Cascade synthesis of 3-quinolinecarboxylic ester via benzylation/ propargylation-cyclization.

Reactions of 2-amino-aryl alcohols with beta-ketoesters catalyzed by a catalytic amount of FeCl3 via tandem benzylation-cyclization produce the corresponding 3-quinolinecarboxylic esters in good to high yields. Extending this methodology to propargylation-cyclization, 2-nitrophenyl propargyl alcohols with beta-ketoesters catalyzed by FeCl3 and SnCl2 also produce the 4-alkyne-3-quinolinecarboxylic esters. The mechanistic details of this benzylation/propargylation and cyclization cascade process are also discussed.