Microwave-Assisted Palladium-Catalyzed Reductive Cyclization/Ring-Opening/Aromatization Cascade of Oxazolidines to Isoquinolines

An
efficient palladium-catalyzed reaction of N-propargyl
oxazolidines for the construction of 4-substituted isoquinolines
under microwave irradiation is developed. This transformation proceeds
through a sequential palladium-catalyzed reductive cyclization/ring-opening/aromatization
cascade via C–O and C–N bond cleavages of the oxazolidine
ring. The practical value of this method has also been explored by
conducting a millimole-scale reaction, as well as by transforming
the isoquinoline into a key intermediate for the synthesis of a lamellarin
analogue.