A comparative study of conventional conditions versus microwave irradiation for the preparation of novel 1,2-Dihydro-2-imino-7-methyl-1,6(6H)-naphthyridin-5-ones

Article abstract of DOI:10.1002/jhet.5570370432

The synthesis of novel 1,6-naphthyridines 6 with potential activity against tuberculosis is described using the reaction sequence 2 → 4 → 6. Depending on the ring N-substitution of the 4-alkylamino-6-methyl-2(1H)-pyridones 1 and 2 the electrophilic attack of the Vilsmeier reagent gives rise to the formation of the exocyclic N-formyl derivatives 3 from 1 and the corresponding 3-carbaldehydes 4 from 2. 1,2-Dihydro-2-imino-7-methyl-1,6(6H)-naphthyridin-5-ones 6a-j are prepared by the Knoevenagel reaction of 4 with CH-acidic nitriles 5. These reactions are carried out using a comparative study of conventional conditions (room temperature or reflux) versus microwave irradiation.