Zuo Group

2023

Science, 2023, 382, 459- 464 DOI: 10.1126/science.adj0040 (the full paper can be accessed for free by clicking on this link)

26. Multiplicative enhancement of stereoenrichment by a single catalyst for deracemization of alcohols Lu Wen†, Jia Ding†, Lingfei Duan†, Shun Wang, Qing An, Hexiang Wang, Zhiwei Zuo*

Multiplicative enhancement of stereoenrichment by a single catalyst for deracemization of alcohols
Lu Wen†, Jia Ding†, Lingfei Duan†, Shun Wang, Qing An, Hexiang Wang, Zhiwei Zuo*
Stereochemical enrichment of a racemic mixture by deracemization must overcome unfavorable entropic effects as well as the principle of microscopic reversibility; recently, photochemical reaction pathways unveiled by the energetic input of light have led to innovations toward this end, most often by ablation of a stereogenic C(sp3)–H bond. We report a photochemically driven deracemization protocol in which a single chiral catalyst effects two mechanistically different steps, C–C bond cleavage and C–C bond formation, to achieve multiplicative enhancement of stereoinduction, which leads to high levels of stereoselectivity. Ligand-to-metal charge transfer excitation of a titanium catalyst coordinated by a chiral phosphoric acid or bisoxazoline efficiently enriches racemic alcohols that feature adjacent and fully substituted stereogenic centers to enantiomeric ratios up to 99:1. Mechanistic investigations support a pathway of sequential radical-mediated bond scission and bond formation through a common prochiral intermediate and reveal that, although the overall stereoenrichment is high, the selectivity in each individual step is moderate.
Chem. Sci., 2023, 14, 6841- 6859 DOI: 10.1039/d3sc01118f

25. [INVITED PERSPECTIVE]Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations Liang Chang; Shun Wang; Qing An; Linxuan Liu; Hexiang Wang; Yubo Li; Kaixuan Feng; Zhiwei Zuo*

Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations
Liang Chang; Shun Wang; Qing An; Linxuan Liu; Hexiang Wang; Yubo Li; Kaixuan Feng; Zhiwei Zuo*
Abstract
The selective functionalization of alkanes has long been recognized as a prominent challenge and an arduous task in organic synthesis. Hydrogen atom transfer (HAT) processes enable the direct generation of reactive alkyl radicals from feedstock alkanes and have been successfully employed in industrial applications such as the methane chlorination process, etc. Nevertheless, challenges in the regulation of radical generation and reaction pathways have created substantial obstacles in the development of diversified alkane functionalizations. In recent years, the application of photoredox catalysis has provided exciting opportunities for alkane C–H functionalization under extremely mild conditions to trigger HAT processes and achieve radical-mediated functionalizations in a more selective manner. Considerable efforts have been devoted to building more efficient and cost-effective photocatalytic systems for sustainable transformations. In this perspective, we highlight the recent development of photocatalytic systems and provide our views on current challenges and future opportunities in this field.
Chem. Comm., 2023, 59, 4055- 4058 DOI: 10.1039/d3cc00532a

24. [INVITED THEME ISSUE]Selective oxidation of benzylic alcohols via synergistic bisphosphonium and cobalt catalysis Jia Ding†; Shuaishuai Luo†; Yuanli Xu; Qing An; Yi Yang; Zhiwei Zuo*

Selective oxidation of benzylic alcohols via synergistic bisphosphonium and cobalt catalysis
Jia Ding†; Shuaishuai Luo†; Yuanli Xu; Qing An; Yi Yang; Zhiwei Zuo*
Abstract
A synergistic photocatalytic system using a bisphosphonium catalyst and a cobalt catalyst has been developed, enabling the selective oxidation of benzylic alcohols under oxidant-free and environmentally benign conditions. High efficiencies have been obtained for a variety of alcohol substrates, and exclusive selectivity for aldehyde products has been achieved across the board. Furthermore, this photocatalytic system proved to be efficient when performed under continuous-flow conditions, even using a simple and easily assembled continuous-flow setup.
J. Am. Chem. Soc., 2023, 145, 1, 359– 376. DOI: 10.1021/jacs.2c10126

23. Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C–H Functionalization Qing An; Yang-Yang Xing; Ruihua Pu; Menghui Jia; Yuegang Chen; Anhua Hu; Shuo-Qing Zhang, Shuoqing Zhang; Na Yu, Jianbo Du, Yanxia Zhang, Jinquan Chen*, Weimin Liu*, Xin Hong*, and Zhiwei Zuo*

Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C–H Functionalization
Qing An; Yang-Yang Xing; Ruihua Pu; Menghui Jia; Yuegang Chen; Anhua Hu; Shuo-Qing Zhang, Shuoqing Zhang; Na Yu, Jianbo Du, Yanxia Zhang, Jinquan Chen*, Weimin Liu*, Xin Hong*, and Zhiwei Zuo*
The intermediacy of alkoxy radicals in cerium-catalyzed C–H functionalization via H-atom abstraction has been unambiguously confirmed. Catalytically relevant Ce(IV)–alkoxide complexes have been synthesized and characterized by X-ray diffraction. Operando electron paramagnetic resonance and transient absorption spectroscopy experiments on isolated pentachloro Ce(IV) alkoxides identified alkoxy radicals as the sole heteroatom-centered radical species generated via ligand-to-metal charge transfer (LMCT) excitation. Alkoxy-radical-mediated hydrogen atom transfer (HAT) has been verified via kinetic analysis, density functional theory (DFT) calculations, and reactions under strictly chloride-free conditions. These experimental findings unambiguously establish the critical role of alkoxy radicals in Ce-LMCT catalysis and definitively preclude the involvement of chlorine radical. This study has also reinforced the necessity of a high relative ratio of alcohol vs Ce for the selective alkoxy-radical-mediated HAT, as seemingly trivial changes in the relative ratio of alcohol vs Ce can lead to drastically different mechanistic pathways. Importantly, the previously proposed chlorine radical–alcohol complex, postulated to explain alkoxy-radical-enabled selectivities in this system, has been examined under scrutiny and ruled out by regioselectivity studies, transient absorption experiments, and high-level calculations. Moreover, the peculiar selectivity of alkoxy radical generation in the LMCT homolysis of Ce(IV) heteroleptic complexes has been analyzed and back-electron transfer (BET) may have regulated the efficiency and selectivity for the formation of ligand-centered radicals.

2022

Chem. Rev., 2022, 122, 2, 2429– 2486. DOI: 10.1021/acs.chemrev.1c00256

22. [INVITED REVIEW]Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis Liang Chang; Qing An; Lingfei Duan; Kaixuan Feng; Zhiwei Zuo*

Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis
Liang Chang; Qing An; Lingfei Duan; Kaixuan Feng; Zhiwei Zuo*
Abstract
Alkoxy radicals are highly reactive species that have long been recognized as versatile intermediates in organic synthesis. However, their development has long been impeded due to a lack of convenient methods for their generation. Thanks to advances in photoredox catalysis, enabling facile access to alkoxy radicals from bench-stable precursors and free alcohols under mild conditions, research interest in this field has been renewed. This review comprehensively summarizes the recent progress in alkoxy radical-mediated transformations under visible light irradiation. Elementary steps for alkoxy radical generation from either radical precursors or free alcohols are central to reaction development; thus, each section is categorized and discussed accordingly. Throughout this review, we have focused on the different mechanisms of alkoxy radical generation as well as their impact on synthetic utilizations. Notably, the catalytic generation of alkoxy radicals from abundant alcohols is still in the early stage, providing intriguing opportunities to exploit alkoxy radicals for diverse synthetic paradigms.

2021

J. Am. Chem. Soc., 2021, 143, 13, 4896– 4902. DOI: 10.1021/jacs.1c00618

21. Photocatalytic Dehydroxymethylative Arylation by Synergistic Cerium and Nickel Catalysis Yuegang Chen; Xin Wang; Xu He; Qing An; Zhiwei Zuo*

Photocatalytic Dehydroxymethylative Arylation by Synergistic Cerium and Nickel Catalysis
Yuegang Chen; Xin Wang; Xu He; Qing An; Zhiwei Zuo*
Abstract
Under mild reaction conditions with inexpensive cerium and nickel catalysts, easily accessible free alcohols can now be utilized as operationally simple and robust carbon pronucleophiles in selective C(sp3)–C(sp2) cross-couplings. Facilitated by automated high-throughput experimentation, sterically encumbered benzoate ligands have been identified for robust cerium complexes, enabling the synergistic cooperation of cerium catalysis in the emerging metallaphotoredox catalysis. A broad range of free alcohols and aromatic halides can be facilely employed in this transformation, representing a new paradigm for the C(sp3)–C(sp2) bond construction between free alcohols and aryl halides with the extrusion of formaldehyde. Moreover, mechanistic investigations have been conducted, leading to the identification of a tribenzoate cerium(III) complex as a viable intermediate.
Angew. Chem. Int. Ed., 2021,60, 5370– 5376. DOI: 10.1002/anie.202012720

