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Thwarting β ‐Hydride Elimination: Capture of the Alkylpalladium Intermediate of an Asymmetric Intramolecular Heck Reaction
Author(s) -
Oestreich Martin,
Dennison Philip R.,
Kodanko Jeremy J.,
Overman Larry E.
Publication year - 2001
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/1521-3773(20010417)40:8<1439::aid-anie1439>3.0.co;2-f
Subject(s) - heck reaction , chemistry , intramolecular force , oxindole , salt (chemistry) , medicinal chemistry , hydride , combinatorial chemistry , palladium , stereochemistry , organic chemistry , catalysis , hydrogen
In spite of containing three conformationally accessible β ‐H atoms , palladacycle 1 a is an isolable intermediate in the asymmetric Heck cyclization of 2 a . Although 1 a is stable in the presence of the hydrotriflate salt of 1,2,2,6,6‐pentamethylpiperidine, it is converted into the oxindole Heck product when exposed to the more acidic hydrotriflate salt of 2,6‐di‐ tert ‐butylpyridine. Heck cyclization of 2 b is also believed to proceed by way of a palladacyclic intermediate 1 b , which in this case undergoes β ‐methoxide elimination. Bn=benzyl.