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Catalytic Dynamic Kinetic Resolutions in Tandem to Construct Two-Axis Terphenyl Atropisomers
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-08-28 , DOI: 10.1021/jacs.0c08057
Omar M Beleh 1 , Edward Miller 2 , F Dean Toste 2 , Scott J Miller 1
Affiliation  

The defined structure of molecules bearing multiple stereogenic axes is of increasing relevance to materials science, pharmaceuticals, and catalysis. However, catalytic enantioselective approaches to control multiple stereogenic axes remain synthetically challenging. We report the catalytic synthesis of two-axis terphenyl atropisomers, with complementary strategies to both chlorinated and brominated variants, formed with high diastereo- and enantioselectivity. The chemistry proceeds through a sequence of two distinct dynamic kinetic resolutions: first, an atroposelective ring-opening of Bringmann-type lactones produces a product with one established axis of chirality; second, a stereoselective arene halogenation delivers the product with the second axis of chirality established. In order to achieve these results, a class of Brønsted basic guanidinylated peptides, which catalyze an efficient atroposelective chlorination, is reported for the first time. In addition, a complementary bromination is reported, which also establishes the second stereogenic axis. These bromo-terphenyls are accessible following the discovery that chiral anion phase transfer catalysis by C2-symmetric phosphoric acids allows catalyst control in the second stereochemistry-determining event. Accordingly, we established the fully catalyst-controlled stereodivergent synthesis of all possible chlorinated stereoisomers, while also demonstrating diastereodivergence in the brominated variants, with significant levels of enantioselectivity in both cases.

中文翻译:

串联催化动态动力学拆分构建双轴三联苯阻转异构体

带有多个立体轴的分子的定义结构与材料科学、制药和催化越来越相关。然而,控制多个立体轴的催化对映选择性方法仍然具有综合挑战性。我们报告了双轴三联苯阻转异构体的催化合成,与氯化和溴化变体的互补策略,形成具有高非对映选择性和对映选择性。该化学过程通过一系列两种不同的动态动力学解析进行:首先,Bringmann 型内酯的阻滞选择性开环产生具有一个既定手性轴的产物;其次,立体选择性芳烃卤化产生具有第二个手性轴的产物。为了达到这些结果,首次报道了一类 Brønsted 碱性胍基肽,其催化有效的 atroposelective 氯化。此外,还报告了互补溴化,这也建立了第二个立体轴。在发现通过 C2 对称磷酸进行的手性阴离子相转移催化允许在第二个立体化学决定事件中控制催化剂之后,这些溴三联苯是可接近的。因此,我们建立了所有可能的氯化立体异构体的完全催化剂控制的立体发散合成,同时还证明了溴化变体的非对映发散,在两种情况下都具有显着的对映选择性。报告了互补溴化,这也建立了第二个立体轴。在发现通过 C2 对称磷酸进行的手性阴离子相转移催化允许在第二个立体化学决定事件中控制催化剂之后,这些溴三联苯是可接近的。因此,我们建立了所有可能的氯化立体异构体的完全催化剂控制的立体发散合成,同时还证明了溴化变体的非对映发散,在两种情况下都具有显着的对映选择性。报告了互补溴化,这也建立了第二个立体轴。在发现通过 C2 对称磷酸进行的手性阴离子相转移催化允许在第二个立体化学决定事件中控制催化剂之后,这些溴三联苯是可接近的。因此,我们建立了所有可能的氯化立体异构体的完全催化剂控制的立体发散合成,同时还证明了溴化变体的非对映发散,在两种情况下都具有显着的对映选择性。
更新日期:2020-08-28
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