Synthesis of the 2H-quinolizin-2-one scaffold via a stepwise acylation-intramolecular annulation strategy

A rapid entry into the 2H-quinolizin-2-one starting from 2-alkyl pyridine has been developed. Initial deprotonation of a 2-alkyl pyridine followed by acylation with a β-TMS-propyonate derivative provides acyclic precursors that after deprotection undergoes a 6-endo-trig cyclization to yield the desired 2H-quinolizin-2-one derivative. This synthetic strategy was found to be generally applicable as evidenced from the various examples in this letter.