Efficient, regioselective epoxidation of dienes with hydrogen peroxide catalyzed by [γ-SiW10O34(H2O)2]4−

Molecular Design of Polyoxometalate-Based Compounds for Environmentally-Friendly Functional Group Transformations: From Molecular Catalysts to Heterogeneous Catalysts

“…The epoxidation of 3-substituted cyclohexenes such as 3-methyl-1-cyclohexene and 2-cyclohexen-1-ol showed unusual diastereoselectivities; the epoxidation diastereoselectively gave the corresponding epoxides with oxirane ring trans to the substituents, i.e., anti configuration. Further, it is noted that more accessible, but less nucleophilic double bonds in non-conjugated dienes such as trans-1,4-hexadiene, [17,20,21]. Such unique stereospecificity, diastereoselectivity, and regioselectivity with 2 have never been reported so far [20,21].…”

“…The tetra-nbutylammonium (TBA) salt of a protonated divacant silicodecatungstate, (TBA) 4 [c-SiW 10 O 34 (H 2 O) 2 ] (1, Fig. 1), efficiently catalyzed oxygen-transfer reactions (mono-oxygenation-type reactions) of various substrates including olefins, allylic alcohols, sulfides, and organosilanes with an aqueous H 2 O 2 [16][17][18][19]. The high yields and efficiencies of H 2 O 2 utilization were achieved for epoxidation of various terminal, internal, and cyclic olefins (typically C99%, Fig.…”

Green Oxidation Reactions by Polyoxometalate-Based Catalysts: From Molecular to Solid Catalysts

“…For the non-conjugated dienes, V showed the specific regioselectivity different from those of peroxotungstates and stoichiometric oxidants such as dimethyldioxirane and m-chloroperoxybenzoic acid. For the epoxidation of 1-methyl-1,4-cyclohexadiene, the ratio of 4,5-epoxide to total epoxides was 0.89 and the more accessible, but less nucleophilic double bond was much more selectively epoxidized [20]. For the epoxidation of primary allylic alcohols, the corresponding epoxy alcohols were selectively obtained with small amounts of a,b-unsaturated aldehydes [21].…”

“…Recently, we have successfully developed highly atomefficient catalytic green oxidation systems with H 2 O 2 or O 2 as an oxidant by precise design and synthesis of novel POM-based molecular catalysts [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The organic-inorganic hybrid support has been synthesized by covalently anchoring N-octyldihydroimidazolium cation fragments onto SiO 2 and the POM-based molecular catalysts can be immobilized on the modified support via the anion exchange [28,29].…”

Hydrolytic and Peroxyhydrolytic Degradation of Nerve Agent Analogs with Low Molecular Weight Bimetallic Catalysts

“…Recently, Mizuno and co-workers reported the synthesis of (Bu 4 N) 4 [γ-SiW 10 O 34 (H 2 O) 2 ] (4, Figure 3), which displays remarkable regioselectivity in olefin epoxidation and quantitative utility of hydrogen peroxide. 18,19 The latter feature of 4 prompted us to consider its utility in the oxygenation of sulfides by H without and with imidazole resulted in the complete consumption of CEPS in 6 h (entry 1) and 2 h (entry 2), respectively, while sulfones were not detected among the products. Prevention of sulfone formation is significant in the decontamination of mustard gas since its sulfone is also highly toxic.…”