Transition Metal‐Catalysed Direct C−H Bond Functionalizations of 2‐Pyridone Beyond C3‐Selectivity

Abstract

Abstract2‐Pyridone is a ubiquitous motif in natural products, drug molecules, ligands in catalysis and organic materials. There is a necessity of direct step‐economic methods for the construction of 2‐pyridone based molecules. Strategically, the primary developments have led to the C3‐functionalizations due to the inherent reactivity of this center. Despite this, many elegant transition metal‐catalysed methods have been established to introduce versatile functional groups at the C4, C5 and C6‐position via direct C−H bond functionalizations. This minireview focuses on the categorized introduction of different functional groups at the 2‐pyridone scaffolds beyond C3‐selectivity and discusses substrate scope, limitations and plausible mechanistic details.

Pd(II)-Catalyzed Oxidative Naphthylation of 2-Pyridone through N–H/C–H Activation Using Diarylacetylene as an Uncommon Arylating Agent

“…Classical methods to access these scaffolds often require multistep synthetic procedures, and generally they are manipulated for a fixed target. Therefore, steady progress has been observed in the direct step-economic modifications of 2-pyridone and related scaffolds . In the search for promising structurally diverse 2-pyridone scaffolds, an internal alkyne was considered as a useful coupling component in the direct C–H bond functionalizations of 2-pyridone scaffolds .…”

Base‐Promoted Synthesis of 3‐Alkenyl‐2‐pyridones from N‐Propargyl‐β‐enaminones and Aryl Aldehydes

“…[ 4 ] They are also wildly used as important building blocks in organic synthesis. [ 5 ] Thus, the preparation of pyridone derivatives has attracted great interest.…”

Ligand-Controlled Ni(0)–Al(III) Bimetal-Catalyzed C3–H Alkenylation of 2-Pyridones by Reversing Conventional Selectivity

“…A large number of natural products and bioactive molecules are composed of 2-pyridone, and the development of selective C–H functionalization for construction of multiple substituted 2-pyridone derivatives has gained considerable interest during the past decades . Owing to the difference of electron density of four C–H bonds on the ring, for example, electron-deficient C4 and C6–H bonds and electron-rich C3 and C5–H bonds (Scheme a), a diverse range of selective C–H functionalization reactions have been achieved. − Nevertheless, C3–H alkenylation of simple 2-pyridones without predecorations still remains an elusive challenge .…”