The invention provides a process for preparing a compound of the formula:-
or a base salt thereof,
wherein
R² is hydrogen or C₁-C₆ alkyl optionally substituted by up to 3 substituents each independently selected from C₁-C₆ alkoxy and C₁-C₆ alkoxy(C₁-C₆ alkoxy)-; and
R³ is C₁-C₆ alkyl or benzyl, said benzyl group being optionally ring-substituted by up to 2 nitro or C₁-C₄ alkoxy substituents,
comprising reaction of a compound of the formula:-
wherein
R¹ is C₁-C₄ alkyl, phenyl, benzyl or C₁-C₄ alkoxy; and
R² and R³ are as previously defined for a compound of the formula (I), with hydrogen peroxide or a source of peroxide ions: said process being optionally followed by conversion of the compound of the formula (I) to a base salt thereof.
本发明提供了一种制备如下式化合物的工艺
或其碱盐、
其中
R² 是氢或任选被最多 3 个各自独立选自 C₁-C₆ 烷氧基和 C₁-C₆ 烷氧基(C₁-C₆ 烷氧基)- 的取代基取代的 C₁-C₆ 烷基;和
R³ 是 C₁-C₆烷基或苄基,所述苄基可任选被最多 2 个硝基或 C₁-C₄ 烷氧基取代基环取代、
包括反应式如下的化合物
其中
R¹ 是 C₁-C₄ 烷基、苯基、苄基或 C₁-C₄ 烷氧基;以及
R² 和 R³ 如前定义的式 (I) 化合物,
过氧化氢或过氧化物离子源:上述过程之后可选择将式 (I) 化合物转化为其碱盐。