Stereocontrolled synthesis of polysubstituted piperidines from vinylogous Mannich adducts and aldehydes
作者:José M. Aurrecoechea、Rubén Suero
DOI:10.1016/j.tetlet.2005.05.097
日期:2005.7
the Mannich-type reaction between 2-silyloxyfurans and acyliminiumions, with an α-unsubstituted aliphatic aldehyde leads to substituted 1,2,3,4-tetrahydropyridines in a process involving an enamine conjugate addition. Reduction of the tetrahydropyridine doublebond then affords 3,4,5-tri- or 3,4,5,6-tetra-substituted piperidines stereoselectively.
Catalytically generated N-methyleneamine equivalents from N-methoxymethylanilines, 1,3,5-triphenyl- and 1,3,5-tribenzylhexahydro-1,3,5-triazines in the presence of Lewis acid reacted with 2-trimethylsilyloxyfuran to give 5-aminomethyl-2,5-dihydrofuran-2-ones in high yield.
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.