ChemComm
Communication
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V. Banphavichit, Y. Zhu and K. Burgess, Chem.–Eur. J., 2007, 13, 7162.
3 For examples of Rh- and Ru-complex catalysed asymmetric hydro-
genation of 2-substituted-2-alkenols, see: (a) K. Iseki, Y. Kuroki,
T. Nagai and Y. Kobayashi, Chem. Pharm. Bull., 1996, 44, 477;
It is not difficult to understand that the H-bonding interactions
might be retained in the solvents without a H-bonding donor or
receptor such as DCM and DCE but in the protic solvents such
as MeOH, EtOH and i-PrOH or the solvents with a H-bonding
receptor such as THF and EtOAc, this kind of hydrogen bonding
could be destroyed by the solvents and consequently decrease the
enantioselectivity and activity. Secondly, in accord with the postulate
of a hydrogen-bonding secondary interaction, the ChenPhos–Rh
complex is inactive for the hydrogenation of the similar substrates
without a hydrogen-bonding donor, and, among the tested eight
diphosphine ligands, only the ligands containing appropriately
oriented dimethylamino groups (H-bonding receptors) show high
enantioselectivity in the hydrogenation of 2-methyl-3-phenyl-2-
propenol 1a. Hydrogen-bonding interactions have been utilised to
account for some metal-catalysed asymmetric transformations,10 but
are rare in the enantioselective hydrogenation.11 This strategy might
prove to be useful in the development of novel catalysts for the
asymmetric hydrogenation of some challenging substrates.
¨
(b) M. Banziger, J. Cercus, H. Hirt, K. Laumen, C. Malan,
F. Spindler, F. Struber and T. Troxler, Tetrahedron: Asymmetry,
2003, 14, 3469; (c) F. Spindler, C. Malan, M. Lotz, M. Kesselgruber,
U. Pittelkow, A. Rivas-Nass, O. Briel and H.-U. Blaser, Tetrahedron:
Asymmetry, 2004, 15, 2299; (d) J. Wassenaar, M. Kuil and
J. N. H. Reek, Adv. Synth. Catal., 2008, 350, 1610; (e) M. Qiu, D.-Y.
Wang, X.-P. Hu, J.-D. Huang, S.-B. Yu, J. Deng, Z.-C. Duan and
Z. Zheng, Tetrahedron: Asymmetry, 2009, 20, 210.
4 (a) W. Tang and X. Zhang, Chem. Rev., 2003, 103, 3029; (b) W. Zhang,
Y. Chi and X. Zhang, Acc. Chem. Res., 2007, 40, 1278.
5 A. Lighfoot, P. Schnider and A. Pfaltz, Angew. Chem., Int. Ed., 1998,
37, 2897.
6 For recent reviews on the Ir-complex catalysed asymmetric hydrogena-
tion, see: (a) S. J. Roseblade and A. Pfaltz, Acc. Chem. Res., 2007, 40, 1402;
(b) T. L. Church and P. G. Andersson, Coord. Chem. Rev., 2008, 252, 513;
`
(c) X. Cui and K. Burgess, Chem. Rev., 2005, 105, 3272; (d) O. Pamies,
´
P. G. Andersson and M. Dieguez, Chem.–Eur. J., 2010, 16, 14232;
(e) D. H. Woodmansee and A. Pfaltz, Chem. Commun., 2011, 47, 7912.
7 For some representative examples of the asymmetric hydrogenation
of 2-methyl-3-phenyl-2-propenol catalysed by chiral Ir-complexes,
see: (a) S. P. Smidt, F. Menges and A. Pfaltz, Org. Lett., 2004, 6, 2023;
(b) K. Kaellstroem, C. Hedberg, P. Brandt, A. Bayer and P. G.
Andersson, J. Am. Chem. Soc., 2004, 126, 14308; (c) C. Hedberg,
K. Kaellstroem, P. Brandt, L. K. Hansen and P. G. Andersson, J. Am.
Chem. Soc., 2006, 128, 2995; (d) X. Li, L. Kong, Y. Gao and X. Wang,
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and O. K. Sang, Synlett, 2009, 771; ( f ) J. Mazuela, A. Paptchikhine,
The application of the enantioselective hydrogenation was
demonstrated in the first asymmetric synthesis of antifungal
agent (À)-amorolfine (see ESI†).
In summary, a highly enantioselective hydrogenation of a variety
of 2-substituted-2-alkenols catalysed by a ChenPhos–Rh complex has
been developed. To the best of our knowledge, the ChenPhos–Rh
complex is the most enantioselective catalyst system for the
asymmetric hydrogenation of a broad range of 2-substituted-2-
alkenols reported so far, probably due to a hydrogen-bonding
secondary interaction of the dimethylamino unit of the ligand
with the hydroxyl group of the substrate. Optically active
antifungal agent amorolfine was first synthesised using the
enantioselective hydrogenation as the key step. Further studies
to explore the application of this methodology in the synthesis
of bioactive compounds are underway in our lab.
`
´
O. Pamies, P. G. Andersson and M. Dieguez, Chem.–Eur. J., 2010,
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`
´
(i) J. Mazuela, O. Pamies, M. Dieguez, P.-O. Norrby and P. G.
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`
´
hedron, 2011, 67, 5421; (l) J. Margalef, O. Pamies, M. Dieguez,
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¨
(m) K. Bert, T. Noel, W. Kimpe, J. L. Goeman and J. Van der Eycken,
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`
´
Chim. Acta, 2012, 95, 2176; (o) M. Coll, O. Pamies and M. Dieguez,
`
Adv. Synth. Catal., 2013, 355, 161; (p) J. Mazuela, O. Pamies and
We thank Prof. Q.-L. Zhou’s group in Nankai University for
sharing the hydrogenation facilities, Solvias AG for providing
the Ligand Kit, and the National Natural Science Foundation of
China (21272271, 21172262, 21002122) for financial support.
´
M. Dieguez, Eur. J. Inorg. Chem., 2013, 2139.
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9 High enantioselectivities of up to 98% ee were achieved in the BINAP-Ru
complex catalysed asymmetric hydrogenation of geraniol and nerol, see:
H. Takaya, T. Ohta, N. Sayo, H. Kumobayashi, S. Akutagawa, S. Inoue,
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Notes and references
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980 | Chem. Commun., 2014, 50, 978--980
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