反应详情

The procedure of (20-2) of Example 20 was repeated except for using oxalic acid monoethylester and 0.09 g of the compound obtained in (20-1) of Example 20 instead of methoxyacetic acid, and subjecting column chromatography (eluent-chloroform:methanol=15:1) to obtain the title compound (0.04 g, 37%).