Chemistry of trivalent iodine:part II mechanism of action of phenyliodoso acetate on p-substituted acetanilides and N-alkylanilines

Metal‐Free Oxidative Carbon‐Heteroatom Bond Formation Through C–H Bond Functionalization

“…Unlike Kikugawa's hydroxylation [Scheme , Equation (1)], this modified method [Scheme , Equation (2)] also allowed the direct construction of C–O bonds in electron‐poor aryl anilides. Moreover, when the para ‐position of the arene was blocked by a substituent, the C–O bond was formed at the meta ‐position, consistently with the observation of Nair's group 63. Mechanistically, in all cases similar electrophilic substitution pathways, consisting of generation of a nitrenium cation by the reaction between the amide and PIFA, followed by trapping with nucleophilic oxygen on the charge‐delocalized arene, might be operative.…”

Nitrenium Ions from Amine‐Iodine(III) Combinations

“…A decade after Nair's discovery, Kikugawa and co‐workers in 1990 reported the generation of N ‐acylnitrenium ion 17 from N ‐methoxy amide 16 by treatment with oxidant PhI(OCOCF 3 ) 2 or PIFA which represents the opening of modern organic synthesis using nitrenium ions under iodine(III) chemistry . The electrophilic nitrenium ion was trapped in an intermolecular way by nucleophilic attack from either benzene or anisole (Figure ).…”

“…From a mechanistic standpoint, the generation of a nitrenium ion using an iodine(III) oxidant is believed to start by ligand exchange at the iodine center of the oxidant with amine 7 to form amido‐λ 3 ‐iodane ( 8 , Figure ) . Heterolysis of the nitrogen−iodine bond leads to reductive elimination of monovalent iodoarene and generation of nitrenium ion 2 . Being electrophilic in nature, nitrenium ions are highly susceptible to nucleophilic attack.…”

Phenyliodine Bis(trifluoroacetate) Mediated Intramolecular Oxidative Coupling of Electron-Rich N-Phenyl Benzamides

“…Compound 1k and 1l were transformed smoothly to 2k and 2l too in good yields ( Table 2, entries 10 and 11). However, the expected reaction failed to take place for compounds 1m-p ( Table 2, entries [11][12][13][14].…”

“…In an early study, Barlin and Riggs found that acetanilides having electron-donating substituents at the para position reacted with PIDA to afford meta-acetoxy-substituted products in high yields. 11 The reaction was later demonstrated to proceed via an ionic pathway by Nair et al 12 Recently, Gu reported that the reaction between anilides and PIFA led to the direct para acetoxylation and etherification of anilides. 13 Kikugawa et al investigated the reaction between N-arylamides and PIFA, and found that the composition of the products depended on the electronic nature of anilides and reaction conditions.…”