A number of vicinal amino- and (N-acetylamino)-alkylpyrazoles have been synthesized by cross-coupling reactions of iodopyrazoles with alk-1-ynes using a combination of Pd(PPh3)2Cl2 and CuI as catalyst in Et3N or with copper acetylides. The latter Stephens–Castro reaction of copper acetylides with these amino- and (N-acetylamino)-iodopyrazoles was established as a common method for the preparation of (N-acetylamino)alkynylpyrazoles. The Pd/Cu-catalyzed cross-coupling of iodopyrazoles (Sonogashira reaction) with alk-1-ynes bearing electron-releasing substituents was unsuitable for the synthesis of alkynylpyrazoles: 3- and 5-iodopyrazoles were unreactive but, in the case of 4-iodo derivatives, reductive deiodination, accompanied by homocoupling of the alk-1-yne component, was the only reaction.
通过使用Pd(PPh3)2Cl2和CuI作为催化剂在Et3N中,或与
铜炔化物的组合,合成了一系列邻位
氨基和(N-乙酰
氨基)烷基
吡唑。这种
铜炔化物与这些
氨基和(N-乙酰
氨基)
碘吡唑的斯蒂芬斯-卡斯特罗反应被确立为制备(N-乙酰
氨基)炔基
吡唑的常用方法。使用Pd/Cu催化的
碘吡唑(索诺加希拉反应)与具有电子供给取代基的烷-1-炔的交叉耦合不适合合成炔基
吡唑:3-和5-
碘吡唑不反应,但在4-
碘衍
生物的情况下,只有还原去
碘反应发生,同时伴随烷-1-炔组分的同偶联反应。