Silver-Catalyzed 1,3-Acyloxy Migration/Diels-Alder Reaction of 1,9-Dien-4-yne Esters to Partially Hydrogenated Isoquinolines.

A synthetic method to prepare partially hydrogenated isoquinolines efficiently from silver-mediated [3,3]-sigmatropic rearrangement/Diels-Alder reaction of 1,9-dien-4-yne esters is described. The reactions were shown to be robust with a wide variety of substitution patterns tolerated to provide the corresponding nitrogen-containing heterocyclic products in good to excellent yields. This includes examples containing a bridgehead sp3 quaternary carbon center as well as the cycloisomerization of one substrate to give the corresponding bicyclic adduct in excellent yield at the gram scale.