An Improved Synthetic Route for Preparative Process of Vardenafil

A new, convergent synthetic route for the process optimization of vardenafil (Levitra), a potent and effective PDE5 inhibitor, is described. Key improved steps in the preparative process are that the chlorosulfonation reaction is at the beginning and the dehydration-cyclisation reaction is at a later stage so that the synthetic route has a better overall yield and simpler workup operations. The yield of vardenafil produced from this synthetic route is around 45% over seven steps with purity at 99.2% (HPLC).