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Palladium/Norbornene‐Catalyzed C−H Alkylation/Alkyne Insertion/Indole Dearomatization Domino Reaction: Assembly of Spiroindolenine‐Containing Pentacyclic Frameworks
Author(s) -
Bai Lu,
Liu Jingjing,
Hu Wenjie,
Li Kunyu,
Wang Yaoyu,
Luan Xinjun
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201801894
Subject(s) - indole test , chemistry , alkyne , norbornene , migratory insertion , insertion reaction , alkylation , palladium , annulation , olefin fiber , combinatorial chemistry , catalysis , stereochemistry , medicinal chemistry , organic chemistry , polymer , monomer
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.