Construction of benzo-fused indolizines, pyrrolo[1,2-a]quinolines via alkyne-carbonyl metathesis

The strategic use of a sequential Sonogashira coupling/intramolecular alkyne-carbonyl metathesis process for the synthesis of a pyridine ring from 1-(2-haloaryl)-1H-pyrrole-2-carbaldehydes allowed ready access to diverse novel benzo-fused indolizines, pyrrolo[1,2-a]quinolines, in good to excellent yields. As a hybrid structure of indolizine and quinoline, the resulting scaffold has an acyl substituent at the C5 position, which is difficult to make by any other known approaches.