Palladium(0)-catalyzed alkynyl and allenyl iminium ion cyclizations leading to 1,4-disubstituted 1,2,3,6-tetrahydropyridines

Abstract

(Chemical Equation Presented) The biologically important title heterocyclic compounds can be synthesized by two methods based on the cyclization of alkynyl and allenyl iminium ions generated in situ in the presence of organometallic reagents (see scheme). Symmetrical and unsymmetrical tetrahydropyridines with diverse substituents R4 were prepared in a single step under mild conditions. R1 = n-, sec-, tert-alkyl; R4 = aryl, 1-alkenyl, alkyl, 1-alkynyl, B(pinacolato). © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.