Facile Synthesis of Pyrrolyl 4‑Quinolinone Alkaloid Quinolactacide by 9‑AJ-Catalyzed Tandem Acyl Transfer–Cyclization of o‑Alkynoylaniline Derivatives

The synthesis of pyrrolyl 4-quinolinone alkaloid, quinolactacide, and its analogues was successfully achieved using 9-azajulolidine (9-AJ)-catalyzed tandem acyl transfer–regioselective cyclization of N,N-diacyl-o-alkynoylaniline derivatives. In addition, this organocatalytic reaction was successfully utilized for the synthesis of a variety of 3-acyl-4-quinolinones in moderate-to-good yields. Mechanistic studies, including a time course nuclear magnetic resonance (NMR) experiment, indicated that the 1,4-addition of 9-AJ to an ynone system can be considered to be the rate-determining step in this quinolinone synthesis.