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

Synthesis of cis-(8b,14a)-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones via photo cascade reaction

A concise method for the synthesis of cis-(8b,14a)-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones 2 via photo-induced 3-([1,1'-biphenyl]-2-yl)-1-(2-hydroxyethyl)pyridin-2(1H)-ones 1 was developed. Irradiation of 1 in the solution of toluene with a 313 nm UV light in the presence of HCl gave cis-(8b,14a)-9a-α-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinoli n-14-ones and cis-(8b,14a)-9a-β-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones 2 (2-α and 2-β) in good yields. The protocol simultaneously constructs dearomatized phenanthrene ring and oxindolizidinones ring by photo cascade reaction to achieve high bonding efficiency and high atomic efficiency. Additionally, the antitumor activities of 2 was evaluated and compounds 2b-α, 2b-β, 2j-β and 2 k-α showed similar or better activity compared to the cisplatin against tumor cell lines of Leukemia HL-60, lung cancer A594, liver cancer SMMC-7721 and breast cancer MDA-MB-231.

Regiodivergent Synthesis of Methylene and Methyl Ring-Fused Isoquinolinones: Base-Promoted Isomerization of N-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 Cs₂CO₃ in dimethyl sulfoxide (DMSO) at 150 °C. A probable mechanism for Cs₂CO₃-promoted olefin isomerization was proposed and examined using D-isotope labeling experiments. Finally, yuanamide, a 13-methyl-8-oxoprotoberberine alkaloid, was synthesized using the palladium-catalyzed aza-Wacker/Heck/migration sequence.