4-[2-(2,6-dioxo-1,3-dipropyl-7H-purin-8-yl)ethylcarbamoyl]benzenesulfonyl fluoride 4-[[2-(2,6-dioxo-1,3-dipropyl-7H-purin-8-yl)ethylamino]-oxomethyl]benzenesulfonyl fluoride 4-[2-(2,6-diketo-1,3-dipropyl-7H-purin-8-yl)ethylcarbamoyl]benzenesulfonyl fluoride