20. Photocatalytic Aerobic Oxidative Ring Expansion of Cyclic Ketones to Macrolactones by Cerium and Cyanoanthracene Catalysis Jianbo Du†; Xiaokun Yang†; Xin Wang; Qing An; Xu He; Hui Pan; Zhiwei Zuo*

Photocatalytic Aerobic Oxidative Ring Expansion of Cyclic Ketones to Macrolactones by Cerium and Cyanoanthracene Catalysis
Jianbo Du†; Xiaokun Yang†; Xin Wang; Qing An; Xu He; Hui Pan; Zhiwei Zuo*
Abstract
Challenging macrolactones can now be modularly assembled through a photocatalytic aerobic oxidative ring expansion of cyclic ketones. With the assistance of an organophotocatalyst, α-alkoxyketones can be transformed into macrolactones with 20 min of blue LED irradiation, ultimately enabling the rapid assembly of a large collection of structurally diverse lactones.

2020

J. Am. Chem. Soc., 2020, 142, 13, 6216– 6226 DOI: 10.1021/jacs.0c00212

19. Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents An, Q. †; Wang, Z. †; Chen, Y. †; Wang, X.; Zhang, K.; Pan, H.; Liu, W.; Zhiwei Zuo*

Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
An,Q. †; Wang,Z. †; Chen,Y. †; Wang,X.; Zhang,K.; Pan,H.; Liu,W.;Zhiwei Zuo*
Abstract
Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C–H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C–H functionalization.
Chem., 2020, 6, 266– 279. DOI: 10.1016/j.chempr.2019.11.009

18. Selective C-C Bond Scission of Ketones via Visible-Light-Mediated Cerium CatalysisChen, Y.; Du, J.; Zuo, Z.*

Selective C-C Bond Scission of Ketones via Visible-Light-Mediated Cerium Catalysis
Chen, Y.; Du, J.; Zuo, Z.*
Abstract
The Norrish type I reaction represents a powerful approach to cleave C–C bonds of ketones, yet the synthetic application has been limited because of selectivity and practicality problems. Through the catalytic utilization of the ligand-to-metal charge transfer excitation, Chen and colleagues describe a photocatalytic transformation, in which C–C bonds of ketones are exploited as unconventional handles for selective functionalizations. This protocol, with its utilization of blue LED and inexpensive cerium catalyst, has been successfully employed to cleave a broad range of ketones, regardless of cyclic or acyclic, from simple dibenzyl ketone to complex androsterone.

2019

Sci. Bulletin, 2019, 64, 24, 1896– 1901. DOI: 10.1016/j.scib.2019.08.014

17. [INVITED SUBMISSION]Bisphosphonium salt: an effective photocatalyst for the intramolecular hydroalkoxylation of olefins Cheng, H.; Wang, X.; Chang, L.; Chen, Y.; Chu, L.; Zuo, Z.*

Bisphosphonium salt: an effective photocatalyst for the intramolecular hydroalkoxylation of olefins
Cheng, H.; Wang, X.; Chang, L.; Chen, Y.; Chu, L.; Zuo, Z.*
Abstract
The Norrish type I reaction represents a powerful approach to cleave C–C bonds of ketones, yet the synthetic application has been limited because of selectivity and practicality problems. Through the catalytic utilization of the ligand-to-metal charge transfer excitation, Chen and colleagues describe a photocatalytic transformation, in which C–C bonds of ketones are exploited as unconventional handles for selective functionalizations. This protocol, with its utilization of blue LED and inexpensive cerium catalyst, has been successfully employed to cleave a broad range of ketones, regardless of cyclic or acyclic, from simple dibenzyl ketone to complex androsterone.
Chem., 2019, 5, 2742– 2750. DOI: 10.1016/j.chempr.2019.10.020

16. [INVITED HIGHLIGHT]Dearomative [4 + 2] Cycloaddition of Pyridine via Energy-Transfer Catalysis Chang, L.; Chen, Y.; Zuo, Z.*

