相转移催化下4-氯苯磺酰基乙酸异丙酯的烷基化反应

在有机合成中可用芳磺酰基作暂时性活化基团。芳磺酰基乙酸酯是具有活性亚甲基的弱酸性化合物。通常要在氢化钠、醇钠存在下才能起烷基化反应。Ono等曾报道4-甲苯磺酰基乙酸甲酯在DBu存在下进行烷基化反应,但反应时间长。近年来,相转移催化在有机反应中的应用受到重视,然而用固液相转移催化法使芳磺酰基乙酸酯起烷基化反应还未见报道。我们在K₂CO₃/DMF体系中,用TEBA作催化剂,研究了4-氯苯磺酰基乙酸异丙酯与不同类型卤代烃所起的烷基化反应。合成了尚未见报道的一或二烷基化产物。

Alkylation of Isopropyl 4-Chlorobenzenesulfonyl Acetate Under Phase Transfer Catalysis Condition

Alkylation of isopropyl 4-chlorobenzenesulfonyl acetate (1) with alkyl halides R¹X(R¹=n-Bu, CH₂=CHCH₂, p-CiC₆H₄CH₂, C₆H₅CH₂CH₂, C₆H₅CH₂; X=Cl, Br) in the system of K₂CO₃/DMF was carried out under solid-liquid phase transfer catalysis and five α-substituted products (2_a-e) were obtained. The monoalkylated products directly reacted with active alkyl halides R²X (R²: CH₂=CHCH₂, p-ClC₆H,CH₂, C₆H;CH₂; X=Cl, Br) in one-pot to give dialkylated compounds 3_n-t. This method has the advantage of moderate reaction conditions and high yields.