Reactivity Umpolung of the CN Bond in Quinoxaline Scaffold Enabling Direct Nucleophilic Attack of Alkyl Grignard Reagents at the N‑Terminus

The reactivity umpolung of the CN bond in the quinoxaline scaffold has been successfully realized for the first time by introduction of a formyl or an acyl group adjacent to the C-position of the CN moiety. The reversed reactivity of the CN bond thus enabled direct nucleophilic attack of alkyl Grignard reagents at the N-terminus rather than the C-terminus, thereby providing an unprecedented and efficient method for the synthesis of quinoxalin-2­(1H)-one derivatives involving a tandem N-alkylation/CC bond cleavage process.