Iridium‐Catalyzed Asymmetric Allylic Dearomatization by a Desymmetrization Strategy

• Published in: Angewandte Chemie International Edition Vol. 56; no. 47; pp. 15093 - 15097
• Main Authors: Wang, Ye, Zheng, Chao, You, Shu‐Li
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 20.11.2017
• Edition: International ed. in English
• Subjects: asymmetric catalysis; Catalysis; dearomatization; enantioselective synthesis; Indoles; Iridium; iridium catalysts; enantioselective synthesis; indoles; asymmetric catalysis; iridium catalysts; dearomatization
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201708419

A desymmetrization strategy was developed involving iridium‐catalyzed allylic dearomatization of indoles. The six‐membered‐ring spiroindolenines contain three contiguous stereogenic centers, including an all‐carbon quaternary center, and were obtained in up to 99 % yield with 99 % ee and >95:5 d.r. When treated with a catalytic amount of tosylic acid, six‐membered spiroindolenine undergoes an unprecedented six‐to‐seven‐membered ring expansion, affording the corresponding hexahydroazepino[4,5‐b]indole. The Legend of Spiro: An iridium‐catalyzed desymmetrization reaction involving allylic dearomatization of indoles was developed. The six‐membered‐ring spiroindolenines were obtained in up to 99 % yield with 99 % ee and >95:5 d.r. When treated with a catalytic amount of tosylic acid, six‐membered spiroindolenine undergoes six‐to‐seven‐membered ring expansion, yielding hexahydroazepino[4,5‐b]indole.