An Intramolecular C(sp²)–H Amidation Using N‐Iodosuccinimide

Abstract

An N‐iodosuccinimide (NIS) mediated intramolecular dehydrogenative C(sp2)–H amidation is reported for easy and convenient access to 1,2‐disubstituted benzimidazoles. The nonprefunctionalized C(sp2)–H and N(sp3)–H bonds were directly coupled using NIS in trifluoroethanol, which proved to be mild alternative to strong oxidative iodine(III) reagents. The reaction worked at room temperature, under an air atmosphere, and in the absence of any base additive.

Crystal structures of arylsulfonylation products of 2-alkyl-5-substituted-1H-benzimidazoles

“…The synthesis of arylsulfonylbenzimidazoles has therefore attracted the attention of organic chemists. The preparation of an individual substance of this class involves the aryl-sulfonylation of benzimidazole (Abdireimov et al, 2010), either by an intramolecular Csp 2 -H amidation using Niodosuccinimide (Alam et al, 2018), the rearrangement of 7-sulfonamidobenzoxazole with ZnCl 2 or Zn(NO 3 ) 2 (Tanakit et al, 2012), or the intramolecular amidation of N-tosyl-ophenylenediamine derivatives (for obtaining 1,2-disubstituted benzimidazoles) (Maiti & Mal, 2015;Hu et al, 2017). The above reactions produce a variety of arylsulfonylbenzimidazole derivatives but there are other conditions that produce two derivatives such as the amination of N 00 -aryl-N 0tosyl/N 0 -methylsulfonylamidines derivatives (Alla et al, 2013).…”