Regiodivergent Synthesis of Methylene and Methyl Ring-Fused Isoquinolinones: Base-Promoted Isomerization of -Allyl Amides.

Methylene and methyl tricyclic isoquinolinones were selectively prepared using a palladium(II)-catalyzed aerobic aza-Wacker reaction, followed by a base- and temperature-controlled Heck reaction catalyzed by palladium(0). Exo- to endo-double-bond migration in isoquinolinones was achieved with 93-99% yields by treatment of the Heck products with CsCO in dimethyl sulfoxide (DMSO) at 150 °C. A probable mechanism for CsCO-promoted olefin isomerization was proposed and examined using D-isotope labeling experiments.

Palladium-Catalyzed Stereoselective Aza-Wacker-Heck Cyclization: One-Pot Stepwise Strategy toward Tetracyclic Fused Heterocycles.

Palladium-catalyzed intramolecular tandem cyclization reactions were conducted for the synthesis of densely /fused aza-tetracyclic structures. The process involved a palladium(II)-catalyzed aerobic aza-Wacker reaction, followed by a palladium(0)-catalyzed Heck reaction. The effects of the solvent and benzene substitution pattern on the one-pot, two-step cascade reaction were studied systematically, and a probable mechanism was proposed.

One-Pot Oxidative Coupling/Decyanation of 6,7-Diphenylindolizine-5-carbonitriles and 2,3-Diphenylquinolizine-4-carbonitriles.

The one-pot oxidative coupling/decyanation reactions of 6,7-diphenylindolizine-5-carbonitriles and 2,3-diphenylquinolizine-4-carbonitriles were investigated using aryl-aryl oxidative coupling reagents. The phenanthroindolizidinones and phenanthroquinolizidinones were produced in 52-89% yields under VOF/trifluoroacetic acid or [bis(trifluoroacetoxy)iodo]benzene/BF-mediated conditions. This represents a mild and efficient approach to construct these types of pentacyclic skeletons from the corresponding cyano group-activated aza-Diels-Alder cycloadducts.