Synthesis of 2-Substituted Quinolines from 2-Aminostyryl Ketones Using Iodide as a Catalyst.

A new protocol for the synthesis of 2-substituted quinolines from 2-aminostyryl ketones has been developed using iodide as a nucleophilic catalyst. Conjugate addition of iodide to 2-aminostyryl ketones yielded the corresponding β-iodoketones, which could have a conformation where the amino and carbonyl groups are proximal through free rotation about the Cα-Cβ single bond. Subsequent condensation between the amino and carbonyl groups followed by elimination of hydrogen iodide provided the corresponding quinolines, with regeneration of the iodide catalyst.