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J . Org. Chem. 1998, 63, 1408-1413
Meta l-Ca ta lyzed Oxid a tion s w ith P in a n e Hyd r op er oxid e: A
Mech a n istic P r obe To Distin gu ish betw een Oxom eta l a n d
P er oxom eta l P a th w a ys
H. E. B. Lempers, A. Ripolle`s i Garcia, and R. A. Sheldon*
Delft University of Technology, Department of Organic Chemistry and Catalysis, J ulianalaan 136,
2628 BL Delft, The Netherlands
Received J uly 14, 1997
The relative reactivities of tert-butyl hydroperoxide (TBHP) and pinane hydroperoxide (PHP) in
metal (Cr, Mo, Ru, Se, V, and Zr)-catalyzed oxidations were compared. When these oxidations
involve rate-limiting oxygen transfer from a peroxometal species to the substrate huge differences
between TBHP and PHP were observed, e.g., molybdenum-catalyzed epoxidation of cyclohexene
with TBHP gave a 98% yield while PHP gave 0%. When the reaction involves reaction of an
oxometal species with the substrate as the rate-limiting step, little or no difference is observed,
e.g., the selenium-catalyzed allylic oxidation of â-pinene gave a 96% and 99% yield with TBHP
and PHP, respectively. Small but significant differences are observed when reoxidation of the
catalyst by the hydroperoxide to the active oxometal species is the rate-limiting step; e.g., the
chromium-catalyzed oxidation of carveol gave carvone in 89% and 24% yield with TBHP and PHP,
respectively. Hence, the effect of RO2H structure on rate is dependent on the rate-limiting step.
Sch em e 1. P er oxom eta l vs Oxom eta l P a th w a ys
In tr od u ction
Metal-catalyzed oxidations with alkyl hydroperoxides
can be divided into two categories on the basis of the key
intermediate involved in the oxygen-transfer step: per-
oxometal or oxometal (Scheme 1).1
Molybdenum-2 and vanadium-catalyzed3 epoxidations
with alkyl hydroperoxides have been extensively studied,
and there is general agreement that these reactions
involve an alkylperoxometal (MoVI or VV) complex as the
active oxidant.3g,4 The molybdenum-catalyzed epoxida-
tion of propylene with tert-butyl hydroperoxide (TBHP)
or ethylbenzene hydroperoxide is used industrially for
the manufacture of propylene oxide.5 Catalytic oxida-
tions with selenium,6 ruthenium,7 osmium,8 and chro-
mium,9 on the other hand, are generally believed to
involve oxometal species as the active oxidant.
We became interested in the use of pinane hydroper-
oxide (PHP) as an oxidant on the basis of its commercial
availability from the autoxidation of pinane.10 Catalytic
reduction to pinanol and subsequent pyrolysis affords
linalool, which has applications in flavors and fragrances
and vitamin E synthesis.10 We were interested, there-
fore, to see if the active oxygen in PHP could be utilized
in a catalytic oxidation rather than “sacrificed” in cata-
lytic reduction. An obvious application was in the
catalytic epoxidation of olefins, and we were particularly
interested in the epoxidation of styrene, as the product
is of interest as a precursor to the flavor chemical,
2-phenylethanol.
* To whome correspondence should be addressed.
(1) (a) Sheldon, R. A. CHEMTECH 1991, 566. (b) Sheldon, R. A.
Top. Curr. Chem. 1993, 164, 21. (c) Sheldon, R. A.; Dakka, J . Catal.
Today 1994, 19, 215.
(2) (a) Sheldon, R. A. In Aspects of Homogeneous Catalysis Ugo, R.,
Ed.; Riedel: Dordrecht, 1981; Vol. 4, pp 3-70. (b) Sheldon, R. A. Rec.
Trav. Chim. Pays-Bas 1973, 92, 253. (c) Sheldon, R. A. Rec. Trav. Chim.
Pays-Bas 1973, 92, 367. (d) Sapunov, V. N. J . Mol. Catal. 1980, 7, 149.
