Cobalt-Catalyzed Carbonylative Cyclization of Pyridinyl Diazoacetates for the Synthesis of Pyridoisoquinolinones.

Dicobalt octacarbonyl-catalyzed carbonylative cyclization of pyridinyl diazoacetates is developed for the synthesis of pyridoisoquinolinones under mild conditions (room temperature) in a carbon monoxide atmosphere. Moreover, a synthetic method for various pyridoisoquinolinones from ethylpyridinyl aryl acetates is demonstrated through diazotization using TsN3 and DBU followed by Co-catalyzed carbonylation to generate ketene intermediates, which can subsequently undergo intramolecular cyclization under mild conditions in a carbon monoxide atmosphere in a semi-one-pot fashion.