Palladium/Norbornene‐Catalyzed C−H Alkylation/Alkyne Insertion/Indole Dearomatization Domino Reaction: Assembly of Spiroindolenine‐Containing Pentacyclic Frameworks. (23rd March 2018)

• Record Type: Journal Article
• Authors: Bai, Lu; Liu, Jingjing; Hu, Wenjie; Li, Kunyu; Wang, Yaoyu; Luan, Xinjun
• Is Part Of: Angewandte Chemie. Volume 130:Number 18(2018)
• Page Start: 5245
• Page End: 5249
• Publication Date: 2018-03-23
• Subjects: C-H-Aktivierung -- Cyclisierungen -- Desaromatisierung -- Heterocyclen -- Palladium; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201801894
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Reported is a highly chemoselective intermolecular annulation of indole‐based biaryls with bromoalkyl alkynes by using palladium/norbornene (Pd/NBE) cooperative catalysis. This reaction is realized through a sequence of Catellani‐type C−H alkylation, alkyne insertion, and indole dearomatization, by forming two C(sp 2 )−C(sp 3 ) and one C(sp 2 )−C(sp 2 ) bonds in a single chemical operation, thus providing a diverse range of pentacyclic molecules, containing a spiroindolenine fragment, in good yields with excellent functional‐group tolerance. Preliminary mechanistic studies reveal that C−H bond cleavage is likely involved in the rate‐determining step, and the indole dearomatization might take place through an olefin coordination/insertion and β‐hydride elimination Heck‐type pathway.