Dearomative [4 + 2] Cycloaddition of Pyridine via Energy-Transfer Catalysis
Chang, L.; Chen, Y.; Zuo, Z.*
Abstract
In this issue of Chem, Glorius and coworkers report the first photocatalytic dear- omative cycloaddition of pyridine with alkene. High-value isoquinuclidines could be easily assembled from N-cinamoyl picolinamides under mild and oper- ationally simple conditions.
J. Am. Chem. Soc., 2019, 141, 26, 10556– 10564. DOI: 10.1021/jacs.9b05932

15. Dehydroxymethylation of alcohols enabled by cerium photocatalysis Zhang, K.†; Chang, L.†; An, Q.; Wang, X.; Zuo, Z.*

Dehydroxymethylation of alcohols enabled by cerium photocatalysis
Zhang, K.†; Chang, L.†; An, Q.; Wang, X.; Zuo, Z.*
Abstract
Dehydroxymethylation, the direct conversion of alcohol feedstocks as alkyl synthons containing one less carbon atom, is an unconventional and underexplored strategy to exploit the ubiquity and robustness of alcohol materials. Under mild and redox-neutral reaction conditions, utilizing inexpensive cerium catalyst, the photocatalytic dehydroxymethylation platform has been furnished. Enabled by ligand-to-metal charge transfer catalysis, an alcohol functionality has been reliably transferred into nucleophilic radicals with the loss of one molecule of formaldehyde. Intriguingly, we found that the dehydroxymethylation process can be significantly promoted by the cerium catalyst, and the stabilization effect of the fragmented radicals also plays a significant role. This operationally simple protocol has enabled the direct utilization of primary alcohols as unconventional alkyl nucleophiles for radical-mediated 1,4-conjugate additions with Michael acceptors. A broad range of alcohols, from simple ethanol to complex nucleosides and steroids, have been successfully applied to this fragment coupling transformation. Furthermore, the modularity of this catalytic system has been demonstrated in diversified radical-mediated transformations including hydrogenation, amination, alkenylation, and oxidation.
Chin. Sci. Bull., 2019, 64, 13, 1878- 1886 DOI: 10.1360/N972019-00115

14. [INVITED REVIEW] Recent advancement in homogeneous functionalizations of methane Hu, A.; Chang, L.; Zuo, Z.*.
Acta. Chimica. Sinica., 2019, 77, 794-802. DOI: 10.6023/A19050179

13. [INVITED SUBMISSION] Visible Light Photoredox-Induced Smiles Rearrangement Chen, Y.; Chang, L.; Zuo, Z.*

2018

J. Am. Chem. Soc., 2018, 140, 42, 13580– 13585. DOI: 10.1021/jacs.8b08781

12. Cerium-Catalyzed Formal Cycloaddition of Cycloalkanols with Alkenes through Dual Photoexcitation Hu, A.; Chen, Y.; Guo, J.-J.; Yu, N.; An, Q.; Zuo, Z.*

Cerium-Catalyzed Formal Cycloaddition of Cycloalkanols with Alkenes through Dual Photoexcitation
Hu, A.; Chen, Y.; Guo, J.-J.; Yu, N.; An, Q.; Zuo, Z.*
Abstract
We describe a synergistic utilization of cerium photocatalysis and photoinduced electron transfer catalysis that enables an atom- and step-economical ring expansion of readily available cycloalkanols. This operationally simple protocol provides rapid access to privileged and synthetically challenging bridged lactones. The mild catalytic manifold has been adapted to continuous flow for scale-up applications and employed for the concise synthesis of polycyclic core of nepalactones.
Science, 2018, 361, 6403, 668- 672. DOI: 10.1126/science.aat9750

11. Selective functionalization of methane, ethane, and higher alkanes by cerium photocatalysis Anhua, Hu†; Jing-jing Guo†; Pan, H.; Zuo, Z.*

Selective functionalization of methane, ethane, and higher alkanes by cerium photocatalysis
Anhua, Hu†; Jing-jing Guo†; Pan, H.; Zuo, Z.*
Radically transforming light hydrocarbons
The methane, ethane, and propane in natural gas are mostly inert under ambient conditions. Mainly they are burned to produce heat. Hu et al. show that a simple cerium salt paired with an alcohol can catalytically transform these and other simple hydrocarbons into reactive radicals at room temperature (see the Perspective by Kanai). The reactions rely on light to photolytically cleave cerium alkoxide bonds, producing alkoxy radicals that strip H atoms from the hydrocarbons and regenerate the alcohol. The resultant alkyl radicals readily add to azo compounds, olefins, and aromatics.
Tetrahedron Lett., 2019, 59, 2103- 2111. DOI: 10.1016/j.tetlet.2018.04.060

