铜催化腙酰卤与端炔的串联反应制备1,3,5-三取代吡唑衍生物

Preparation of 1,3,5-Trisubstituted Pyrazoles with Cascade Reaction Catalyzed by Cu between Hydrazonoyl Halide and Terminal Alkynes

末端炔烃在亚铜盐的催化条件下,能够与取代芳基腙酰卤通过亲核取代及加成环化的串联反应生成1,3,5-三取代吡唑衍生物.该方法采用易合成的芳基腙酰卤和末端炔烃作为起始原料,在45℃的加热条件下,以绿色溶剂乙腈和水作为反应介质,高产率、区域专一性地生成1,3,5-三取代吡唑产物.而且该反应不受含活泼氢(羟基、羧基等)取代基的影响,通过该方法制备了17种包含不同类型取代基的吡唑衍生物,可作为1,3,5-三取代吡唑类化合物的通用合成法.

Cascade reaction, including nucleophilic substitution and addition cyclization, catalyzed by Cu＋ salt between substituted aryl hydrazonoyl halides and terminal alkynes could produce 1,3,5-trisubstituted pyrazoles. The method employed easily available aryl hydrazonoyl halide and terminal alkynes as starting materials under 45 ℃ in green acetonitrile/water solvent, regioselectively generating 1,3,5-trisubstituted pyrazoles in high yield. Above all, functional groups containing active hydrogen would not disturb this reaction, example for carboxyl and hydroxyl. In this work 17 pyrazole derivatives with different substituent group were achieved by this method. So it could be a general method to synthesize 1,3,5-trisubstituted pyrazoles.