Process Development of the Synthetic Route to Sulamserod Hydrochloride

Sulamserod hydrochloride is a potent 5-HT4 receptor antagonist and was a clinical candidate for the treatment of gastrointestinal disorders. Process development of the fairly long synthetic route (12 linear, 14 overall steps) was undertaken. Process improvements were highlighted by aromatic chlorination choices in making dichlorobenzodioxan 2 and acetylaminochloroketone 7, a transfer hydrogenation reducing a nitro group and simultaneous aromatic dechlorination without ketone reduction to give aminoketone 5, and use of the potential mutagenic iodosulfonamide 14 to make quaternary salt 11. The chemistry was scaled-up into pilot plant reactor vessels to produce multikilogram amounts of Sulamserod hydrochloride suitable for drug development.