An improved catalyst architecture for rhodium(iii) catalyzed C-H activation and its application to pyridone synthesis

We have developed a method for preparing pyridones from the coupling reaction of acrylamides and alkynes with either stoichometric Cu(OAc) ₂ or catalytic Cu(OAc)₂ and air as oxidants. In the course of these studies, it was found that a larger ligand, 1,3-di-tert- butylcyclopentadienyl (termed Cp^t) results in higher degrees of regioselectivity in the alkyne insertion event. The transformation tolerates a broad variety of alkynes and acrylamides. Furthermore, Cp^t and Cp* demonstrate similar catalytic activity. This similarity allows for mechanistic studies to be undertaken which suggest a difference in mechanism between this reaction and the previously studied benzamide system.