The palladium-catalyzed reactions of tert-propargylic alcohols with aryl iodides afforded tetraarylallenes in good yields. This reaction involves: (1) oxidative addition of the aryl iodide to Pd(0); (2) arylpalladium intermediate coordination to the carbon-carbon triple bond of the 1,1,3-triaryl-2-propyn-1-ol and subsequent regioselective insertion of the alkynol to form β-hydroxyvinylpalladium species; and (3) β-elimination to produce the tetraarylallenes. Generally, the best results are obtained by employing 5 mol% of Pd(TFA)2, 10 mol% of PPh3, two equivalents of aryl iodide and five equivalents of Et3N in MeCN.
钯催化的叔炔
丙醇与芳基
碘的反应可以高效地得到四芳基烯,该反应包括以下步骤:(1) 芳基
碘的氧化加成到Pd(0);(2) 芳基
金属中间体与1,1,3-三芳基-
2-丙炔-1-醇的碳-碳三键配位,随后选择性地插入形成β-羟基
乙烯基钯物种;(3) β-消去反应生成四芳基烯。通常采用5 mol%的Pd(TFA)2、10 mol%的PPh3、两倍的芳基
碘和五倍的Et3N于MeCN溶剂中,可以获得最佳结果。