Photoinduced cobalt catalyzed site selective alkylation of 2-pyridones

Abstract

Herein, a selective C3- and C6-alkylation reaction of 2-pyridone by a direct C–H functionalization approach was used to access 2-pyridone derivatives. Under photocatalytic reaction conditions, alkyl halides or methanesulfonates were used as alkyl radical sources utilizing cobalt catalyzed reductive cleavage. The formation of carbon–carbon bonds exhibited site-selectivity at either the C3 or C6 position of 2-pyridone, leading to the generation of the desired products in yields ranging from moderate to excellent. Additionally, this methodology facilitated expedited access to C3-alkylated and 1,6-annulated 2-pyridone compounds, thereby offering potential utility in the synthesis of the small molecules (+)-julandine and (+)-cryptopleurine.