- Boryl Radical Activation of Benzylic C-OH Bond: Cross-Electrophile Coupling of Free Alcohols and CO2via Photoredox Catalysis
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A new strategy for the direct cleavage of the C(sp3)-OH bond has been developed via activation of free alcohols with neutral diphenyl boryl radical generated from sodium tetraphenylborate under mild visible light photoredox conditions. This strategy has been verified by cross-electrophile coupling of free alcohols and carbon dioxide for the synthesis of carboxylic acids. Direct transformation of a range of primary, secondary, and tertiary benzyl alcohols to acids has been achieved. Control experiments and computational studies indicate that activation of alcohols with neutral boryl radical undergoes homolysis of the C(sp3)-OH bond, generating alkyl radicals. After reducing the alkyl radical into carbon anion under photoredox conditions, the following carboxylation with CO2 affords the coupling product.
- Jiang, Yi-Qian,Lan, Yu,Li, Shi-Jun,Li, Wen-Duo,Li, Yan-Lin,Wu, Yang,Xia, Ji-Bao
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- Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)?F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass.
- Bo, Zhi-Yu,Chen, Lin,Gao, Tian-Yu,Jing, Ke,Lan, Yu,Liu, Shi-Han,Luo, Shu-Ping,Yan, Si-Shun,Yu, Bo,Yu, Da-Gang
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supporting information
p. 3099 - 3113
(2021/11/16)
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- CYCLIC AMINE COMPOUND
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An object of the present invention is to provide a cyclic amine compound which has a potent inhibitory effect on the binding of a2C-adrenoceptor and is useful in preventing and treating disorders attributable to a2C-adrenoceptor.The above-described object is solved by the following cyclic amine compound, etc., wherein X is O, S, SO, SO2 or NR2, etc.; R1 is a hydrogen atom, a cyano group, a carboxyl group, a C2-C13 alkoxycarbonyl group, a carbamoyl group, etc.; Ar1 and Ar2 are the same or different and each represent an aryl or heteroaryl group which may be substituted by 1 to 3 substituents and so on; ring B is a benzene ring may be substituted by 1 to 3 substituents and so on; n is an integer from 1 to 10; and p and q are the same or different and each represent an integer of 1 or 2.
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Page/Page column 20
(2008/06/13)
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