Synthesis of naphthyridin-2(1H)-one derivatives via ring expansion of 3-substituted-1H-pyrrolo[2,3-b]pyridin-2(3H)-one derivatives.

The reaction of 3-substituted 1H-pyrrolo[2,3-b]pyridin-2(3H)-one derivatives with sodium azide or azidotrimethylsilane under microwave irradiation provided 3- and 4-amino-naphthyridin-2(1H)-one derivatives through cycloaddition-ring expansion. The insertion of the azide into the α,β unsaturated carbonyl of 3-substituted pyrrolo[2,3-b]pyridin-2(3H)-one derivatives proceeded via an unusual rearrangement. This methodology provided 39 ring expansion examples in moderate to good yields.