Efficient Synthesis of New Polyfunctionalized Thia-Diazaacenaphthylenes From Imidazo[1,2-a]Pyridines

摘要

New heterocycles containing sulfur and nitrogen with an azaindolizine moiety were synthesized. The imidazo[1,2-a]pyridine-2,5-dicarboxylates (9a, b, 10a, b) and 5-formuylimidazo[1,2-a]pyridine-2-carboxylates (17a, b) treated with ethyl thioglycolate and lithium hydroxide underwent ring closure yielding the multifunctional[2,3,3]cyclazines (13) and (18). Under similar conditions, the imidazo[1,2-a]pyridinecarbaldehydes (22a, b) and (29a, b) were converted into the linearly cyclized compounds thieno[3,2-b]imidazo[1,2-a]pyridines (23, 31) and a peri annulated product thiadiazaacenaphthylene (30).