10. [INVITED REVIEW] Photocatalytic alkoxy radical-mediated transformations Jing-Jing Guo; Anhua Hu; Zhiwei Zuo*
J. Am. Chem. Soc., 2018, 140, 5, 1612–1616 DOI: 10.1021/jacs.7b13131

9. δ-Selective Functionalization of Alkanols Enabled by Visible-Light-Induced Ligand-to-Metal Charge Transfer Anhua Hu†; Jing-Jing Guo†; Hui Pan; Haoming Tang; Zhaobo Gao; Zhiwei Zuo*

δ-Selective Functionalization of Alkanols Enabled by Visible-Light-Induced Ligand-to-Metal Charge Transfer
Anhua Hu†; Jing-Jing Guo†; Hui Pan; Haoming Tang; Zhaobo Gao; Zhiwei Zuo*
Abstract
We demonstrate the application of ligand-to-metal charge transfer (LMCT) excitation to the direct catalytic generation of energetically challenging alkoxy radicals from alcohols through a coordination–LMCT–homolysis process with an abundant and inexpensive cerium salt as the catalyst. This catalytic manifold provides a simple and efficient way to utilize the characteristic reactivity and selectivity of transient alkoxy radicals for δ-selective C–H bond functionalization. Under mild redox-neutral conditions without the need for prefunctionalization, this method provides a versatile platform to access molecular complexity from simple and abundant alcohols.

2016

Angew. Chem. Int. Ed., 2016, 55, 15319–15322. DOI: 10.1002/anie.201609035

8. Photocatalytic C−C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex Jing-Jing Guo†, Anhua Hu†, Yilin Chen, Jianfeng Sun, Haoming Tang, Zhiwei Zuo*

Photocatalytic C−C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex
Jing-Jing Guo†, Anhua Hu†, Yilin Chen, Jianfeng Sun, Haoming Tang, Zhiwei Zuo*
Abstract
Breaking (D)BAD: A general strategy for the cleavage and amination of C−C bonds of cycloalkanols has been achieved through visible-light-induced photoredox catalysis utilizing a cerium(III) chloride complex. This method represents the first example of catalytic C−C bond cleavage and functionalization of unstrained secondary cycloalkanols. DBAD=di-tert-butyl azodicarboxylate, Boc=tert-butoxycarbonyl.

Independent Research Work

J. Am. Chem. Soc., 2016, 138, 6, 1832–1835. DOI: 10.1021/jacs.5b13211

7. Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis Zuo, Z.†; Cong, H.†; Li, W.; Choi, J.; Fu, G.C.*; MacMillan, D.W.C.*
J. Am. Chem. Soc., 2014, 136, 31, 10886–10889. DOI: 10.1021/ja505964r

6. Carboxylic acids as A traceless activation group for conjugate additions: A three-step synthesis of (±)-pregabalin Chu, L.; Ohta, C.; Zuo, Z.; MacMillan, D.W.C.*
J. Am. Chem. Soc., 2014, 136, 14, 5257–5260. DOI: 10.1021/ja501621q

5. Decarboxylative arylation of α-Amino acids via photoredox catalysis: A one-step conversion of biomass to drug pharmacophore Zuo, Z.; Macmillan, D.W.C.*
Science, 2014, 345, 6195, 437- 440. DOI: 10.1126/science.1255525

4. Merging photoredox with nickel catalysis: Coupling of α-carboxyl sp3-carbons with aryl halides Zuo, Z.; Ahneman, D.T.; Chu, L.; Terrett, J.A.; Doyle, A.G.*; MacMillan, D.W.C.*
Isr. J. Chem., 2011, 51, 434- 441. DOI: 10.1002/ijch.201100014

3. [REVIEW] Synthetic studies toward communesinsZuo, Z.; Ma, D.*
Angew. Chem. Int. Ed., 2011, 50(50):12008-11. DOI: 10.1021/ja501621q

2. Enantioselective total syntheses of communesins A and B Zuo, Z.; Ma, D.*
J. Am. Chem. Soc., 2010, 132, 38, 13226–13228. DOI: 10.1021/ja106739g

1. Total synthesis and absolute stereochemical assignment of (-)-communesin F Zuo, Z.; Xie, W.; Ma, D.*

Publications

2023

2022

2021

2020

2019

2018

2016

Independent Research Work