Ring Expansion of 2‑Azido-2-phenyl-indan-1,3-dione for the Generation of Heterocyclic Scaffolds

A novel ring expansion based on the
readily available 2-azido-2-phenyl-indan-1,3-dione
is described. Treatment with primary amines and cesium carbonate in
a two-step sequence gives rise to 3-amino-2,3-dihydroisoquinoline-1,4-diones
with an unprecedented substitution pattern. The corresponding conversion
using amino acid methyl esters leads directly to a novel tricyclic
1,10a-dihydroimidazo-isoquinoline-2,5,10-trione scaffold, a structure
that has never been reported before, to the best of our knowledge.