Iridium-catalyzed highly selective reactions

我们研究了以下反应：(1)不对称烯丙基烷基化反应是从非手性底物通过碳-碳键形成反应来构建新的手性中心的最有力的工具之一。这一领域的一个具有挑战性的课题是非对称底物的区域和对映体选择性的烯丙基烷基化。手性亚磷酰胺配体在过渡金属不对称合成中具有重要作用。Helmchen首次使用联萘基亚磷酰胺催化的对映选择性烯丙基烷基化反应。我们设计了一种新型的亚磷酰胺P(OR)_2(酰胺)配体。酰胺基团的平面性强烈地促成了更刚性的手性空间。此外，这种亚磷酰胺配体有望通过羰基氧和磷原子与中心金属的配位而作为手性双齿配体发挥作用。在[Ir(Cod)Cl]_2摩尔分数为2%，配体摩尔质量分数为4%的条件下，通过乙酸肉桂酯与马来酸二乙酯的反应考察了该配体的反应效率。以含恶唑烷酮基团的配体效果最好。烷基化产物的产率为94%，ee为93%，不含LiCl2。(2)多取代苯是天然生物活性分子的常见结构成分。两种或三种不同单炔的区域选择性环三聚反应是合成多取代苯类化合物的一条新的有效途径。然而，控制区域选择性可能会很困难。丙酸甲酯在[Ir(Cod)Cl2]2和FDPPE的催化下，与2个1-炔分子反应，高产率地合成了3，5-二取代苯甲酸酯。摘要乙炔基对甲苯基砜与各种1-炔烃反应，高产率地得到相应的产物。

We have studied the following reactions.(1) Asymmetric allylic alkylation is one of the most powerful tools for constructing a new chiral center via a carbon-carbon bond-forming reaction from an achiral substrate. A challenging topic in this area is the regio- and enantioselective allylic alkylation of nonsymmetrical substrates. Chiral phosphoramidite ligands have become important in transition metal-asymmetric synthesis. Helmchen first used binaphthol-based phosphoramidites for iridium-catalyzed enantioselective allylic alkylation. We designed a novel phosphoramidite P(OR)_2(amide)ligand. The planarity of the amide group strongly contributes to a more rigid chiral space. Furthermore, such a phosphoramidite ligand is expected to act as a chiral bidentate ligand through coordination of the carbonyl oxygen and phosphorous atom to the central metal. The efficiency of the ligand was examined by the reaction of cinhamyl acetate with diethyl sodiomalonate in the presence of 2 mol% of [Ir(cod)Cl]_2 and 4 mol% of ligand. The best result was obtained with a ligand bearing an oxazolidinone moiety. The alkylated product was obtained in 94% yield with 93% ee without LiCl.(2) Polysubstituted benzenes are a common structural component of naturally occurring biologically active molecules. The regioselective cyclotrimerization of two or three different monoynes is a new and efficient route to polysubstituted benzenes. However, it can be difficult to control the regioselectivity. Methyl propiolate reacted with 2 molecules of 1-alkyne to give 3, 5-disubstituted benzoate in high yield in the presence of a catalytic amount of [Ir(cod)Cl]_2 and FDPPE. The reaction of ethynyl p-tolyl sulfone with various 1-alkynes gave the corresponding products in high yields