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Phase Separation-Promoted Redox Deracemization of Secondary Alcohols over a Supported Dual Catalysts System
ChemCatChem ( IF 3.8 ) Pub Date : 2021-08-09 , DOI: 10.1002/cctc.202100738
Zhitong Zhao 1 , Chengyi Wang 1 , Qipeng Chen 1 , Yu Wang 1 , Rui Xiao 1 , Chunxia Tan 1 , Guohua Liu 1
Affiliation  

Unification of oxidation and reduction in a one-pot deracemization process has great significance in the preparation of enantioenriched organic molecules. However, the intrinsic mutual deactivation of oxidative and reductive catalysts and the extrinsic incompatible reaction conditions are unavoidable challenges in a single operation. To address these two issues, we develop a supported dual catalysts system to overcome these conflicts from incompatibility to compatibility, resulting in an efficient one-pot redox deracemization of secondary alcohols. During this transformation, the TEMPO species onto the outer surface of silica nanoparticles catalyze the oxidation of racemic alcohols to ketones, and the chiral Rh/diamine species in the nanochannels of the thermoresponsive polymer-coated hollow-shell mesoporous silica enable the asymmetric transfer hydrogenation (ATH) of ketones to chiral alcohols. To demonstrate the general feasibility, a series of orthogonal oxidation/ATH cascade reactions are compared to prove the compatible benefits in the elimination of their deactivations and the balance of the cascade directionality. As presented in this study, this redox deracemization process provides various chiral alcohols with enhanced yields and enantioselectivities relative to those from unsupported dual catalysts systems. Furthermore, the dual catalysts can be recycled continuously, making them an attractive feature in the application.

中文翻译:

相分离促进仲醇在双催化剂系统上的氧化还原脱消旋

一锅法去消旋过程中氧化和还原的统一对制备富含对映体的有机分子具有重要意义。然而,氧化和还原催化剂的内在相互失活和外在不相容的反应条件是单一操作中不可避免的挑战。为了解决这两个问题,我们开发了一种负载型双催化剂系统来克服这些从不相容性到相容性的冲突,从而实现仲醇的高效一锅氧化还原去消旋。在此转化过程中,二氧化硅纳米粒子外表面上的 TEMPO 物质催化外消旋醇氧化为酮,热响应性聚合物涂层中空壳介孔二氧化硅的纳米通道中的手性 Rh/二胺物质能够实现酮向手性醇的不对称转移氢化 (ATH)。为了证明一般可行性,对一系列正交氧化/ATH 级联反应进行了比较,以证明在消除它们的失活和级联方向性平衡方面的兼容优势。正如本研究中所介绍的那样,这种氧化还原去消旋过程提供了各种手性醇,相对于来自未负载双催化剂系统的那些,具有更高的产率和对映选择性。此外,双催化剂可以连续回收,使其成为应用中的一个有吸引力的特征。对一系列正交氧化/ATH 级联反应进行了比较,以证明在消除其失活和级联方向性平衡方面的兼容优势。正如本研究中所介绍的那样,这种氧化还原去消旋过程提供了各种手性醇,相对于来自未负载双催化剂系统的那些,具有更高的产率和对映选择性。此外,双催化剂可以连续回收,使其成为应用中的一个有吸引力的特征。对一系列正交氧化/ATH 级联反应进行了比较,以证明在消除其失活和级联方向性平衡方面的兼容优势。正如本研究中所介绍的那样,这种氧化还原去消旋过程提供了各种手性醇,相对于来自未负载双催化剂系统的那些,具有更高的产率和对映选择性。此外,双催化剂可以连续回收,使其成为应用中的一个有吸引力的特征。这种氧化还原去外消旋过程提供了各种手性醇,与未负载的双催化剂系统相比,它们具有更高的产率和对映选择性。此外,双催化剂可以连续回收,使其成为应用中的一个有吸引力的特征。这种氧化还原去外消旋过程提供了各种手性醇,与未负载的双催化剂系统相比,它们具有更高的产率和对映选择性。此外,双催化剂可以连续回收,使其成为应用中的一个有吸引力的特征。
更新日期:2021-09-17
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