(e) Sheldon, R. A.; van Doorn, J . A.; Schram, C. W. A.; de J ong, A. J .
J . Catal. 1973, 31, 438. (f) Trost, M. K.; Bergman, R. G. Organome-
tallics 1991, 10, 1172. (g) Sobczak, J .; Ziolkowski, J . J . Inorg. Chim.
Acta 1976, 19, 15. (h) Trifiro, F.; Forzatti, P.; Preite, S.; Pasquon, I. J .
Less-Common Metals 1974, 36, 319. (i) Dawoodi, Z.; Kelly, R. L.
Polyhedron 1986, 5, 271. (j) Howe, G. R.; Hiatt, R. R. J . Org. Chem.
1971, 36, 2493. (k) Sheng, M. N.; Zajacek, J . G. J . Org. Chem. 1970,
35, 1839. (l) Gavrilenko, V. A.; Evzerikhin, E. I.; Moiseev, I. I. Izv.
Akad. Nauk, Ser. Khim. 1977, 1266 and references therein. (m)
Gavrilenko, V. A.; Evzerikhin, E. I.; Fish, I. S.; Moiseev, I. I. Izv. Akad.
Nauk, Ser. Khim. 1977, 2172. (n) Moiseev, I. I. J . Mol. Catal., in press.
(3) Michaelson, R. C.; Palermo, R. E.; Sharpless, K. B. J . Am. Chem.
Soc. 1977, 99, 1990. (b) Itoh, T.; Kaneda, K.; Teranishi, S. J . Chem.
Soc., Chem. Commun. 1976, 421. (c) Tanaka, S.; Yamamoto, H.; Nozaki,
H.; Sharpless, K. B.; Michaelson, R. C.; Cutting, J . D. J . Am. Chem.
Soc. 1974, 96, 5254. (d) Mihelich, E. D. Tetrahedron Lett. 1979, 49,
4729. (e) Takai, K.; Oshima, K.; Nozaki, H. Bull. Chem. Soc. J pn. 1983,
56, 3791. (f) Mihelich, E. D.; Daniels, K.; Eickhoff, D. J . J . Am. Chem.
Soc. 1981, 103, 7690. (g) Gould, E. S.; Hiatt, R. R.; Irwin, K. C. J . Am.
Chem. Soc. 1968, 90, 4573.
Resu lts a n d Discu ssion
Our attempts to epoxidize styrene with PHP in the
presence of Mo(CO)6 as catalyst afforded no epoxide. We
(5) Valbert, J . R.; Zajacek, J . G.; Orenbuch, D. I. In Encyclopedia of
Chemical Processing and Design; McKeth, J ., Ed.; Marcel Dekker: New
York, 1993; pp 88-137.
(6) Umbreit, M. A.; Sharpless, K. B. J . Am. Chem. Soc. 1977, 99,
5526.
(4) (a) Mimoun, H.; Mignard, M.; Brechot, P.; Saussine, L. J . Am.
Chem. Soc 1986, 108, 3711. (b) Sheldon, R. A.; van Doorn, J . A. J .
Catal. 1973, 31, 427. (c) Su, C.-C.; Reed, J . W.; Gould, E. S. Inorg.
Chem. 1973, 12, 337. (d) Baker, T. N.; Mains, G. J .; Sheng, M. N.;
Zajacek, J . G. J . Org. Chem. 1973, 38, 1145. (e) Chong, A. O.; Sharpless,
K. B. J . Org. Chem. 1977, 42, 1587.
(7) Che, C.-M. Pure Appl. Chem. 1995, 2, 225.
(8) Lohray, B. B.; Bhushan, V.; Kumar, R. K. J . Org. Chem. 1994,
59, 1375.
(9) Muzart, J . Chem. Rev. (Washington, D.C.) 1992, 92, 113.
(10) Ullman’s Encyclopedia of Industrial Chemistry, 4th ed.; VCH
Verlagsgesellschaft: Weinheim, Germany, 1981; Vol. 20, p 199.
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