Metal-free cross-dehydrogenative coupling of benzimidazoles with aldehydes to N-acylbenzimidazoles

Synthesis of Phthalides and α,β-butenolides by Transition Metal-Catalyzed Activation of C—H Bonds

“…Estrone-containing acrylate can also be coupled with benzamide ( 59 ). The main drawback of this methodology is that benzoyl benzimidazole is not commercially available and needs to be prepared; however, it can be obtained in a single step by dehydrogenative coupling of benzaldehyde and benzimidazole without the use of transition metals ( Scheme 31 ) [ 37 , 38 ]. The annulative coupling likely consists of four tandem reactions ( Scheme 32 ): (a) an olefination, in which benzimidazole acts as a directing group; (b) an acetylation, in which benzimidazole acts as a leaving group and is replaced by acetate; (c) acetate hydrolysis with liberation of the COOH group; and (d) cyclization.…”

Cross Dehydrogenative Coupling (CDC) Reactions of N,N‐Disubstituted Formamides, Benzaldehydes and Cycloalkanes

“…Cross dehydrogenative coupling between aryl aldehydes and benzimidazole derivatives for C–N bond formation was introduced by Wang et al (Scheme ) . By using 2 equiv.…”

Nitroxide‐Catalyzed Oxidative Amidation of Aldehydes to Yield N‐Acyl Azoles Using Sodium Persulfate

“…An alternative is to use an oxidative amidation approach. However, this typically requires the use of superstoichiometric quantities of peroxides and high temperatures [19,20] . Our group [21] and others [22,23] have successfully implemented a methodology for oxidative amidation of aldehydes using 4‐acetamido‐2,2,6,6‐tetramethylpiperidine‐1‐oxoammonium tetrafluoroborate (AcNH‐TEMPO + BF 4 − , 1 ) (Figure 1a).…”