Formation of spirocyclic compounds from Heck cyclizations invoking cyclic enamides.
The palladium-mediated transformation of 3,4-dihydro-2(1H)-pyridinones 12 featuring a (2-bromophenyl)ethyl substituent in the 5-position produces spirocyclic products, imides 14 and amides 15. The formation of these products can be explained by insertion of the enamide double bond into the initial aryl-Pd bond followed by oxidation or reduction of the organopalladium intermediate. Alternatively, formation of these spiro compounds might proceed via acyliminium ion intermediates.
Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Gedu
G
Satyanarayana
Martin E
ME
Maier