Herein, we report a C–N coupling reaction via antiaromatic endocyclic nitrenium ions. The nitrenium ion intermediate was generated by a combination of iodine­(III) reagent PhI­(OCOCF3)2 and the N–H center of benzimidazole units at ambient laboratory conditions. Metal-free synthesis of benzimidazole-fused phenanthridine derivatives was achieved in good to excellent yields.

Hypervalent iodine compounds are known for their extensive use as potentialo xidants in organic synthesis.I ns pite of the similar reactivity with transitionm etals,h ypervalent iodine reagents are more preferred because of their environmental sustainability.A mong several types of hypervalent iodine reagents,t rivalent organoiodine(III) reagents are highly popular due to their easy accessibility,s tability and controlled oxidizing reactivity.A lso, iodine(III) reagents are commerciallya vailable andi nexpensive. Amines and amidesr eact with iodine(III) oxidants in some specificw ay to provide ad ivalent electrophilic ionic species known as an itrenium ion. Depending on the nature and stability of the nitrenium ion, numerous oxidative transformations to generate valuable functional molecules have been reported.T his review encompassesd iscussionsa bout hypervalent organo iodine(III)-enabled organic transformationsw ith the involvemento fanitrenium ion as an intermediate. Figure1.Ionic electrophilic speciesw ith 6v alance electrons.

Phenyliodinetrifluoroacetate (PIFA)-mediated dehydrogenative CÀHe therification of anilides is reported for the synthesis of -OCH 2 CF 3 and -OCD 3 incorporated aryl ethers. Nucleophilicity of the added nucleophiles and soft-hard acid-base (SHAB) principle were rationalized to understandt hose reactions. Anilides and PIFAl ed to the electrophiles either softer nitrenium ions or harder carbenium ions. The harder nucleophile alcohols exclusively reacted with the carbenium ions to produce aryl ethers.

Performing any synthesis using several arylamines and hypervalent iodine(V) reagents by direct mixing is unrealistic because of the high exothermic reaction or explosion. Herein we demonstrate, when anilines were substituted with an amide group at the ortho-position, successful chemical reactions could be performed due to intramolecular control. At maximum contact of the reacting substances, i.e., under solvent-free mechanochemical conditions, 2-aminobenzamides, aryl-, alkylaldehydes and the iodine(V) reagent o-iodoxybenzoic acid (IBX) led to substituted quinazolin-4(3H)-one derivatives in fair yields.

No abstract