Topics in Catalysis 13 (2000) 223–229 223 Application of heterogenized oxidation catalysts to reactions of terpenic and other olefins with H 2 O 2 Bert F. Sels, Aida L. Villa, Dirk Hoegaerts, Dirk E. De Vos and Pierre A. Jacobs ∗ Center for Surface Science and Catalysis, K.U. Leuven, Kardinaal Mercierlaan 92, 3001 Leuven, Belgium E-mail: pierre.jacobs@agr.kuleuven.ac.be This paper discusses two heterogeneous catalysts that were designed by covalent or electrostatic immobilization of a homogeneous metal complex. The first material contains Mn–triazacyclononane complexes anchored to silica. The second material is a resin with exchanged peroxo W polyoxoanions. Topics of interest include chemoselectivity, regioselectivity and recyclability. These aspects are studied in reactions with 18 different olefin substrates, with a focus on terpene reactions. Keywords: manganese, tungsten, hydrogen peroxide, terpenes, epoxidation, cis dihydroxylation 1. Introduction Heterogeneous oxidation catalysis is a much less mature technology than for instance heterogeneously catalyzed hy- drogenation. In the latter type of reactions, chemo- and enantioselectivity can be controlled rather well, even if the cheapest reductant, H 2 , is used. In contrast, the lack of reliable generic methodologies for oxidation often makes synthetic chemists recur to outdated methods. For epox- idation, a limited number of heterogeneous catalysts are available but these seldom meet all essential criteria, such as cheapness, use of a simple oxidant like H 2 O 2 , tolerance of other functional groups or applicability to a sufficient number of olefins. Even more work remains to be done for selective C–H activation, enylhydroperoxide formation or direct cis dihydroxylation of the double bond [1]. This particular situation calls for testing of newly re- ported oxidation catalysts on a sufficiently large number of potential starting products. Terpenes offer an excellent choice of substrates for functionalization of double bonds: • the double bonds vary broadly in electron density and steric accessibility; • two or more double bonds may be available, and this allows evaluation of intramolecular regioselectivity; • terpenes often contain a second oxidizable group such as an alcohol. The present paper discusses heterogeneous oxidation cata- lysts that we have recently designed in our group, and their applicability to terpene oxidation or oxidation of olefins in general. New data are presented for two materials: (1) a Mn catalyst containing an immobilized triazacyclononane lig- and [2], (2) a macroreticular resin with exchanged P–W peroxo anions [3]. ∗ To whom correspondence should be addressed. 2. Heterogenized Mn catalysts Mn oxidation chemistry has a few inherent advantages, such as the low price of Mn salts and their non-noxious na- ture. Moreover, as Mn is only a very weak Lewis acid, it hardly produces extra Brønsted acidity in solutions contain- ing H 2 O 2 , which is favorable for epoxide stability. How- ever, Mn needs a suitable ligand in order to adjust its re- dox potential. Extensive work has been performed in our lab with variously substituted 1,4,7-triazacyclononanes as a ligand [4]. In homogeneous catalysis, an optimized proce- dure was designed using oxalate as a co-catalyst and 1,4,7- trimethyl-1,4,7-triazacyclononane (tmtacn) as a ligand [5]. This method works particularly well for small, rather hy- drophilic and even electron-deficient olefins, such as allyl alcohol. Solid Mn–triazacyclononane catalysts can be obtained by synthesis of cationic Mn(tmtacn) 2+ in zeolite Y [6], or by covalent attachment of the related ligand 1,4-dimethyl- 1,4,7-triazacyclononane (dmtacn) to a functionalized silica material [2]. The latter approach is illustrated in figure 1. The silica surface may either first be functionalized with an epoxide-containing Si reagent, which then reacts with the secondary amine dmtacn (catalyst B). Alternatively, this re- action sequence may be reversed, starting with the reaction between dmtacn and the glycidylating agent (catalyst A). The eventual catalyst is obtained by chelation of Mn II by the immobilized ligand. Reaction with olefins and H 2 O 2 leads to the epoxide as the major product. However, a cis dihydroxylation product is formed as well, for instance from cis-2-hexene: (1) As was verified experimentally, this cis diol does not arise from solvolysis of the epoxide; such solvolysis should lead to a trans configuration. Rather, this Mn catalyst seems  J.C. Baltzer AG, Science Publishers