Palladium-Catalyzed Cross-Methylation of Aryl Chlorides by Stabilized Dimethylaluminium and -Gallium Reagents
作者:Jochanan Blum、Olga Berlin、David Milstein、Yehoshua Ben-David、Birgit C. Wassermann、Stefan Schutte、Herbert Schumann
DOI:10.1055/s-2000-6373
日期:——
Two methods for palladium-catalyzed cross-methylation of aryl chlorides by intramolecularly stabilized dialkylaluminium and -gallium complexes 6-13 have been studied. In one method, in which either tetrakis(triphenylphosphine)palladium (1) or dichlorobis(triphenylphosphine)palladium (2) is used as the catalyst at 80-90 °C, the activation of the chlorine atom is affected by introduction of strong electron-withdrawing groups into the aromatic moiety. The second method is based on the application of either [1,3-bis(diisopropylphosphino)propane)]palladium (4) or homologous electron-rich palladium complexes as catalysts. Although 4 promotes smooth cross-alkylation of aryl chlorides it fails to activate simple aryl bromides.
研究了两种使用分子内稳定的双烷基铝和镓复合物6-13进行钯催化的芳基氯交叉甲基化的方法。在第一种方法中,使用四(三苯基膦)钯(1)或二氯双(三苯基膦)钯(2)作为催化剂,在80-90°C下,通过向芳香环引入强吸电子基团来实现氯原子的活化。第二种方法基于应用[1,3-双(二异丙基膦)丙烷]钯(4)或相邻的富电子钯复合物作为催化剂。尽管4促进了芳基氯的平滑交叉烷基化,但无法活化简单的芳基溴。