A Facile, Improved Synthesis of Sildenafil and Its Analogues

Abstract

This paper describes the facile synthesis of sildenafil citrate (<b>1</b>) and its related compounds through an improved chlorosulfonation reaction using chlorosulfonic acid and thionyl chloride. This synthesis results in pure sildenafil with high yield. The structures of the compounds were determined with infrared (IR), ¹H-NMR and ¹³C-NMR spectroscopic methods, and high resolution mass spectroscopy (HRMS) analysis.