A Heterogeneous cis-Dihydroxylation Catalyst with Stable, Site-Isolated Osmium-Diolate Reaction Centers

Abstract

Involatile OsO4! A tetrasubstituted olefin is immobilized on SiO2 and reacts with OsO4 to form a stable osmate(IV) ester (see scheme), which is a leak‐proof heterogeneous catalyst for the cis‐dihydroxylation of olefins.

Osmium silsesquioxane as model compound and homogeneous catalyst for the dihydroxylation of alkenes

“…1. This silica-supported Os-catalyst proved to be active in the dihydroxylation of a number of alkenes with N-methylmorpholine-N-oxide (NMO) as the oxidant [9,11] (NMO may be regenerated by oxidation with H 2 O 2 ) [10]. Careful heterogeneity tests confirmed the absence of OsO 4 leaching.…”

“…Recently, Jacobs and co-workers reported an efficient and robust heterogeneous catalyst obtained by binding OsO 4 to a tetrasubstituted olefin covalently linked to a silica support [9,10]. The tetrasubstituted diolate ester which was obtained at one side of the osmium centre provided a stable connection between the osmium centre and the silica support, since it does not undergo hydrolysis under the reaction conditions applied.…”

Recent Developments in Metal‐Catalyzed Dihydroxylation of Alkenes

“…The tetrasubstituted diolate ester which is formed at one side of the Os atom is stable, and keeps the catalyst fixed on the support material. The catalytic reaction can take place at the free coordination sites of Os (Scheme 1.17) [44].…”

Aerogel Supported Nanoparticles in Catalysis

“…The high cost, toxicity, and possible contamination of osmium catalysts in the products restrict the use in industry. Heterogenization via microencapsulation (OsO 4 was immobilized into polystyrene, see entry 1 of Table 5.1 ) [41] , covalent anchoring (addition of OsO 4 to a tetrasubstituted olefi n that is covalently linked to a silica support, followed by reoxidation, (see entries 2 and 3 of Table 5.1 ) [42] , and use of ionic liquids (OsO 4 -DMAP complex is soluble in [bmim]PF 6 , see entries 4 -6 of Table 5.1 ) [43] has been used in order to address this problems.…”