To a solution of p-nitrobenzyl α-[4-cyclopropylmethoxycarbonylthio-3-phenoxyacetamido-2-oxoazetidin-1-yl]-α-[2-bromo-1-(morpholin-4-yl)ethylidene]acetate (151 mg) in methylene chloride (1.5 ml) is added aluminum chloride (0.42 mg) and the mixture is stirred for 50 minutes under ice cooling. The mixture is diluted with ice water (2 ml), stirred for 5 minutes, and stirred with a mixture (15 ml) of methanol and methylene chloride (5:1) after addition of 10% hydrochloric acid (3 ml) at room temperature for 80 minutes. The reaction mixture is diluted with ice water, and is extracted with chloroform. The extract solution is washed with water, dried over magnesium sulfate, and evaporated to give p-nitrobenzyl 3-hydroxy-7-phenoxyacetamido-3-cephem-4-carboxylate (63 mg). Yield: 63%. This product is identical with the product of Example 4.-III(3) produced by hydrolysis of the 4-morpholino group to be replaced with the corresponding hydroxy group.
