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168 results on '"Fu, Niankai"'

14. Dual electrocatalysis enables enantioselective hydrocyanation of conjugated alkenes

Author

Song, Lu, Fu, Niankai, Ernst, Brian G., Lee, Wai Hang, Frederick, Michael O., DiStasio, Robert A., and Lin, Song

Abstract

Chiral nitriles and their derivatives are prevalent in pharmaceuticals and bioactive compounds. Enantioselective alkene hydrocyanation represents a convenient and efficient approach for synthesizing these molecules. However, a generally applicable method featuring a broad substrate scope and high functional group tolerance remains elusive. Here, we address this long-standing synthetic problem using dual electrocatalysis. Using this strategy, we leverage electrochemistry to seamlessly combine two canonical radical reactions—cobalt-mediated hydrogen-atom transfer and copper-promoted radical cyanation—to accomplish highly enantioselective hydrocyanation without the need for stoichiometric oxidants. We also harness electrochemistry’s unique feature of precise potential control to optimize the chemoselectivity of challenging substrates. Computational analysis uncovers the origin of enantio-induction, for which the chiral catalyst imparts a combination of attractive and repulsive non-covalent interactions to direct the enantio-determining C–CN bond formation. This work demonstrates the power of electrochemistry in accessing new chemical space and providing solutions to pertinent challenges in synthetic chemistry.

Published
2024
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22. Electrochemical Metal‐Catalyzed Azidoesterification of Alkenes.

Author

Zhou, Kehan, Lv, Chenglei, and Fu, Niankai

Subjects
ALKENES, ACID derivatives, METAL complexes
Abstract

We report an efficient and sustainable electrocatalytic approach for azidoesterification of alkenes. The reaction proceeds by electrochemical iron‐catalyzed oxidation of commercially available carbazates to produce alkoxycarbonyl radicals. Upon addition across alkenes, the generated transient carbon‐centered radicals get trapped by azido metal complexes to furnish the alkene difunctionalization products. This mild, operationally simple protocol transforms a wide variety of alkenes into the corresponding β‐azido esters in good to excellent yields, thereby providing a practical access to β‐amino acid derivatives from simple and readily available starting materials. [ABSTRACT FROM AUTHOR]

Published
2023
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32. Anodically Coupled Electrolysis for the Heterodifunctionalization of Alkenes

Author

Ye, Ke-Yin, Pombar, Gisselle, Fu, Niankai, Sauer, Gregory S., Keresztes, Ivan, and Lin, Song

Abstract

The emergence of new catalytic strategies that cleverly adopt concepts and techniques frequently used in areas such as photochemistry and electrochemistry has yielded a myriad of new organic reactions that would be challenging to achieve using orthodox methods. Herein, we discuss the strategic use of anodically coupled electrolysis, an electrochemical process that combines two parallel oxidative events, as a complementary approach to existing methods for redox organic transformations. Specifically, we demonstrate anodically coupled electrolysis in the regio- and chemoselective chlorotrifluoromethylation of alkenes.

Published
2024
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43. Electrochemical Azidooxygenation of Alkenes Mediated by a TEMPO–N3Charge-Transfer Complex

Author

Siu, Juno C., Sauer, Gregory S., Saha, Ambarneil, Macey, Reed L., Fu, Niankai, Chauviré, Timothée, Lancaster, Kyle M., and Lin, Song

Abstract

We report a mild and efficient electrochemical protocol to access a variety of vicinally C–O and C–N difunctionalized compounds from simple alkenes. Detailed mechanistic studies revealed a distinct reaction pathway from those previously reported for TEMPO-mediated reactions. In this mechanism, electrochemically generated oxoammonium ion facilitates the formation of azidyl radical via a charge-transfer complex with azide, TEMPO–N3. DFT calculations together with spectroscopic characterization provided a tentative structural assignment of this charge-transfer complex. Kinetic and kinetic isotopic effect studies revealed that reversible dissociation of TEMPO–N3into TEMPO•and azidyl precedes the addition of these radicals across the alkene in the rate-determining step. The resulting azidooxygenated product could then be easily manipulated for further synthetic elaborations. The discovery of this new reaction pathway mediated by the TEMPO+/TEMPO•redox couple may expand the scope of aminoxyl radical chemistry in synthetic contexts.

Published
2018
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