3
Table 2 Oxygenation of lower alkanes (H
2
O
2
= 1 mol dm2 , OsCl
3
= 1 3
may produce a catalytically active oxo species surrounded with
voluminous ligands, and the relatively high bond- and stereo-
selectivities of the alkane oxidation may be due in this case to
the bulkiness of the ligands at the reaction centre.
We thank the Russian Basic Research Foundation and the
Swiss National Science Foundation for support.
23
23
23
4
10
mol dm , py = 0.125 mol dm ; MeCN 80 °C, 1.5 h)
Alkane
pressure/bar)
3
(
Products/mol dm2
OH (0.017); HCHO (3.0 3 10–5)
Methane (40)
Ethane (20)
Propane (6)
CH
CH
CH
CH
CH
3
3
3
3
3
CHO (0.08); CH
CH CHO (0.034); CH
CH(OH)CH (0.018); CH
CHO (0.011); CH
CH(OH)CH CH
CH OH (0.002)
3 2
CH OH (0.022)
2
3
COCH
CH
3
(0.054);
CH
COCH
(0.011);
3
3
2
2
OH (0.044)
CH
Notes and references
n-Butane (2)
CH
CH
2
CH
2
3
2
3
(0.026); CH
3
2
3
1 (a) A. E. Shilov and G. B. Shul’pin, Activation and Catalytic Reactions
of Saturated Hydrocarbons in the Presence of Metal Complexes, Kluwer,
Dordrecht, 2000; (b) A. E. Shilov and G. B. Shul’pin, Chem. Rev., 1997,
CH
3
2
CH
2
2
9
7, 2879; (c) R. H. Crabtree, Chem. Rev., 1995, 95, 987; (d) G. B.
Table 3 Selectivities of alkane oxidations by various systems
Shul’pin, Organic Reactions Catalysed by Metal Complexes, Nauka,
Moscow, 1988.
Substrate
System
Selectivitya
2 Reviews: T. Wirth, Angew. Chem., Int. Ed., 2000, 39, 334; R. A. Sánchez-
Delgado, M. Rosales, M. A. Esteruelas and L. A. Oro, J. Mol. Catal. A:
Chem., 1995, 96, 231; Y. Gao, in Encyclopedia of Reagents for Organic
Synthesis, ed. L. A. Paquette, J. Wiley & Sons, Chichester, 1995, vol. 6,
pp. 3801–3810; H. C. Kolb, K. B. Sharpless and M. S. Van Nieuwenhze,
Chem. Rev., 1994, 94, 2483; Catalytic Oxidations with Hydrogen
Peroxide as Oxidant, ed. G. Strukul, Kluwer, Dordrecht, 1992; K. A.
Jørgensen, Chem. Rev., 1989, 89, 431; A. H. Haines, Methods for the
Oxidation of Organic Compounds, Academic Press, London, 1985; M.
Schroeder, Chem. Rev., 1980, 80, 187; Oxidation, ed. R. L. Augustine,
Marcel Dekker, Inc., New York, 1969.
3 Recent original papers: P. C. B. Page, M. J. MacKenzie and D. R. Burkle,
Tetrahedron, 1998, 54, 14 581; K. Bergstad, J. J. N. Piet and J.-E.
Bäckvall, J. Org. Chem., 1999, 64, 2545; A. J. Pearson and I. B. Neagu,
J. Org. Chem., 1999, 64, 2890; T. J. Donohoe, K. Blades, M. Helliwell,
P. R. Moore and J. J. G. Winter, J. Org. Chem., 1999, 64, 2980; P.
Barthazy, M. Wörle and A. Mezetti, J. Am. Chem. Soc., 1999, 121, 480;
K. S. Coleman, M. Coppe, C. Thomas and J. A. Osborn, Tetrahedron
Lett., 1999, 40, 3723; J. Eames, H. J. Mitchell, A. Nelson, P. O’Brien, S.
Warren and P. Wyatt, J. Chem. Soc., Perkin Trans. 1, 1999, 1095; F.
Ahmed, E. H. Al-Mutairi, K. L. Avery, P. M. Cullis, W. U. Primrose,
G. C. K. Roberts and C. L. Willis, Chem. Commun., 1999, 2049; W. A.
Herrmann, R. M. Kratzer, J. Blümel, H. B. Friedrich, R. W. Fischer, D. C.
Apperley, J. Mink and O. Berkesi, J. Mol. Catal. A: Chem., 1997, 120,
197.
