Tandem Catalytic Systems Involving Hypervalent Iodine and other Co-catalysts

3 Tandem Catalytic Systems Involving Hypervalent Iodine and other Co-catalysts 

Yakura and coworkers have developed bifunctional catalysts bearing TEMPO and iodobenzene moieties (stmctures 110 and 111, Eigure 4.3), which are useful for the environmentally benign oxidation of primary alcohols to carboxylic acids. Reaction of primary alcohols with a catalytic amount of catalyst 111 in the presence of peracetic acid as the terminal oxidant under mild conditions affords the corresponding carboxylic acids in excellent yields [91]. 

Likewise, efficient recyclable bifunctional catalysts 112 and 113 (Eigure 4.3) bearing ionic liquid-supported TEMPO and iodoarene moieties have been developed and used for the environmentally benign catalytic oxidation of alcohols [92]. Compounds 112 and 113 have been tested as catalysts for the oxidation of alcohols to the corresponding carbonyl compounds using peracetic acid as a green and practical oxidant. Ion-supported catalysts 112 and 113 can be conveniently recovered from the reaction mixture and reused without any loss of catalytic activity (Section 5.5). 

Efficient and recyclable bifunctional catalysts bearing silica-supported RuCls and iodoarene moieties have been developed and used for the environmentally benign oxidation of alcohols or alkylarenes at the benzylic position. In the presence of these catalysts, the oxidation of alcohols or alkylbenzenes by Oxone as the stoichiometric oxidant affords the corresponding carbonyl compounds in high yields under mild conditions and convenient work-up. Furthermore, these Si02-supported bifunctional catalysts can be recovered by simple filtration and directly reused (Section 5.5) [100]. 

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