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Cp*Co III Catalyzed Site‐Selective CH Activation of Unsymmetrical O ‐Acyl Oximes: Synthesis of Multisubstituted Isoquinolines from Terminal and Internal Alkynes
Author(s) -
Sun Bo,
Yoshino Tatsuhiko,
Kanai Motomu,
Matsunaga Shigeki
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201507744
Subject(s) - chemistry , catalysis , selectivity , steric effects , yield (engineering) , medicinal chemistry , stereochemistry , organic chemistry , materials science , metallurgy
The synthesis of isoquinolines by site‐selective CH activation of O‐acyl oximes with a Cp*Co III catalyst is described. In the presence of this catalyst, the CH activation of various unsymmetrically substituted O‐acyl oximes selectively occurred at the sterically less hindered site, and reactions with terminal as well as internal alkynes afforded the corresponding products in up to 98 % yield. Whereas the reactions catalyzed by the Cp*Co III system proceeded with high site selectivity (15:1 to 20:1), use of the corresponding Cp*Rh III catalysts led to low selectivities and/or yields when unsymmetrical O‐acyl oximes and terminal alkynes were used. Deuterium labeling studies indicate a clear difference in the site selectivity of the CH activation step under Cp*Co III and Cp*Rh III catalysis.