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An Asymmetric Pathway to Dendrobine by a Transition‐Metal‐Catalyzed Cascade Process
Author(s) -
Lee Yujin,
Rochette Elise M.,
Kim Junyong,
Chen David Y.K.
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201705713
Subject(s) - chemistry , cycloisomerization , pyrrolidine , enyne , intramolecular force , aldol condensation , allylic rearrangement , cascade reaction , catalysis , transmetalation , combinatorial chemistry , organic chemistry , stereochemistry
An asymmetric pathway to the caged tetracyclic pyrrolidine alkaloid, dendrobine, is reported. The successful synthetic strategy features a one‐pot, sequential palladium‐catalyzed enyne cycloisomerization and rhodium‐catalyzed diene‐assisted pyrrolidine formation by allylic CH activation. The developed transition‐metal‐catalyzed cascade process permits rapid access to the dendrobine core structure and circumvents the handling of labile intermediates. An intramolecular aldol condensation under carefully defined reaction conditions takes place with a concomitant detosylation, followed by reductive amine methylation, to afford a late‐stage intermediate (previously identified by several prior dendrobine syntheses) in only 10 synthetic steps overall.