4-[3-(8-cyclopentyl-2,6-dioxo-1-propyl-7H-purin-3-yl)propylcarbamoyl]benzenesulfonyl fluoride 4-[[3-(8-cyclopentyl-2,6-dioxo-1-propyl-7H-purin-3-yl)propylamino]-oxomethyl]benzenesulfonyl fluoride 4-[3-(8-cyclopentyl-2,6-diketo-1-propyl-7H-purin-3-yl)propylcarbamoyl]benzenesulfonyl fluoride