Notes and references
{ Data for crystal structure analysis were measured on a Nonius
KappaCCD diffractometer. 2a: C21H19NO3S monoclinic, P21/n (No. 14),
a 5 12.6115(1), b 5 5.9741(1), c 5 24.2313(2) s, b 5 101.681(1)u,
V 5 1787.83(4) s3, Z 5 4, T 5 123 K, m(MoKa) 5 0.202 mm21, 32585
reflections, 4091 unique reflections (2hmax 5 50u), R1 5 0.0320 [I . 2s(I)],
wR2 5 0.0906 (all data), 239 parameters and 1 restraint. Empirical
suppdata/cc/b5/b505278p/index.sht for crystallographic data in CIF or
other electronic format.
Scheme 4 Synthesis of enantiopure 2-amino ketone 2a from diamine 10.
standard AA reaction11 followed by enantiomeric enrichment
through crystallisation (99% ee). In an analogous manner,
(R,R)-1,2-diphenyl-2-tosylaminoethanol gave (R)-2a in 99% ee.
In addition, NMO proved an optimum oxidant regarding
the chemoselectivity within the final oxidation. Thus, within the
competing ketone vs. imine oxidation at the stage of the
intermediate D, no benzil formation was detected in the formation
of 2a or 2b and the compounds 6b and 7 were equally formed with
complete chemoselectivity and in high yields.
1 M. Hanada, K. Sugawara, K. Koko, S. Toda, Y. Nishiyama,
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10 For an example of a different overoxidation in a related carbamate-
based aminohydroxylation: Z. Liu, N. Ma, Y. Jia, M. Bois-Choussy,
A. Malabarba and J. Zhu, J. Org. Chem., 2005, 70, 2847.
11 G. Li, H.-T. Chang and K. B. Sharpless, Angew. Chem., Int. Ed. Engl.,
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14 An alternative synthesis of 2-amino ketones through Os-catalysed
aminohydroxylation of silyl enol ethers was reported previously:
P. Phukan, Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem.,
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1998, 9, 1001.
Enantiopure 2-amino ketones 8, 9 were obtained from trans-
configured amino alcohol precursors. These results demonstrate
the high efficiency of the present process since the NMO-based
reaction in Scheme 3 leads to high chemoselectivity in the
oxidation of the amino alcohols, generally without any detectable
degree of racemisation or overoxidation
Interestingly, the reaction was also found to proceed with a
vicinal diamine. Application of symmetrically bis-tosylated
(R,R)-ethylenediamine 10 led to enantiomerically pure (R)-2a.
The reaction was significantly slower than for related amino
alcohols and was carried out at 50 uC (Scheme 4), yielding 59% of
2a after a period of 48 h. This result agrees well with the
observation from ketamination reactions which showed a kinetic
oxidation preference for alcohol over tosylamido groups and
thereby supports the mechanistic hypothesis outlined in Figs. 2
and 3.
To summarise, we have described a new osmium-catalysed
oxidation of alkenes, which yields 2-amino ketones from alkenes
under mild conditions. The reaction can either be carried out as a
direct ketamination or, alternatively, as a sequential process which
consists of asymmetric aminohydroxylation and subsequent
oxidation. The latter variant conveniently leads to enantiopure
2-amino ketones.
The overall development of the reaction represents the first
successful alteration of an established osmium catalytic protocol
toward alternative product formation. We expect future investiga-
tion of imido osmium compounds and catalysts to devise further
new reactivity in this area.
The present work was generously supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen Industrie
within the VCI. The authors thank Prof. Dr K. H. Do¨tz for his
support, and A. V. is grateful to the Spanish Ministerio de
Educacio´n y Ciencia for a visiting fellowship.
15 The kinetic stability of the bis(azaglycolate)s C and D is decisive. It is
based on the singular character of the sulfonyl moiety. Alternative
substituents, as obtained from carbamate- and acetamide-based
nitrenoids, lead to enhanced hydrolysis and therefore to diminished
formation of amino ketones.
Amparo Villar,a Claas H. Ho¨velmann,a Martin Niegerb and
Kilian Mun˜iz*a
16 For a related mechanistic study on undesired formation of 2-hydroxy
ketones under OsO4-catalysis, see: B. B. Lohray, V. Bhushan and
R. K. Kumar, J. Org. Chem., 1994, 59, 1375.
17 Recent work by Plietker has introduced a ruthenium-catalysed
ketohydroxylation of olefins. Interestingly, the postulated catalytic
cycles differ substantially from those of our Os-catalysis: B. Plietker and
M. Niggemann, Org. Biomol. Chem., 2004, 2403; B. Plietker, J. Org.
Chem., 2004, 69, 8287; B. Plietker, Eur. J. Org. Chem., 2005, 1919.
aKekule´-Institut fu¨r Organische Chemie und Biochemie,
Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany.
E-mail: kilian.muniz@uni-bonn.de; Fax: +49 228 735813;
Tel: +49 228 736553
bInstitut fu¨r Anorganische Chemie, Gerhard-Domagk-Str. 1,
D-53121 Bonn, Germany. E-mail: nieger@joyx.joensuu.fi
3306 | Chem. Commun., 2005, 3304–3306
This journal is ß The Royal Society of Chemistry 2005