Cycloalkenyl nonaflates as electrophilic cross-coupling substrates for palladium catalyzed C–N bond forming reactions with enolizable heterocycles under microwave enhanced conditions
作者:K. K. Abdul Khader、Ayyiliath. M. Sajith、M. Syed Ali Padusha、H. P. Nagaswarupa、A. Muralidharan
DOI:10.1039/c3nj01355c
日期:——
Microwave-mediated, palladium catalyzed CâN bond forming reactions with activated cycloalkenyl nonaflates and enolizable heterocycles using cesium carbonate as a base and a catalytic system employing Pd(OAc)2/Xantphos or Pd(OAc)2/dppp were found to be effective in driving the reactions to completion. This method resulted in good to excellent yields of the coupled products (22 examples, 25â90%) in short reaction time (30â60 min). Under optimum conditions, cycloalkenyl nonaflates were found to be an effective alternative to analogous triflates in CâN bond forming processes due to their increased stability under the reaction conditions. The use of tetrabutylammonium bromide (Bu4NBr) as an additive in these transformations proved to be effective and resulted in better yields of the coupled products.
微波介导的钯催化C-N键形成反应中,使用活性环烯基壬二酸酯和可烯醇化的杂环化合物,以碳酸铯为碱,采用Pd(OAc)2/Xantphos或Pd(OAc)2/dppp催化系统,已被证明能有效地推动反应完成。该方法在短时间内(30-60分钟)实现了良好至极佳的耦合产物收率(22个例子,25%-90%)。在最佳条件下,环烯基壬二酸酯因其反应条件下的增强稳定性,被发现是在C-N键形成过程中类似于三氟甲磺酸酯的有效替代品。在这些转化过程中使用四丁基溴化铵(Bu4NBr)作为添加剂被证明是有效的,并导致耦合产物的收率提高。