A simple catalytic synthesis of condensed pyridones from o-bromoarylcarboxamides involving ipso substitution via palladacycles

A catalytic synthesis of condensed pyridones starting from o-bromoaromatic carboxamides is reported using Pd(OAc)2/TFP as catalyst, K2CO3 as a base in DMF at 105 °C. Under these conditions an unprecedented reaction sequence occurs leading to condensed pyridones in 23-86% yield. The proposed pathway proceeds through palladacycle-catalyzed homocoupling of the bromoamide, followed by intramolecular carbon-nitrogen bond-forming reaction with the carbon atom bearing the aminocarbonyl group, which is easily eliminated under palladium catalysis. Copyright © 2006 American Chemical Society.