Enantioselective Syntheses of Tricyclic Benzimidazoles via Intramolecular Allylic Aminations with Chiral-Bridged Biphenyl Phosphoramidite Ligands

• Published in: Organic letters Vol. 21; no. 3; pp. 608 - 613
• Main Authors: Jiang, Xiaoding, Chen, Xiangmeng, Li, Yongsu, Liang, Hao, Zhang, Yaqi, He, Xiaobo, Chen, Bin, Kwok Chan, Wesley Ting, Chan, Albert S. C, Qiu, Liqin
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.02.2019; Amer Chemical Soc
• Subjects: amination; benzimidazoles; carbon; carbonates; catalytic activity; chemical structure; Chemistry; Chemistry, Organic; enantioselectivity; ligands; Physical Sciences; Science & Technology; ATROPISOMERIC MONOPHOSPHINE LIGANDS; SUBSTITUTION; POLYMERASE-1 PARP-1 INHIBITORS; DIPHOSPHINE LIGANDS; CATALYZED HYDROGENATION; IRIDIUM; BIOLOGICAL EVALUATION; FUSED PIPERAZINE; ALPHA-ALLYLATION; ASYMMETRIC HYDROGENATION
• ISSN: 1523-7060; 1523-7052; 1523-7052
• DOI: 10.1021/acs.orglett.8b03640

The first iridium-catalyzed enantioselective intramolecular allylic aminations of benzimidazole-tethered allylic carbonates were developed, providing three classes of tricyclic benzimidazoles bearing a tertiary carbon stereogenic center in high yields and excellent enantioselectivities (up to 99% yield, 99% ee). Wide substrate scope, excellent catalytic efficiency and mild conditions rendered this protocol particularly superior and practical. Impressively, the chiral bridge with a tunable structure was shown to provide a very good adjustment space for the chiral environment. The excellent catalytic performance of the ligands manifested their advantages over the bisphenol-based and BINOL-derived counterparts in these transformations. It also highlighted the potential application value of the chiral-bridged ligands.