To a mixed solution of (S)-benzyl 3-(4-(benzyloxy)phenyl)-2-(1,3-dioxoisoindolin-2-yloxy)propanoate (Compound XXVIII-1) 15.02 g (29.6 mmol) in tetrahydrofuran 60 ml and methanol 60 ml, hydrazine monohydrate 4.31 ml (88.8 mmol) was added and the mixture was stirred at room temperature for 1 hr. The reaction mixture was diluted with ethyl acetate 500 ml and washed with saturated sodium bicarbonate solution 200 ml, water 200 ml and brine 200 ml. The organic phase was dried over magnesium sulfate and filtered. The filtrate was concentrated in vacuo to give the title compound, which was used without further purification.
