Synthesis of 5,6‐dihydro‐8‐methoxy‐4 H ‐imidazo[4,5,1‐ ij ]quinolines and some related ring systems

Reduction of amides of 8‐amino‐6‐methoxyquinoline over platinum oxide in glacial acetic acid at room temperature affords 2‐substituted‐5,6‐dihydro‐8‐methoxy‐4 H ‐imidazo [4,5,1‐ ij ]‐quinolines (I). The method could not be utilized for urea or carbamate derivatives of 8‐amino‐6‐methoxyquinoline. 2‐Amino derivatives of I were prepared through the chloro compound obtained from 5,6‐dihydro‐8‐methoxy‐4 H ‐imidazo[4,5,1‐ ij ]quinolin‐2(1 H )‐one, (IV). Several related ring systems have also been prepared.