N-Heterocyclic Carbene-Catalyzed Atroposelective Synthesis of Pyrrolo[3,4-b]pyridines with Configurationally Stable C–N Axial Chirality

Abstract

The first atroposelective synthesis of pyrrolo­[3,4-b]­pyridines catalyzed by N-heterocyclic carbene has been achieved. A wide range of chiral atropisomers of pyrrolo­[3,4-b]­pyridines were obtained in high yields with excellent enantioselectivities (96–99% enantiomeric excess). The experimental results and density functional theory calculations showed that the C–N axial chirality of the product had high thermal stability.

N‐Heterocyclic carbene‐catalyzed Atroposelective Annulation for Access to Pyrrolo[3,4‐b]pyridines Derivatives with C−N Axial Chirality

“…α ‐Aminomaleimides were proved could be used as an excellent nucleophile in various nucleophilic addition reactions [8] . However, the similar work was reported by Hui's group [9] . Compared with the reported work, this research tolerated different reaction conditions that largely reduced the amount of enals.…”

“…[8] However, the similar work was reported by Hui's group. [9] Compared with the reported work, this research tolerated different reaction conditions that largely reduced the amount of enals. Thiourea additive was found to facilitate the reaction with an appreciable improvement on the reaction yield.…”

Oxidative N‐Heterocyclic Carbene Catalysis

“…Oxidative NHC‐catalysis proved to be a winning ticket for atroposelective synthesis of pyrrolo[3,4‐ b ]pyridines by Michael/lactamization reaction of enals with 3‐arylamino‐substituted maleimides. [85] When these two components were placed in presence of chiral aminoindanol‐derived triazolium pre‐catalyst (15 mol%), DBU (1.5 equiv. ), and DQ (2.0 equiv.…”

Visible light-promoted intermolecular cyclization/aromatization of chalcones and 2-mercaptobenzimidazolesviaan EDA complex and a mechanism study

“…At present, the cascade reaction has been considered as one of the most important methods for the construction of heterocyclic compounds. 9 Among them, the development of a mild and efficient synthesis method of imidazo[2,1- b ]thiazoles has always been a research focus in organic synthetic chemistry, because of their important role in many fields. In 1988, Chimirri 10 first summarized the research progress of imidazo[2,1- b ]thiazole, mainly focusing on its preparation methods.…”