Ruthenium(III-VII) compounds
RuCl3 - the most used reagent - is used mainly catalytically in oxidation reactions. By means of stoichiometric quantities of an oxidizing agent such as Oxone or NaIO4 it is oxidized in catalytic cycles to ruthenium tetroxide. RuO4 reacts similar to OsO4, but with a smaller efficiency. However, the use of Ru compounds as reagents is clearly cheaper.
See also: TPAP
Recent Literature
An improved protocol for the RuO4-catalyzed syn-dihydroxylation
uses only 0.5 mol% catalyst under acidic conditions. Various olefins can be
hydroxylated in good to excellent yields with only minor formation of side
products.
B. Plietker, M. Niggemann, Org. Lett., 2003, 3353-3356.
An efficient oxidant-free oxidation for a wide range of alcohols was
achieved by a recyclable ruthenium catalyst, which was prepared from readily
available reagents through nanoparticle generation and gelation.
W.-H. Kim, I. S. Park, J. Park, Org. Lett.,
2006, 8, 2543-2545.
Specific oxidation protocols have been developed for the cleavage of styrenes,
aliphatic olefins, and terminal aliphatic olefins to carbonyl compounds with
ruthenium trichloride as catalyst. Olefins that are not fully substituted are
converted to aldehydes rather than carboxylic acids.
D. Yang, C. Zhang, J. Org. Chem., 2001, 66, 4814-4818.
A catalytic amount of a composite material, RuO2/BaTi4O9,
in combination with NaIO4 in EtOAc-H2O has been shown to
efficiently cleave alkenes, affording ketones, aldehydes and/or carboxylic acids
in high yields.
H. Okumoto, K. Ohtsuko, S. Banjoya, Synlett, 2007,
3201-3205.
D. Yang, C. Zhang, J. Org. Chem., 2001, 66,
4814-4818.
A new mild RuO4-catalyzed
ketohydroxylation of olefins is reported. α-Hydroxy ketones were
obtained with high regioselectivity and in good to excellent yields.
B. Plietker, J. Org. Chem., 2003, 68, 7123-7125.
A two-step sequence of asymmetric dihydroxylation and regioselective monooxidation gave
enantiopure α-hydroxy ketones (acyloins). The combination of RuCl3/Oxone/NaHCO3
was used in the first catalytic regioselective oxidation of vic-diols
to α-ketols.
B. Plietker, Org. Lett., 2004, 6, 289-291.
An efficient method for the
oxidative cleavage of internal and terminal alkynes to carboxylic acids
using a combination of RuO2/Oxone/NaHCO3 in a CH3CN/H2O/EtOAc
solvent system is described. Various alkynes, regardless of their
electron density, were oxidized to carboxylic acids in excellent yield.
D. Yang, F. Chen, Z.-M. Dong, D.-W. Zhang, J.
Org. Chem., 2004, 69, 209-212.
A highly
enantioselective and catalytic vinylation of aldehydes leads to allylic alcohols
that are then transformed to the allylic amines via Overman's [3,3]-sigmatropic
rearrangement of imidates. Oxidative cleavage of the allylic amines furnishes amino acids in good yields and excellent ee's. The scope and utility of this
method are demonstrated by the synthesis of challenging allylic amines and their
subsequent transformation to valuable nonproteinogenic amino acids, including
both D and L configured (1-adamantyl)glycine.
Y. K. Chen. A. E. Lurain, P. J. Walsh, J. Am. Chem. Soc., 2002,
124, 12225-12231.
RuCl3-catalyzed oxidative cyanation of tertiary amines with sodium
cyanide under molecular oxygen at 60°C gives the corresponding α-aminonitriles
in excellent yields. This reaction is clean and should be an environmentally
benign and useful process.
S.-I. Murahashi, N. Komiya, H. Terai, T. Nakae, J. Am. Chem. Soc.,
2003,
125, 15312-15313.
A novel, high-yielding method for sulfation of alcohols proceeds via
sulfite- and sulfate diester intermediates. Sulfite diesters serve as
versatile sulfate monoester precursors, that allow interesting
transformations.
M. Huibers, I. Manuzi, F. P. J. T. Rutjes, F. L. van Delft, J. Org. Chem., 2006,
71, 7473-7476.
A facile ruthenium-catalyzed methodology for the preparation of pentavalent
iodine compounds uses peracetic acid as an oxidant. The new procedure allows the
preparation of iodylarenes bearing strongly electron-withdrawing groups.
A. Y. Koposov, R. R. Karimov, A. A. Pronin, T. Skrupskaya, M. S. Yusubov, V. V.
Zhdankin, J. Org. Chem., 2006,
71, 9912-9914.