Synthesis of N-acylbenzimidazoles through [4+1] annulation of N-arylpivalimidamides with dioxazolones

In this paper, a novel and efficient synthesis of N-acylbenzimidazoles through an unprecedented [4 + 1] annulation of N-arylpivalimidamides with dioxazolones is presented. It is proposed that the formation of the title products should involve a cascade process including Rh(iii)-catalyzed C(sp(2))-H amidation of N-arylpivalimidamides using a dioxazolone as a masked amidating reagent followed by an intramolecular N-nucleophilic addition and ammonia elimination. To our knowledge, this is the first example in which N-acylbenzimidazoles were synthesized through simultaneous formation of the imidazoyl moiety and introduction of the N-acyl group. Compared with literature methods, this unique protocol has advantages such as easily obtainable substrates, redox neutral conditions, high efficiency, good atom-economy and excellent compatibility with diverse functional groups. With all these merits, it has the potential to find wide applications in related areas.

Automated summary

The novel synthesis method presented in this paper for N-acylbenzimidazoles using a [4 + 1] annulation process has advantages including easily obtainable substrates, redox neutral conditions, high efficiency, good atom-economy and excellent compatibility with diverse functional groups, showing great potential for wide applications in related areas.