Chemoselectivity in the Kosugi-Migita-Stille coupling of bromophenyl triflates and bromo-nitrophenyl triflates with (ethenyl)tributyltin
作者:Nurul N. Ansari、Matthew M. Cummings、Björn C.G. Söderberg
DOI:10.1016/j.tet.2018.02.051
日期:2018.5
bis(triphenylphosphine)palladium dichloride (2 mol-%) in 1,4-dioxane at reflux. In contrast, reactions using the same pre-catalyst but in the presence of a three-fold excess of lithium chloride in N,N-dimethylformamide at ambient temperature were in most cases selective for coupling at the carbon-triflate bond. Overall, isolated yields and the selectivity for carbon-bromine bond coupling were significantly higher compared
为了确定在不同反应条件下碳-溴与三氟甲磺酸酯键的化学选择性,研究了(乙烯基)三丁基锡与三氟甲基溴苯磺酸盐和三氟甲基溴硝基苯酚的所有异构排列的Kosugi-Migita-Stille交叉偶联反应。通常,在回流下使用例如在1,4-二恶烷中的双(三苯基膦)二氯化钯(2mol%)观察到高选择性的碳-溴键交叉偶联。相反,使用相同的预催化剂但在N,N中存在三倍过量的氯化锂的情况下进行反应在大多数情况下,在环境温度下β-二甲基甲酰胺对在三氟甲磺酸酯碳键上的偶联具有选择性。总体而言,与三氟甲磺酸碳键合相比,分离的产率和碳-溴键合的选择性高得多。