申请人:DOWELANCO
公开号:EP0441457A2
公开(公告)日:1991-08-14
Larger (C₆-C₁₂) esters of substituted 2-pyridinyloxyalkanoic acids, such as 1-methylheptyl (4-amino-3,5-dichloro-6-fluoro-2-pyridinyloxy)acetate, are prepared in high yield and purity by first preparing the methyl or ethyl ester and then transesterifying with a C₆-C₁₂ alcohol. The methyl or ethyl ester can be prepared by alkylation of an alkali metal salt of 4-amino-3,5-dichloro-6-fluoro-2-pyridinol with methyl or ethyl chloroacetate and the transesterification can be carried out in the presence of a tetraalkyl titanate catalyst.
首先制备甲基或乙基酯,然后与 C₆-C₁₂醇进行酯交换反应,可以高产率和高纯度制备取代的 2-吡啶基烷酸的较大(C₆-C₁₂)酯,如 1-甲基庚基(4-氨基-3,5-二氯-6-氟-2-吡啶氧基)乙酸酯。甲酯或乙酯可通过 4-氨基-3,5-二氯-6-氟-2-吡啶醇的碱金属盐与氯乙酸甲酯或乙酯的烷基化反应制备,然后在四烷基钛酸酯催化剂存在下进行酯交换反应。