Synthesis of labelled N‐(4‐hydroxy‐[14C(U)]phenyl)‐2‐[2,3‐dihydro‐3‐oxo‐l,2‐benzisothiazol‐2‐yl‐1,1‐dioxide]acetamide

The amidation of 2‐[1,1‐dioxide‐3‐oxo‐1,2‐benzisothiazole‐2(3H)‐yl] acetyl chloride with carbon‐14‐labelled 4‐amino‐[¹⁴C(U)]phenol in NaOAc‐HOAc buffer solution at ?10°C gave N‐(4‐hydroxy‐[¹⁴C(U)]phenyl)‐2‐[2,3‐dihydro‐3‐oxo‐1,2‐benziso‐thiazol‐2‐yl‐1,1‐dioxide]acetamide in 82% yield. Subsequent hydrolysis with aqueous 0.5 N NaOH solution afforded the ring opened product N‐(4‐hydroxy‐[¹⁴C(U)]‐phenyl)‐2‐[2‐carboxy‐phenylsulfonamido]acetamide in 80% yield. Copyright © 2005 John Wiley & Sons, Ltd.