Regioselective palladium-catalyzed tandem .alpha.-arylation/isomerization of cyclic enamides

Palladium-catalyzed reactions of aryl iodides with the cyclic enamides 1-(methoxycarbonyl-1,4,5,6-tetrahydropyridine (1), 1-formyl-1,4,5,6-tetrahydropyridine (2), and 1-formyl-2-pyrroline (3) result in regioselective α-arylation, with concomitant isomerization of the double bond into conjugation with the nitrogen atom. The new enamides 1-(methoxycarbonyl)-2-aryl-1,2,3,4-tetrahydropyridines (4), 1-formyl-2-aryl-1,2,3,4-tetrahydropyridines (5), and 1-formyl-5-phenyl-2-pyrroline (6a) were isolated