Palladium-catalyzed aminocarbonylation of aryl chlorides at atmospheric pressure: The dual role of sodium phenoxide
Palladium-catalyzed aminocarbonylation of aryl chlorides at atmospheric pressure: The dual role of sodium phenoxide
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DOI：
10.1002/anie.200702943
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Buchwald, Stephen L.
中科院分区：
文献类型：
--
作者：
Martinelli, Joseph R.;Clark, Thomas P.;Buchwald, Stephen L.
自从1974年Heck S报告以来，钯催化的羰化反应已经成为区域选择性安装羰基官能团的一种必不可少的方法，并一直是一个活跃的研究领域。在芳基卤化物中，芳基氯化物是这些转化的特别有吸引力的起始原料，因为它们既便宜又商业上丰富。[3]芳基氯化合物的相对化学惰性也使它们更具挑战性，[3]和芳基氯羰化方法与更昂贵的芳基溴、[4]碘、[5]和三氟酸酯[6]变体相比仍然不发达。尤其是，只有有限的方法可以从未活化的芳基氯化物(氨甲酰化)制备酰胺。近20年前，Milstein和他的同事证明了大体积、富含电子的双齿膦配体二(二异丙基膦)丙烷(DIPPP)是钯催化的芳基氯羰化反应的有效配体。[7A]然而，该反应需要高温(1508℃)和高CO压力(70psi)。虽然意义重大，但这项研究的范围有限(它只包括三个氨基甲酰化的例子)，没有讨论官能团的兼容性、邻位取代基的影响或使用二烷基胺以外的试剂。此外，反应条件极大地限制了这种方法在制备化学中的应用，因为温度高，需要专门的压力反应器，以及与处理加压CO相关的危险。最近，Beller和他的同事已经证明，当使用基于二茂铁的电子丰富的双齿双膦配体时，可以使用较低的CO压力进行芳氯碳解反应(1bar)。然而，与米尔斯坦·S的报告一样，这项研究主要集中在酯的形成(烷氧羰化)上，只有一次氨基羰化反应。
Since Heck s seminal reports in 1974, palladium-catalyzed carbonylation has emerged as an indispensable method for the regioselective installation of carbonyl functional groups and remains an area of active research.[1, 2] Among the aryl halides, aryl chlorides are particularly attractive starting materials for these transformations, as they are both inexpensive and commercially abundant.[3] The relative chemical inertness of the aryl chlorides also makes them more challenging substrates,[3] and aryl chloride carbonylation methodologies remain underdeveloped compared to those of the more expensive aryl bromide,[4] iodide,[5] and triflate [6] variants.In particular, only limited methods exist for the preparation of amides from unactivated aryl chlorides (aminocarbonylation). Nearly 20 years ago, Milstein and co-workers demonstrated that the bulky, electron-rich bidentate phosphine ligand bis (diisopropylphophino) propane (dippp) is an effective ligand in palladium-catalyzed aryl chloride carbonylation.[7a] However, the reaction requires high temperature (1508C) and high CO pressure (70 psi). While highly significant, this study was limited in scope (it only included three examples of aminocarbonylation) and did not address functional-group compatibility, the effects of ortho substituents, or the use of reagents other than dialkyl amines. Moreover, the reaction conditions dramatically limit the utility of this method in preparative chemistry because of the high temperature, the need for specialized pressure reactors, and the dangers associated with handling pressurized CO. Recently, Beller and co-workers have shown that lower CO pressures can be used in aryl chloride carbonlyation reactions (1 bar) when electron-rich bidentate bisphosphine ligands based upon ferrocene are employed.[7b, c] However, like Milstein s report, this study focused primarily on the formation of esters (alkoxycarbonylation), with only a single aminocarbonylation