Palladium‐Catalyzed Cycloisomerization of 1,6‐Enynes Using Alkyl Iodides as Hydride Source: a Combined Experimental and Computational Study

Abstract

A palladium-catalyzed cycloisomerization of 1,6-enynes using alkyl iodides as hydride sources has been developed. The method turns undesired β-hydride elimination of alkyl iodides into a strategic advantage, efficiently giving rise to dihydropyridin-2(1H)-ones and tetrahydropyridines containing exocyclic double bonds with excellent chemo-and regio-selectivity. Experimental and computational studies support a reaction mechanism involving hydride transfer via β-hydride elimination/palladium(II) hydride migratory insertion.

Pd-Catalyzed Tandem Isomerization/Cyclization for the Synthesis of Aromatic Oxazaheterocycles and Pyrido[3,4-b]indoles

“…11 In these transformations, a B−Pd−H active species was involved as the key catalyst. To continue our interest in Pd−H catalysis, 12 we report, herein, an expedient pathway for alkene isomerization/cyclization by harnessing the versatility of B 2 X 4 reagents, which can serve as both a transition metal oxidant and as a Lewis acid for cyclization (Scheme 2b).…”