The oxidations of higher hydrocarbons were carried out in air in
thermostated Pyrex cylindrical vessels with vigorous stirring. The total
volume of the reaction solution was 5 or 10 mL. In a typical experiment,
initially, a portion of 35% aqueous solution of hydrogen peroxide (Fluka)
was added to the solution of the catalyst, substrate and heterocycle in
acetonitrile (Fluka). The oxidations of lower alkanes were carried out in
an stainless steel autoclave with intensive stirring (volume of the reaction
solution was 5 mL and total volume of autoclave was 100 mL). Before the
oxidation the autoclave was charged with the alkane under appropriate
pressures. The reactions were stopped by cooling with ice and the
reaction solution was analysed by GC (DANI-86.10; fused silica
capillary column 25 m 3 0.32 mm 3 0.25 mm, CP-WAX52CB;
integrator SP-4400). Comparison of the chromatograms of the reaction
n-Heptane
C(1)+C(2)+C(3)+C(4)
1.0+7.3+6.3+8.1
H
H
H
2
2
2
O
O
O
2
2
2
–hn in MeCN
–FeSO
–OsCl
4
in MeCN–H
in MeCN
2
O
O
1.0+5.0+4.8+4.6
3
1.0+11.8+9.8+3.5
2,2,4-Trimethyl-
pentane
1°+2°+3°
1.0+1.75+6.2
1.0+2.75+6.0
H
2
H
2
H
2
H
2
H
2
O
2
O
2
O
2
O
2
O
2
–hn in MeCN
–FeSO in MeCN–H
–Bu NVO
4
2
4
3
–PCA in MeCN 1.0+3.0+4.8
–OsCl
–OsCl
3
in MeCN
1.0+2.2+8.7
1.0+2.1+18.3
3
in MeCN–py
23
(0.125 mol dm )
cis-Decalin
trans/cis
1.3
1.9
H
H
H
H
H
2
2
2
2
2
O
O
O
O
O
2
2
2
2
2
–hn in MeCN
–hn in py
–FeSO
–Bu NVO
–OsCl in MeCN–py
4
in MeCN–H
2
O
3.4
4
3
–PCA in MeCN 2.1
3
1.2
23
(
H
0.125 mol dm
–OsCl in MeCN–py
)
2
O
2
3
0.56
0.26
23
(6.25 mol dm
)
H
2
O
2
–OsCl in MeCO H
3
2
a
Parameter C(1)+C(2)+C(3) is normalized (i.e. calculated taking into
account the number of hydrogen atoms at each position) relative reactivities
of hydrogens at carbon atoms 1, 2 and 3 of the alkane chain, respectively;
parameter 1°+2°+3° is normalized relative reactivities of hydrogen atoms at
primary, secondary and tertiary carbons, respectively; parameter trans/cis =
4
[trans-decal-9-ol]/[cis-decal-9-ol], where [trans- and cis-decal-9-ol] are
concentrations of trans- and cis-decal-9-ol formed in the oxidation,
respectively.
pyridine the reaction becomes more selective, the trans/cis ratio
decreasing with increasing pyridine concentration. It is im-
portant to note that in MeCO
value of the trans/cis parameter (0.26) and the parameter RCcis
100(ccis 2 ctrans)/(ccis + ctrans) = 58%. The value of the
trans/cis parameter for the system ‘H –OsCl ’ in MeCO H is
only slightly higher than that (trans/cis = 0.12) for the
2
H the reaction exhibits a high
3
samples before and after their treatment with PPh (for this method, see
=
refs. 1(a),(b),5–8) demonstrated that concentrations of alkyl hydro-
peroxides were very low. The concentration of formaldehyde was
measured spectrophotometrically after its transformation into 2,6-dime-
2
O
2
3
2
IV
thyl-3,5-diacetyl-1,4-dihydropyridine as described previously.
6
2 2 3
hydroxylation in MeCN by the system ‘H O –LMn (O) -
IV
+
5 G. B. Shul’pin, M. M. Bochkova and G. V. Nizova, J. Chem. Soc., Perkin
Trans. 2, 1995, 1465; G. B. Shul’pin, G. V. Nizova and Yu. N. Kozlov,
New. J. Chem., 1996, 20, 1243.
2
Mn L –MeCO H (L = 1,4,7-trimethyl-1,4,7-triazacyclono-
nane)’ described recently.8
On the basis of the results obtained and especially taking into
account the selectivity parameters, one may assume that
oxidation by the system H O –OsCl starts with hydrogen atom
2 2 3
6
G. V. Nizova, G. Süss-Fink and G. B. Shul’pin, Chem. Commun., 1997,
3
5
97; G. V. Nizova, G. Süss-Fink and G. B. Shul’pin, Tetrahedron, 1997,
3, 3603; G. Süss-Fink, G. V. Nizova, S. Stanislas and G. B. Shul’pin,
abstraction from the alkane by an oxo osmium complex, and the
reaction occurs in a solvent cage. The alkyl radicals formed
react then with dioxygen to generate the corresponding alkyl
hydroperoxide which decomposes to afford the corresponding
ketone and alcohol. The system described here can be
considered as a model for the oxidations of C–H compounds
catalysed by iron-containing enzymes, osmium being an iron
homologue in the Periodic System. Indeed, oxidations with
participation of cytochrome P-450, methane monooxygenase
and chloroperoxidase are believed to begin with hydrogen atom
abstraction by a high-valent iron oxo species.1 Coordination of
a nitrogen-containing heterocycle (and/or acetate) to osmium
J. Mol. Catal. A: Chem., 1998, 130, 163.
7 G. B. Shul’pin, D. Attanasio and L. Suber, J. Catal., 1993, 142, 147; G.
V. Nizova and G. B. Shul’pin, Russ. Chem. Bull., 1994, 43, 1146; G. B.
Shul’pin, M. C. Guerreiro and U. Schuchardt, Tetrahedron, 1996, 52,
1
3 051; M. C. Guerreiro, U. Schuchardt and G. B. Shul’pin, Russ. Chem.
Bull., 1997, 46, 749.
J. R. Lindsay Smith and G. B. Shul’pin, Tetrahedron Lett., 1998, 39,
8
9
4
4
909; G. B. Shul’pin and J. R. Lindsay Smith, Russ. Chem. Bull., 1998,
7, 2379; G. B. Shul’pin, G. Süss-Fink and J. R. Lindsay Smith,
Tetrahedron, 1999, 55, 5345.
F. Hino and D. Dolphin, Chem. Commun., 1999, 629; K. Chen and L.
Que, Jr., Chem. Commun., 1999, 1375; E. Baciocchi, O. Lanzalunga and
L. Manduchi, Chem. Commun., 1999, 1715.
,9
1132
Chem. Commun., 2000, 1131–1132