“…((2-fluoroethyl)thio)-1,3,4-oxadiazol-2-yl)methyl 4-chlorobenzenesulfonate (4a-15). White liquid; yield, 80.5%;1 H NMR (400 MHz, CDCl 3 ) δ 7.81-7.75 (m, 2H, Ar-H), 7.50-7.45 (m, 2H, Ar-H), 5.19 (s, 2H, -CH 2 -),4.72 (t, J = 5.7 Hz, 1H, -CH-),4.60 (t, J = 5.7 Hz, 1H, -CH-),3.49 (t, J = 5.7 Hz, 1H, -CH-),3.43 (t, J = 5.7 Hz, 1H, -CH-) 13. C NMR (100 MHz, CDCl 3 ) δ 166 17,.…”