Table 4. Synthesis of Tetrahydro Naphthyridones.

^aMethod A: 2 equiv of R¹CHO, 3 equiv of R²NH₂, 2% AcOH, MWI 80 °C 10 min, then NaBH₄. Method B: 2 equiv of R¹CHO, 3 equiv of R²NH₂, 5% HCO₂H, MWI 100 °C 15 min. Method C: 2 equiv of R¹CHO, 3 equiv of R²NH₂, 2% AcOH, MWI 100 °C 2.5 h, then 5% HCO₂H, MWI 100 °C 30 min.

^bIsolated as separate diastereomers.