Copper-Catalyzed C-P Coupling through Decarboxylation
Copper-Catalyzed C-P Coupling through Decarboxylation
复制标题
铜催化脱羧 C-P 偶联
DOI：
10.1002/chem.201003561
复制
发表时间：
2011-05-01
影响因子：
4.3
通讯作者：
Yang, Shang-Dong
中科院分区：
文献类型：
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作者：
Hu, Jie;Zhao, Ning;Yang, Shang-Dong
CÀP 键构建对于修饰核苷、核苷酸和其他含膦配体的合成非常重要。 [1]一般方法涉及过渡金属催化的芳基卤化物或三氟甲磺酸酯与仲膦的交叉偶联，或通过 R2P (O) M（M= Li、Na、K 等）试剂加成烯烃/炔烃 [方案 1，方程（1）]。 [2]然而，一般来说，只有高反应性芳基碘化物才能用作偶联配偶体，或者需要特定且昂贵的配体来促进高反应性。此外，敏感且昂贵的膦金属的制备通常很复杂。作为一种实用的替代方案，过渡金属催化的脱羧偶联反应很有吸引力，因为：1）羧酸便宜、稳定且易于获得各种结构； 2) 羧酸官能团保证了反应的区域选择性； 3）仅产生二氧化碳，而不产生金属卤化物。 Nilsson 和 Cohen 及其同事报道了开创性的工作，他们发现铜有效促进芳香酸的脱羧。 [3]最近，古森、迈尔斯和刘等人。开发了一种新的脱羧偶联方案，并将其广泛应用于 C-C 键形成；[4] 然而，金属介导的 C-P 键形成的例子尚未见报道。在此，我们描述了一种通过铜催化的烯基酸、炔酸和 N-苄基脯氨酸分别与 R2P (O) H 化合物脱羧偶联来构建 CÀP 键的通用方法 [方案 1，方程 (2)]。据我们所知，本报告是铜催化脱羧偶联构建 CÀP 键的第一个例子。在初步研究中，我们选择肉桂酸 (1a) 和 Ph2P (O) H 作为模型底物来开始我们的研究，因为烯基二ACHTUNGTRENNUNG（苯基）氧化膦是合成各种膦配体的关键中间体，并存在于许多生物活性产品中。 [5]构建此类结构单元的通用方法是过渡金属催化Ph2P(O)H与炔烃的加成，但这种转化总是导致E/Z构型的混合物，并且很难获得单一产物。 [6]另一种方法是通过 Heck 型反应将烯基膦酸酯与芳基碘化物偶联。 [7]然而，烯基膦酸酯的制备和芳基碘化物的可用性限制了其应用。鉴于最佳的区域选择性和价格，烯基酸与Ph2P(O)H的脱羧偶联为烯基氧化膦的合成提供了直接有效的方法。我们在 1208℃ 下以 CuCl (10 mol%) 和 1, 10-菲咯啉 (10 mol%) 作为配体在 N-甲基吡咯烷酮 (NMP) 中进行了初步测试（表 1，条目 1），但没有观察到所需的产物。当加入 AgOAc（2.0 当量）时，反应 [a] J. Hu, N. Zhao, B. Yang, G. Wang, L.-N.郭Y.-M.教授。梁，S.-D。杨
CÀP bond construction is highly important in the synthesis of modified nucleosides, nucleotides, and other phosphine-containing ligands.[1] General methods involve transition-metal-catalyzed cross-coupling of aryl halides or triflates with secondary phosphines, or addition of olefin/alkyne by R2P (O) M (M= Li, Na, K, etc.) reagents [Scheme 1, Eq.(1)].[2] However, in general, only highly reactive aryl iodides can be used as coupling partners or specific and expensive ligands are required to facilitate the high reactivities. In addition, preparation of sensitive and costly phosphine metals is often complicated. As a practical alternative, transition-metal-catalyzed decarboxylative coupling reactions are attractive because: 1) carboxylic acids are cheap, stable, and readily available in various structures; 2) the carboxylic-acid function ensures regioselectivity of the reaction; and 3) only carbon dioxide is produced, instead of metal halides. Pioneering work was reported by Nilsson and Cohen and co-workers, they discovered that copper effectively promotes decarboxylation of aromatic acids.[3] Recently, Gooßen, Myers, and Liu et al. developed a novel protocol for the decarboxylative coupling and widely applied it to CÀC bond formation;[4] however, examples of metalmediated CÀP bond formation has yet to be reported. Herein, we describe a versatile method to construct CÀP bonds by copper-catalyzed decarboxylative coupling of alkenyl acid, alkyne acid, and N-benzylproline, respectively, with R2P (O) H compounds [Scheme 1, Eq.(2)]. To the best of our knowledge, this report is the first example of coppercatalyzed decarboxylative coupling to construct CÀP bonds. In an initial study, we choose cinnamic acid (1a) and Ph2P (O) H as the model substrates to begin our investigations, because alkenyl diACHTUNGTRENNUNG (phenyl) phosphine oxides are key intermediates for the syntheses of various phosphine ligands and present in numerous biologically active products.[5] A general method to build such structure units is the transition-metal-catalyzed addition of Ph2P (O) H to alkynes, but this transformation always results in a mixture of E/Z configurations, and it is difficult to obtain one single product.[6] Another approach is through coupling of alkenyl phosphonates with aryl iodides by Heck-type reactions.[7] However, the preparation of alkenyl phosphonates and the availability of aryl iodides limits the applications. In view of the best regioselectivity and price, alkenyl-acid decarboxylative coupling with Ph2P (O) H provides a direct and effective method for the synthesis of alkenylphosphine oxides. We did initial tests with CuCl (10 mol%) and 1, 10-phenanthroline (10 mol%) as the ligand in N-methylpyrrolidone (NMP) at 1208C (Table 1, entry 1), but did not observe the desired product. When AgOAc (2.0 equiv) was added, the reaction [a] J. Hu, N. Zhao, B. Yang, G. Wang, L.-N. Guo, Prof. Y.-M. Liang, S.-D. Yang