Cobalt(II)-Catalyzed Decarboxylative C-H Activation/Annulation Cascades: Regioselective Access to Isoquinolones and Isoindolinones

A new cobalt(II)-catalyzed decarboxylative C-H activation/annulation of benzamides and alkynyl carboxylic acids has been described. Alkynyl carboxylic acids were first employed as the coupling partners using inexpensive Co(OAc)(2)center dot 4H(2)O as the catalyst. This method enables a switchable cyclization to isoquinolones and isoindolinones with excellent selectivity. Moreover, a catalytic amount of Ag2O was adopted as co-catalyst and O-2 (from air) as a terminal oxidant for the preparation of isoquinolones.