Difluorocarbene has important applications in pharmaceuticals, agrochemicals and materials, but all these applications proceed using just a few types of reaction by taking advantage of its intrinsic electrophilicity. Here, we report a palladium-catalysed strategy that confers the formed palladium difluorocarbene (Pd=CF2) species with both nucleophilicity and electrophilicity by switching the valence state of the palladium centre (Pd(0) and Pd(ii), respectively). Controllable catalytic difluorocarbene transfer occurs between readily available arylboronic acids and the difluorocarbene precursor diethyl bromodifluoromethylphosphonate (BrCF2PO(OEt)2). From just this simple fluorine source, difluorocarbene transfer enables access to four types of product: difluoromethylated and tetrafluoroethylated arenes and their corresponding fluoroalkylated ketones. The transfer can also be applied to the modification of pharmaceuticals and agrochemicals as well as the one-pot diversified synthesis of fluorinated compounds. Mechanistic and computational studies consistently reveal that competition between nucleophilic and electrophilic palladium difluorocarbene ([Pd]=CF2) is the key factor controlling the catalytic difluorocarbene transfer. Difluorocarbene transfer is mostly limited to reactions that utilize its intrinsic electrophilicity. Now, a controllable palladium-catalysed difluorocarbene transfer reaction is reported that involves nucleophilic and electrophilic palladium difluorocarbene species. The selective reactions between arylboronic acids and the difluorocarbene precursor BrCF2PO(OEt)2 give four different productsâdifluoromethylated and tetrafluoroethylated arenes and their corresponding fluoroalkylated ketones.
二
氟羰基在医药、农用
化学品和材料领域有着重要的应用,但所有这些应用都只是利用其固有的亲电性,通过少数几种反应进行的。在此,我们报告了一种
钯催化策略,通过切换
钯中心的价态(分别为 Pd(0) 和 Pd(ii)),使形成的
钯二
氟碳(Pd=
CF2)物种同时具有亲核性和亲电性。在容易获得的芳基
硼酸和二
氟羰基前体
溴二氟甲基膦酸二乙酯(Br
CF2PO(OEt)2)之间会发生可控的二
氟羰基催化转移。仅从这个简单的
氟源,二
氟碳转移就能获得四种类型的产物:二
氟甲基化和四
氟乙基化的炔类化合物及其相应的氟烷基化
酮类化合物。这种转移还可应用于药品和农用
化学品的改性,以及含
氟化合物的一锅多元合成。机理和计算研究一致表明,亲核和亲电性
钯二
氟碳([Pd]=
CF2)之间的竞争是控制催化二
氟碳转移的关键因素。二
氟碳的转移大多局限于利用其固有亲电性的反应。现在,报告了一种可控的
钯催化二
氟碳转移反应,该反应涉及亲核和亲电的
钯二
氟碳物种。芳基
硼酸与二
氟碳前体 Br
CF2PO(OEt)2 的选择性反应产生了四种不同的产物:二
氟甲基化和四
氟乙基化的炔类化合物及其相应的氟烷基化
酮类化合物。