Development of an Efficient Synthesis of the Pyrrolquinolone PHA-529311

An efficient synthesis of N-(4-chlorobenzyl)-2-(2-hydroxyethyl)-8-(morpholin-4-ylmethyl)-6-oxo-6H-pyrrol[3.2.1-ij]quinoline-5-carboxamide (5) was developed. The route was chosen due to its reasonable length (seven steps), solubility of intermediates, and capabilities of the pilot and production facilities. The critical transformations in this route were the selective iodination of an aniline, formation of the quinolone, and Sonogashira coupling/pyrrole formation. In addition, removal of residual palladium and copper from the penultimate and final products, which was of lower concern during the discovery phase of development, became a difficult process chemistry issue on scale-up.