Introduction
C-H key and CO2 direct carboxylation base is a kind of Attractive strategies can synthesize the valuable carboxylic acid of high -level atom, high -level, and oxidation and restoration economy.Although there have been great progress in this field, because the uncle C (SP3) -H keys inertia and significant spatial resistance, catalytic carcinization is still a challenge.Based on this, Professor Yu Dagang (correspondent) and others of Sichuan University reported that the ospper-based C (SP3) -H and CO2 directly carboxyized by visible light oxidation and catalytic catalytic.Various all -carbon percug acids (ACQCAS), which is of great significance in pharmaceutical chemistry, is successfully prepared at high income.This direct carboxyl is characterized by good functional group tolerance, wide range of substrates, and mild operating conditions.
In addition, this method can compose key drugs or biological active molecules efficiently and quickly, such The target carboxylic acid directional ability promotes the various functionalization of the C (SP2) -H key, which highlights its practical application.Mechanism research shows that carbon ions, as a key intermediate reaction to CO2, are generated by continuous light -induced electron transfer process and generated through a single electronics.
Related work is "Visible-Light PhotoreDox-Catalyzed Direct Carboxylation of Tertiary C (SP3) of all -Carbon Quaternary Carboxylic Acids was published in "Journal of the American Chemical Society".
Dr. Yu Dagang , born in September 1986, graduated from the School of Chemistry, Sichuan University in 2007.07; Dr. 2012.07 graduated from the School of Chemistry and Molecular Engineering at Peking University; 2012.10 —2014.12 Postdoctoral research at the University of Minister, Germany, scholar of Humboldt; 2015.01 (28 years old) became a professor/doctoral supervisor at the School of Chemistry of Sichuan University; Outstanding Youth Fund of the National Natural Science Foundation of China in 2018; Outstanding of the National Natural Science Foundation of China in 2022 Youth Fund. Research direction : carbon dioxide use, free radical chemistry (visible optical chemistry, electrochemical), cheap metal catalysis.
For details Strong> graphic interpretation
Under the condition of the response temperature of 60 ° C, under the normal pressure of CO2, 2, 4, 5, 6 -The (9H-Kagazazo) benzene (4czipn) is used as a photocatalyst (PC), and Cysh (CYSH) is a catalyst. Pivocs is alkaline. /Strong> Consonomization of C (SP3) -H key in catalytic carboxylation.Through systematically screening reaction conditions, including alkali, solvents, temperature, and PC quantity, standard reaction conditions are determined: 1 (0.2 mmol, 1 equivalent), 4czipn (10 mol%), CYSH (CYSH (CYSH (CYSH (CYSH (CYSH (CYSH (CYSH 20 mol%), Pivocs (2nd equivalent), DMF (1.5 ml), reactoring for 24 hours in the atmosphere of 60 ° C, 30 W blue light, and CO2 at the reaction temperature, and the separation rate was given after 2 n HCL.
Figure 1. Use CO2 carboxylation to synthesize ACQCAS
Table 1. Optimization of reaction conditions
Table 2. Delivery expansion
Figure 2. Synthetic functional organic molecules
Through mechanism research to clarify the mechanism of C (SP3) -H and CO2 carboxylization.In the free radical suppression experiment, add 2, 2, 6, 6, 6, and tetraramine oxides (TEMPO) as a free radical cleaner in the standard system. > And 13 , and quantitative recycling start materials.The results show that free radical intermediates may be involved in this process, and sulmiol and pivocs play a vital role in the catalytic cycle.Add 10 equivalent D2O to the reaction mixture, you can get a crickets D -11 , the yield is 80%, and the income rate is 24%, which indicates that it means Phenyl carbon ions may be formed during this conversion process.The quenching experiment was used in DMF to use saturated PIVOCS. It was found that the addition of CYSH has not significantly impact on the hacity, indicating that Pivocs plays a key role in hacked optical excitement (PC*).
Figure 3. Mechanical research
The author proposes one Possible catalytic cycle mechanism: First of all, PC* i was caught by pivocs, and then decarcar to generate TBU free radical II and reducing optical catalysts (PC −) III .The TBU free radicals II were then quenched by sulfenol to generate a radical free radical IV .The radical radical IV then reacts with the substrate 1 to generate uncle -based carbon free radicals v and regenerate the 巯 base.Uncle 由 由 V has a larger negative reduction potential, and then is PC • − The highly restored PC • −* Species vi restore.This Conpet process leads to the formation of the key carbon intermediate VII .Finally, a nuclear attack on CO2 and a mass response to the quality of the ACQCAS 2 required.
Figure 4. Possible mechanisms
Visible-Light PhotoreDox-Catalyzed Direct Carboxylation of Tertiary C (SP3) -H Bonds with CO2: Facile Synthesis of All-CARBON Quaternary Acids.j. Chem. Soc., 2024 , https: // doi .org/10.1021/JACS.4C09558.
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