One-pot regioselective synthesis of substituted pyrazoles and isoxazoles in PEG-400/water medium by Cu-free nano-Pd catalyzed sequential acyl Sonogashira coupling–intramolecular cyclization
作者:Narasimha Swamy Thirukovela、Ramesh Balaboina、Vinayak Botla、Ravinder Vadde、Sreekantha Babu Jonnalagadda、Chandra Sekhar Vasam
DOI:10.1039/c9cy01335k
日期:——
Catalyst efficacy of in situ generated Pd-nanoparticles (PdNPs) in the regioselective one-pot synthesis of 3,5-di & 3,4,5-trisubstituted pyrazoles and 3,5-disubstituted isoxazoles in environmentally benign PEG-400/H2O medium, which involves the sequential (i) Cu-free acyl-Sonogashira coupling (ASC) and (ii) intramolecular ynone–amine cyclization under PTC conditions was described. The results of controlled
在环境友好的PEG-400 / H 2中原位生成的Pd-纳米颗粒(PdNPs)在区域选择性一锅合成3,5-di和3,4,5-三取代的吡唑和3,5-二取代的异恶唑的催化剂效力描述了一种O介质,它涉及(i)在PTC条件下无Cu的酰基-Sonogashira偶联(ASC)和(ii)分子内的ynone-amine环化。受控实验的结果支持两个连续的催化循环(ASC /环化)的操作,并通过一锅法通过与炔酮结合的钯实现互补/相反的区域选择性。而且,就地一锅法反应序列的第一个催化循环后回收的PdNPs已连续五次再次使用。此外,在进行上述研究之前,某些常见的Pd-N-杂环卡宾(Pd-NHC)配合物在水和有机物中催化相同的一锅两步反应顺序(无铜ASC /环化)的功效还优化了溶剂。还可以从水中的Pd-NHC上方原位生成PdNP,但由于它们的尺寸较大,因此无法重复使用。