(i) Ethyl bromoacetate, NaH, DMF; then, hydrazine hydrate (80%), ethanol, reflux, 24 h; (ii) sulfonyl chloride, Et3N, THF, rt, 18 h; (iii) -Ph (or p-Cl-Ph) isothiocyanate, ethanol, reflux, 3 h; (iv) Ethyl bromoacetate, sodium acetate, ethanol, reflux, 3 h; (v) CDI, DMF, rt, 1d. (vi) 4-Fluorobenzoyl chloride, Et3N, DMF, 4 h