TCT‐Mediated Process for the Preparation of Nafamostat Mesylate and Camostat Mesylate.

The present work describes the s‐trichlorotriazine (TCT)‐mediated formation of highly functionalized ester‐based drugs, namely nafamostat mesylate and camostat mesylate. The TCT‐mediated activation of acids followed by the attack of a hydroxyl group (−OH group) resulted in the formation of ester. The high aqueous solubility of cyanuric acid eases the work‐up process and avoids repetitive washing process (better E‐factor). The present method also avoids using pyridine as a base, and instead of that, N‐methylmorpholine (NMM) was used for the coupling. Moreover, we have also demonstrated the synthesis of key intermediates namely, 4‐guanidinobenzoic acid and 6‐hydroxy‐2‐naphthimidamide from economical and readily available raw materials. The TCT‐mediated coupling provides many advantages in scalability, cost‐effectiveness and environmental friendly handling. [ABSTRACT FROM AUTHOR]