Oxorhenium species

Conditions were found under which simple inorganic oxorhenium species act as efficient olefin epoxidation catalysts. This has been achieved by simply replacing aqueous H2O2 with BTSP as an oxygen atom source in the epoxidation. Representative substrates include fairly unreactive olefins and/or progenitors of sensitive epoxides . For example, terminal olefins can be efficiently converted to epoxides (equation 40, Table 9). 

One recent publication from the group of Abu-Omar reports on a condensation reaction involving glycerol and furfural, both renewables, to produce dioxolanes, formally a dehydration reaction. Here, a cationic oxorhenium(V) oxazoline species is used as the catalyst for the formation of various 1,3-dioxalanes from furfural with diols or epoxides under mild conditions (Scheme 21). Especially interesting is the reaction of furfural with glycerol to obtain a 70 30 mixture of the corresponding 1,3-dioxolane and 1,3-dioxane in solvent-free conditions [125]. 

Cationic oxorhenium(V) oxazoline (Figure 3.23) was found to be especially reactive toward perchlorate in acetonitrile water media.73 The reaction is not pH dependent and proceeds smoothly at neutral pH. The perchlorate ion, C1C>4, was reduced all the way to the chloride ion, Cl. The reaction of oxorhenium(V) with perchlorate followed Michaelis-Menten showing saturation in [C10 ]. The apparent second-order rate constant for CIO4 is ca. 0.5L/(mols). The resulting cationic dioxorhenium(VII) species is more reactive toward OAT than MTO and can be turned over with organic sulfides quite readily (Figure 3.27). Therefore, under catalytic... 

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