Transmission of polar substituent effects through the bicyclo[2.2.2]octane ring system as monitored by fluorine-19 NMR shifts: 19F NMR study of 10-substituted 9-fluorotriptycenes and 4-substituted-4'-fluorobibicyclo[2.2.2]octanes
Nucleophilic Substitution Induced by Electron Transfer at the Bridgehead of Polycyclic Alkanes: Competition between Polar and Radical Pathways
作者:William Adcock、Christopher I. Clark、Neil A. Trout
DOI:10.1021/jo001638w
日期:2001.5.1
triptycenes react predominantly by a polar mechanism initiated by the formation of a carbanion. In the case of the halo ketones (6, Y = O, X = Br and I), a mechanistic divergence of the reaction was unexpectedly encountered. Whereas the bromo ketone provides the substitution product (6, Y = O, X = SnMe(3)) in good yield (ca. 75%), apparently by a radicalpathway, the iodo ketone yields a fragmentation
Transmission of polar substituent effects through the bicyclo[2.2.2]octane ring system as monitored by fluorine-19 NMR shifts: 19F NMR study of 10-substituted 9-fluorotriptycenes and 4-substituted-4'-fluorobibicyclo[2.2.2]octanes