Divergent Pd-Catalyzed and Radical Cyclizations of Nucleophilic Cyclic Enamines Derived from Functionalized Amine and Aldehyde Fragments
作者:José M. Aurrecoechea、Carlos A. Coy、Oscar J. Patiño
DOI:10.1021/jo800619m
日期:2008.7.1
Tetrahydropyridines carrying pendant halide functionality at the enamine beta-carbon have been prepared by condensation between appropriately functionalized aldehydes and a vinylogous Mannich adduct. Those enamines display divergent behavior in radical and Heck reactions. Thus, radical addition takes place in a 5-exo-trig fashion whereas Heck couplings follow a 6-endo-trig pathway. The resulting polycyclic products are obtained with high regio- and stereoselectivity.
Development of an Intramolecular Aryne Ene Reaction and Application to the Formal Synthesis of (±)-Crinine
作者:David A. Candito、Dennis Dobrovolsky、Mark Lautens
DOI:10.1021/ja306881u
日期:2012.9.19
A general and high yielding annulation strategy for the synthesis of various carbo- and heterocycles, based on an intramolecular aryne ene reaction is described. It was found that the geometry of the olefin is crucial to the success of the reaction, with exclusive migration of the trans-allylic-H taking place. Furthermore, the electronic nature of the aryne was found to be important to the success
Formation of Spirocyclic Compounds from Heck Cyclizations Invoking Cyclic Enamides
作者:Gedu Satyanarayana、Martin E. Maier
DOI:10.1021/jo800650e
日期:2008.7.1
(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.