苯并咪唑类衍生物在材料、医药、化工和农药等领域有重要价值,发展绿色简洁的方法来合成这一类化合物具有重要意义.采用机械力化学法以供-受体环丙烷二甲酯与苯并咪唑为原料,通过筛选不同的路易斯酸、液体研磨辅助剂、反应时间以及振动频率,优化得到了较佳的实验条件:三氟甲烷磺酸镱为催化剂,振动频率为 35 Hz,球磨反应时间为1.5 h.在此条件下,以42.9%～77.5%收率合成10 个β-苯并咪唑乙基丙二酸二甲酯类化合物(3a～3j),其结构经1 H NMR、HR-MS(ESI)表征.该合成方法具有反应条件温和、操作简单、无溶剂且底物拓展性好等优点.
Synthesis of β-Benzimidazole Ethylmalonate Dimethyl Esters by Mechanochemical Method Without Solvent
Benzimidazole derivatives have important value in the fields of materials,medicine,chemi-cals,and pesticides,and it is of great significance to develop environmentally friendly and simple methods to synthesize these compounds.In this article,the mechanochemistry method was used to take the donor-acceptor cyclopropanes dimethyl ester and benzimidazole as raw materials.By screening dif-ferent Lewis acids,liquid grinding aids,reaction time,and vibration frequency,the experimental con-ditions were finally determined:Yb(OTf)3 as catalyst,vibration frequency of 35 Hz,and ball milling reaction time of 1.5 h.Finally,ten β-Benzimidazole ethyl dimethyl malonate compounds(3a～3j)were synthesized with yields of 42.9%to 77.5%,their structures were characterized by 1 H NMR,HR-MS(ESI).This synthesis method has the advantages of mild reaction conditions,simple opera-tion,solvent-free,and good substrate expansion.
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