Synthesis of new 8-arylisoquinoline derivatives by application of palladium-catalyzed Suzuki cross-coupling reactions

Protecting-Group-Free Synthesis of 1-Phenylisoquinolin-4-ols: Thermal Cyclization of Methyl 2-[(Diphenylmethylidene)amino]acetates

A protecting-group-free synthetic approach to 1-phenylisoquinolin-4-ols was developed by the intramolecular thermal cyclization of methyl 2-[(diphenylmethylidene)amino]acetates. R¹ and R² substituents were found to affect the required reaction temperatures, time, and yields of the cyclized products. The reactivity of the Schiff bases increased upon introduction of α-benzoyl and α-ester groups (R²). The cyclization yield also depended on the position of the R¹ substituents on the phenyl groups.