ppm) rela-
References
[
1] a) Comprehensive Asymmetric Catalysis, Vols. 1–3,
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1
13
31
tive to Me Si ( H and C) or 85% H PO ( P). Mass spec-
4
3
4
tra were obtained on a Nermag R10–10 instrument (DCI,
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(
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(
APCI). Optical rotations were measured with a Perkin–
[
[
Elmer 241 polarimeter.
1
Synthesis of Complex 2-Bz
Complex 2-Bz was synthesized following the published pro-
[11a]
[9] 1
cedure
d=8.45 (br s, 2H, Ar), 7.64–7.60 (m, 3H, Ar), 7.43–7.38 (m,
H, Ar), 7.27–7.22 (m, 3H, Ar), 7.03–6.99 (m, 2H, Ar), 4.85
br d (AB syst.), JH,H =12 Hz, 1H, CH -Cp], 4.24 (dd, J
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3
[4] a) T. Ohkuma, H. Ooka, S. Hashiguchi, T. Ikariya, R.
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127, 8288.
5
[
=
H,H
2
2
1
.2 Hz, JH,H =1.5 Hz, 1H, subst Cp), 4.14 (t, JH,H =2.5 Hz,
H, subst Cp), 4.12 [d (AB syst.), JH,H =13,2 Hz, 1H, CH2-
Ph], 3.95 (m, 1H, subst Cp), 3.94 [d (AB syst.), JH,H
=
1
3.2 Hz, 1H, CH -Ph), 3.65(s, 5H, Cp), 3.62–3.56 (m, 2H,
2
CH/COD), 3.56–3.50 (m, 2H, CH/COD), 3.32 [br d (AB
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notti-Gerosa, Org. Lett. 2000, 2, 4173; b) J. P.
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Y. Fu, S.-F. Zhu, B.-M. Fan, H.-F. Duan, Q.-L. Zhou, J.
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syst.), JH,H =12 Hz, 1H, CH -Cp], 2.81–2.69 (m, 2H, CH /
2
2
COD), 2.18–2.03 (m, 4H, CH /COD), 1.47–1.36 (m, 2H,
2
13
1
CH /COD); C{ H} RMN (500 MHz, CDCl ): d=135.6 (d,
2
3
JC,P =14.3 Hz, Ar), 135.3 (s, quat Ar), 135.2 (d, JC,P =45 Hz,
quat Ar), 133.9 (d, JC,P =51.9 Hz, quat Ar), 131.7 (d, JC,P
.5 Hz, Ar), 130.6 (d, JC,P =3 Hz, Ar), 129.6 (s, Ar), 128.9 (s,
Ar), 128.8 (s, Ar), 128.0 (s, Ar), 127.8 (d, JC,P =10.4 Hz, Ar),
=
8
1
7
27.1 (d, JC,P =8.9 Hz, Ar), 87.8 (d, JC,P =18.8 Hz, quat Cp),
2.5 (d, JC,P =7.0 Hz, subst Cp), 72.4 (s, subst Cp), 70.7 (d,
JC,P =44.5 Hz, quat Cp), 70.5 (s, Cp), 68.8 (d, JC,P =4.6 Hz,
subst Cp), 66.12 (s, CH/COD), 63.40 (d, CH/COD, JC,P
4.7 Hz), 40.13(d, JC,P=5.7 Hz, CH Ph), 36.61 (d, J =3 Hz,
=
1
2
C,P
3
1
CH /COD), 31.1 (s, CH -Cp), 28.25 (s, CH /COD); P NMR
2
2
2
(
(
500 MHz, CDCl ): d=À9.00; MS (DCI, NH ): m/z=843
3
3
+
À
M+H , 2%); 807 (MÀCl , 28%).
312
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2007, 349, 309 – 313