Full Professor, Wuhan University
Address: The Institute for Advanced Studies (高等研究院),
Wuhan University, Wuhan 430072, P. R. China
Office: 205, Jijian Building
Lab: 515, Dangdai Building
Email: gci2011@whu.edu.cn
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Y. Cao, C. Huang, Q. Lu* __________ _________________________________________________________________
The development of strategies to access boronate esters from ubiquitous aliphatic C−H bonds is of long-standing interest in the synthesis community. Here photoelectrochemically driven C(sp3)−H borylation of alkanes is developed, in which iron, an abundant earth-based resource, is employed as a photoelectrochemical catalyst. Using this protocol, direct borylation of strong alkyl C−H bonds is efciently achieved at a low oxidation potential of ∼0.3 V and mild conditions. A wide range of structurally diverse alkyl boronic esters, including versatile α-silyl boronic esters, can be accessed with good regioselectivity.
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C. Huang#, Y. Tao#, X. Cao, C. Zhou, Q. Lu* __________ _________________________________________________________________
Asymmetric electrocatalysis offers exciting new strategies for the synthesis of chiral molecules through novel reaction pathways. However, simultaneous activation of reactants on both electrodes via asymmetric paired electrolysis, which is more energy efficient and economic than single half-electrode synthesis, remains a formidable challenge. Herein, an asymmetric olefin–sulfonylimine coupling via paired electrocatalysis is presented for the first time. In this protocol, Co-catalyzed hydrogen atom transfer on the anode and Ni-catalyzed sulfonylimine reduction on the cathode were seamlessly cross-coupled. The new catalytic system enables the formation of chiral amine products bearing a tetrasubstituted carbon stereocenter with a high enantioselectivity (up to 96% ee).
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L. Zou, S. Xiang, R. Sun, Q. Lu* __________ _________________________________________________________________
We report a combination of electrocatalysis and photoredox catalysis to perform selective C(sp3)–H arylation/alkylation of alkanes, in which a binary catalytic system based on earth-abundant iron and nickel is applied. Reaction selectivity between two-component C(sp3)–H arylation and three-component C(sp3)–H alkylation is tuned by modulating the applied current and light source. Importantly, an ultra-low anodic potential (~0.23 V vs. Ag/AgCl) is applied in this protocol, thus enabling compatibility with a variety of functional groups (>70 examples). The robustness of the method is further demonstrated on a preparative scale and applied to late-stage diversification of natural products and pharmaceutical derivatives.
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L. Zou, X. Wang, S. Xiang, W. Zheng, Q. Lu* __________ _________________________________________________________________
Due to the intrinsic inertness of alkanes, strong oxidative conditions are typically required to enable their C(sp3)−H functionalization. Herein, a paired electrocatalysis strategy was developed by integrating oxidative catalysis with reductive catalysis in one cell without interference, in which earth-abundant iron and nickel are employed as the anodic and cathodic catalysts, respectively. This approach lowers the previously high oxidation potential required for alkane activation, enabling electrochemical alkane functionalization at the ultra-low oxidation potential of ~0.25 V vs. Ag/AgCl under mild conditions. Structurally diverse alkenes, including challenging all-carbon tetrasubstituted olefins, can be accessed using readily available alkenyl electrophiles.
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P. Peng, Y. Zhong, C. Zhou, Y. Tao, D. Li, Q. Lu* __________ _________________________________________________________________
Direct functionalization of inert C–H bonds is one of the most attractive yet challenging strategies for constructing molecules in organic chemistry. Herein, we disclose an unprecedented and Earth abundant Cu/Cr catalytic system in which unreactive alkyl C–H bonds are transformed into nucleophilic alkyl–Cr(III) species at room temperature, enabling carbonyl addition reactions with strong alkyl C–H bonds. Various aryl alkyl alcohols are furnished under mild reaction conditions even on a gram scale. Moreover, this new radical-to-polar crossover approach is further applied to the 1,1-difunctionalization of aldehydes with alkanes and different nucleophiles. Mechanistic investigations reveal that the aldehyde not only acts as a reactant but also serves as a photosensitizer to recycle the Cu and Cr catalysts.
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B. Wang, X. Zhang, Y. Cao, L. Zou, X. Qi, * Q. Lu* __________ _________________________________________________________________
This report describes the unprecedented electrooxidation of a solvent (e.g., DMF)-ligated B2cat2 complex, whereby a solvent-stabilized boryl radical is formed via quasi-homolytic cleavage of the B–B bond in a DMF-ligated B2cat2 radical cation. Cyclic voltammetry and density functional theory provide evidence to support this novel B–B bond activation strategy. Furthermore, a strategy for the electrochemical gem-diborylation of gem-bromides via paired electrolysis is developed for the first time, affording a range of versatile gem-diborylalkanes, which are widely used in synthetic society. Notably, this reaction approach is scalable, transition-metal-free, and requires no external activator.
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C. Huang, W. Ma, X. Zheng, M. Xu, X. Qi, * Q. Lu* ___________________________________________________________________________
Selective hydrogenation of
epoxides would be a direct and powerful approach for alcohol synthesis, but it
has proven to be elusive. Here, electrochemically epoxide hydrogenation using
electrons and protons as reductants is reported. A wide range of primary,
secondary, and tertiary alcohols can be achieved through selective Markovnikov
or anti-Markovnikov ring opening in the absence of transition metals.
Mechanistic investigations revealed that the regioselectivity is controlled by
the thermodynamic stabilities of the in situ generated benzyl radicals for
aryl-substituted epoxides and the kinetic tendency for Markovnikov selective
ring opening for alkyl-substituted epoxides.
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B. Wang#, P. Peng#, W. Ma, Z. Liu, C. Huang, Y. Cao, P. Hu, X. Qi, * Q. Lu* __________ _________________________________________________________________
Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby demonstrating the broad utility and functional-group tolerance of this protocol. Mechanistic studies disclosed that B2cat2 serves as both a reagent and a cathodic mediator, enabling electroreduction of difficult-to-reduce alkyl bromides or chlorides at a low potential.
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