One-pot synthesis of dihydroquinolones by sequential reactions of o -aminobenzyl alcohol derivatives with Meldrum's acids.

The functionalized 3,4-dihydroquinolin-2-one nucleus has been assembled in good to high yields through the sequential reaction of readily available N -Ts- o -aminobenzyl alcohols with 5-substituted Meldrum's acid derivatives under mild basic conditions. Highly diastereoselective synthesis of 3-substituted-4-phenyl-1-tosyl-3,4-dihydroquinolin-2(1 H )-ones was accomplished from N -(2-(hydroxy(phenyl)methyl)phenyl)-4-methylbenzenesulfonamide under the same reaction conditions. Regarding the reaction mechanism, we hypothesized that the formation of dihydroquinolones proceeds through the in situ generation of aza- o -QMs followed by conjugate addition of enolate/cyclization/elimination of acetone and CO 2 .