Metal-free iodine-promoted oxidative

Metal-free iodine-promoted oxidative cyclization domino process was successfully utilized by Jiang et al. [15] to synthesize poly substituted oxazoles. Similarly, very efficient iodine-promoted oxidative cyclization domino process was reported by Wu et al. [16] for the synthesis of 2-acylbenzothiazoles 38 via a sp C-H functionalization (Scheme 9.8). 

The hypervalent iodine reagent PhI(OTf)2 (generated in situ) promotes the metal-free oxidative production of C-O bonds, through an intramolecular oxidative cyclization of substituted N-styrylbenzamides 131 to give oxazoles 132 (13SL2119). 

Zhao et al. utilized the remarkable oxidative property of FIFA in a C-C bond formation to prepare an array of 3-arylquinolin-2-ones 120 (Scheme 26). FIFA-promoted oxidation of N-methyl-N-phenylcinnamamides 119 in the presence of a Lewis acid afforded 3-arylquinolin-2-ones in good yields. Formation of 3-arylquinolin-2-ones was realized through the FIFA-promoted simultaneous C-C bond formation and 1,2-aryl migration. This simple and metal-free FIFA-mediated green approach for the biologically important 3-arylquinolin-2-ones also widen the synthetic utility of hypervalent iodine reagents [42]. 

A novel oxidative N-incorporation strategy for synthesis of quinoxaline diesters 72 under metal-free conditions was described by Sharada for the first time (Scheme 7.50) [119]. The hypervalent iodine(III) promoted dehydrogenative nitrogenation of A-aryl vinylogous carbamates using sodium azides as the N-source via the formation of two C( p )-N bonds leading to quinoxalines. 

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