A solution of ethyl 3-(t-butylthio)-2-oxopropanoate (18.6 g), 1-(4-chlorobenzyl)-1-(4-allyloxyphenyl)hydrazine hydrochloride (26.3 g), and NaOAc (15 g) in 300 mL toluene and 150 mL HOAc was stirred at room temperature under nitrogen for 16 hours then at 70° C. for 2 hours. The mixture was cooled, poured onto H2O, extracted (3×) with EtOAc and, the organic layers then washed successively with sat'd. NaHCO3 and brine. After drying over MgSO4, the solution was filtered and evaporated, and the residue chromatographed (silica gel; hexane/EtOAc 4:1) to afford the title compound.
