Catalytic Cycles Involving Iodide Anion or Elemental Iodine as Pre-catalysts

4 Catalytic Cycles Involving Iodide Anion or Elemental Iodine as Pre-catalysts 

Catalytic reactions, utilizing iodide anion or elemental iodine as the pre-catalysts, may involve the iodine cation, hypoiodic acid, or inorganic hypervalent iodine(III) species as active oxidants. Numerous examples of such reactions have been reported since 2010 however, no systematic mechanistic studies have been published. The oxidative catalytic reactions utilizing iodide anion or elemental iodine as a catalyst or precatalyst have been summarized in several reviews [15,101,102]. 

The same BU4NI/TBHP catalytic system has also been applied towards the a-oxyacylation of ethers with carboxylic acids in ethyl acetate at 80 °C [105], which possibly occurs via a radical mechanism. 

In the later works by Li, Xue and coworkers, the Ishihara s hypoiodite-catalytic cycloetherification has been employed for the synthesis of bis-benzannelated spiro[5.5]ketals [107] and as a key step in a new synthesis of 7-rubromycin [108]. 

Ar = Ph, 4-MeC6H4,4-CIC6H4,4-Pr CgH4, 2-MeOC6H4, 3-NO2C6H4, 2-thienyl, etc. Ar = Ph, 4-MeC6H4,4-BrCeH4 

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