AUXILIARY SILICON IN REGIOSELECTIVE COBALT CATALIZED PROTOBERBERINE SYNTHESES

Article abstract of DOI:10.1016/S0040-4020(01)88589-6

η⁵-Cyclopentadienyl dicarbonyl cobalt catalyzes the cocyclization of 1,2-bis(propargyl)-1,2,3,4-tetrahydroisoquinolines 4b and 5 with alkynes to provide a novel synthetic entry into the tetrahydroprotoberberine nucleus.By judicious choice of trimethylsilyl substituents, regiocontrol in the D-ring can be achieved.Reaction of 4b with benzonitrile in the presence of the catalyst furnishes the rare isoquino<2,1-b>-2,6-naphthyridine framework, also regioselectively.