硼酸催化酯交换法合成β-酮酸酯

以β-酮酸酯类化合物4-［2-(邻苯二甲酰亚胺基)乙氧基］乙酰乙酸乙酯为起始原料，与S-(+)-β-甲氧基-2-苯乙醇进行酯交换反应,合成了4-［2-（邻苯二甲酰亚胺基）乙氧基］-1-（2S-β-甲氧基苯乙基）丁酸酯。考察了ZnO，Zn/I₂，B(OH)₃，I₂，t-BuNH₂ 5种不同催化剂的催化效果，确定以硼酸为催化剂专一性最好。该酯交换反应最佳条件为以摩尔分数10%硼酸为催化剂，甲苯为共沸剂，两种原料物质的量比为1∶1.2，反应时间24h，反应温度140～150℃。在此条件下4-［2-（邻苯二甲酰亚胺基）乙氧基］-1-（2S-β-甲氧基苯乙基）丁酸酯的收率为33.3%。

Synthesis of β-keto ester by transesterification with boric acid as catalyst

An effcient transesterification of β-ketoesters with ethyl 4-2 2-(phthalimido)ethoxy] acetoacetate and S-( + )-13-methoxy-phenylethanol as raw materials and boric acid as catalyst is described. The boric acid is the best one among the five selected catalysts: ZnO, Zn/I_2, B(OH)_3, I_2 and t-BuNH_2. The optimal conditions for transesterification can be carried out with boric acid as catalyst under 140 - 150℃, the ratio of two compounds (ethyl 4-2 2-(phthalimido)ethoxy] acetoacetate and S-( + )-β-methoxy-phenylethanol) could be set as 1:1.2,and the reaction can be finished in 24 h, the yield is 33.3 %.