反应详情

Precursors of Example 28 starting from 4-chloro-3-methylsulfonylbenzoic acid via 4-N-hydrazino-3-methylsulfonylbenzoic acid (m.p. 243°-245° C.) and its hydrogenolytic N--N cleavage with Raney nickel catalyst in methanol/aq. NH3 under normal pressure at room temperature to give 4-amino-3-methylsulfonylbenzoic acid (m.p. 258°-262° C.) and subsequent reaction with thionyl chloride and methanol to give methyl 4-amino-3-methylsulfonylbenzoate (m.p. 146° C.).