1-(4-Azidomethyl-1,3-thiazol-2-yl)-3-t-butyldiphenylsilyloxyazetidine (1.06 g, 2.37 mmol) (obtained as described in Reference Example 62(1)) in methanol (53 ml) was subjected to catalytic hydrogenation in the presence of 20% palladium hydroxide on charcoal (1.05 g) at room temperature. After checking the completion of the reaction, the reaction mixture was filtered in order to remove the catalyst and the filtrate concentrated under reduced pressure. The residue was dissolved in methylene chloride (53.2 ml). To the mixture were added p-nitrobenzyl chloroformate (0.76 g, 3.52 mmol) and triethylamine (0.5 ml, 3.59 mmol) in an ice bath, and the mixture was stirred at room temperature overnight. After checking the completion of the reaction, the mixture was distilled under reduced pressure. The residue was partitioned between ethyl acetate and saturated aqueous sodium hydrogencarbonate solution. The organic layer was washed with saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by chromatography on a silica gel column using toluene:ethyl acetate (3:2) as the eluant to afford 3-t-butyldiphenylsilyloxy-1-[4-(p-nitrobenzyloxycarbonylaminomethyl)-1,3-thiazol-2-yl]azetidine (867.2 mg, yield 61%) as a yellow solid.
