- CATALYTIC SYSTEMS FOR STEREOSELECTIVE SYNTHESIS OF CHIRAL AMINES BY ENANTIODIVERGENT RADICAL C-H AMINATION
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In one aspect, the disclosure relates to a mode of asymmetric induction in radical processes based on sequential combination of enantiodifferentiative H-atom abstraction and stereoretentive radical substitution. Also disclosed is an asymmetric system for stereoselective synthesis of strained 5-membered cyclic sulfamides via radical 1,5-C—H amination of sulfamoyl azides. The disclosed metalloradical system can control the degree and sense of asymmetric induction in the catalytic radical C—H amination in a systematic manner. The disclosed system is applicable to a broad scope of substrates with different types of C(sp3)-H bonds and exhibits reactivity and selectivity, providing access to both enantiomers of useful 5-membered cyclic sulfamides in a highly enantioenriched form. Also disclosed are catalysts useful in these processes. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.
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Paragraph 0201; 0242; 0272
(2020/11/27)
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- Asymmetric Induction and Enantiodivergence in Catalytic Radical C-H Amination via Enantiodifferentiative H-Atom Abstraction and Stereoretentive Radical Substitution
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Control of enantioselectivity remains a major challenge in radical chemistry. The emergence of metalloradical catalysis (MRC) offers a conceptually new strategy for addressing this and other outstanding issues. Through the employment of D2-symmetric chiral amidoporphyrins as the supporting ligands, Co(II)-based MRC has enabled the development of new catalytic systems for asymmetric radical transformations with a unique profile of reactivity and selectivity. With the support of new-generation HuPhyrin chiral ligands whose cavity environment can be fine-tuned, the Co-centered d-radicals enable to address challenging issues that require exquisite control of fundamental radical processes. As showcased with asymmetric 1,5-C-H amination of sulfamoyl azides, the enantiocontrol of which has proven difficult, the judicious use of HuPhyrin ligand by tuning the bridge length and other remote nonchiral elements allows for controlling both the degree and sense of asymmetric induction in a systematic manner. This effort leads to successful development of new Co(II)-based catalytic systems that are highly effective for enantiodivergent radical 1,5-C-H amination, producing both enantiomers of the strained five-membered cyclic sulfamides with excellent enantioselectivities. Detailed deuterium-labeling studies, together with DFT computation, have revealed an unprecedented mode of asymmetric induction that consists of enantiodifferentiative H-atom abstraction and stereoretentive radical substitution.
- Lang, Kai,Torker, Sebastian,Wojtas, Lukasz,Zhang, X. Peter
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supporting information
p. 12388 - 12396
(2019/08/20)
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- Palladium-Catalyzed Enantioselective C-H Aminocarbonylation: Synthesis of Chiral Isoquinolinones
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A Pd-catalyzed enantioselective C-H carbonylation by desymmetrization was developed with commercially available L-pyroglutamic acid as chiral ligand. Isoquinolinones were successfully obtained with good yields and high enantioselectivities. Mechanistic studies and DFT calculations provided a reasonable reaction pathway.
- Han, Hui,Zhang, Tao,Yang, Shang-Dong,Lan, Yu,Xia, Ji-Bao
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supporting information
p. 1749 - 1754
(2019/03/11)
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