Herein, we describe the direct synthesis of quinazolinones via cross-dehydrogenative coupling between methyl arenes and anthranilamides. The C–H functionalization of the benzylic sp3 carbon is achieved by di-t-butyl peroxide under air, and the subsequent amination–aerobic oxidation process completes the annulation process. Iron catalyzed the whole reaction process and various kinds of functional groups were tolerated under the reaction conditions, providing 31 examples of 2-aryl quinazolinones using methyl arene derivatives in yields of 57–95%. The synthetic potential has been demonstrated by the additional synthesis of aryl-containing heterocycles.
29 October 2020 in The Journal of Organic Chemistry
Benzimidazoles are important N-heteroaromatic compounds with various biological activities and pharmacological applications. Herein, we present the first iron-catalyzed selective synthesis of 1,2-disubstituted benzimidazoles via acceptorless dehydrogenative coupling of primary alcohols with aromatic diamines. The tricarbonyl (η4-cyclopentadienone) iron complex catalyzed dehydrogenative cyclization, releasing water and hydrogen gas as by-products. The earth abundance and low toxicity of iron metal enable the provision of an eco-friendly and efficient catalytic method for the synthesis of benzimidazoles.