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9 results on '"Cao, Ke-Gong"'

5. Photocatalytic carboxylation of styrenes with CO2viaC=C double bond cleavage

Author

Cao, Ke-Gong, Gao, Tian-Yu, Liao, Li-Li, Ran, Chuan-Kun, Jiang, Yuan-Xu, Zhang, Wei, Zhou, Qi, Ye, Jian-Heng, Lan, Yu, and Yu, Da-Gang

Abstract

Catalytic cleavage of C=C double bonds in alkenes is highly important to convert feedstocks into high-value compounds. However, these approaches are mainly limited to oxidative cleavage of alkenes with excess oxidants and redox-neutral alkene metathesis. In contrast, reductive C=C double bond cleavage and functionalization have not been reported. Herein, we report a novel visible-light photoredox-catalyzed carboxylation of styrenes with CO2viareductive C=C double bond cleavage. The use of dicyclohexylmethylamine as scission reagent is the key to the success. Different from previous homologation reactions with CO2, this protocol enabled exchange of the carbon of styrenes with CO2, affording important aryl acetic acids viaC=C double bond cleavage. Moreover, preliminary mechanistic investigation and DFT calculations shed light on the reaction mechanism, disclosing aminomethyl-carboxylation intermediate, benzylic radicals and carbanions as key intermediates in the reaction.

Published
2024
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8. [Seminal parameters at different times of reanalysis of the normal semen samples detected in initial examination and their correlation with sperm DNA damage]

Author

Feng, Pan, Zhi-Peng, Xu, Liang, Shi, Zeng, He, Cao-Ke, Gong, Yu-Tian, Dai, and Lian-Jun, Pan

Subjects
Adult, Male, Semen Analysis, Young Adult, Fertility, Sperm Count, Sperm Motility, Humans, DNA Fragmentation, Diagnosis, Computer-Assisted, Middle Aged, Spermatozoa, DNA Damage
Abstract

To investigate the differences in semen quality at different times of reanalysis and the correlation of sperm DNA fragmentation index (DFI) with sperm motility alteration using semen samples completely liquefied and normal in initial examination.We analyzed 127 semen samples up to the inclusion criteria with the computer-assisted semen analysis (CASA) system at 15, 30 and 60 min after semen collection, and obtained sperm morphology parameters and DFI by Shorr staining and acridine orange test (AOT) , respectively.Sperm concentration, and the percentages of grades a and b sperm showed no statistically significant differences at the three time points (P0.05). The percentages of grades a + b and a + b + c sperm were significantly higher at 15 min than at 30 and 60 min after semen collection (P0.05), but with no significant difference between the latter two time points (P0.05). The incidence of alternation from normal to abnormal in at least one index of sperm motility at different times was 25.2%, but there were no significant differences in sperm DFI and morphology between the normal and abnormal groups (P0.05). Among the altered parameters of sperm motility from 15 to 60 min, the percentages of grades a, a + b and a + b + c sperm were all positively correlated with sperm DFI (P0.05).Semen samples completely liquefied within 15 min after collection and normal in initial examination, when reanalyzed at 30 and 60 min, showed significant decreases in the percentages of grades a + b and a + b + c sperm, but not in the percentages of grades a and b sperm, and the parameters of sperm motility might be abnormal. Thus, at least 2 sperm analyses are required for a comprehensive evaluation of fertility. Significant difference between the results of the two analyses, and particularly a markedly reduced percentage of rapidly progressive sperm, might indicate sperm DNA damage, and thus the necessity of sperm DNA damage detection.

Published
2013

9. Electrochemical Ring-Opening Dicarboxylation of Strained Carbon-Carbon Single Bonds with CO 2 : Facile Synthesis of Diacids and Derivatization into Polyesters.

Author

Liao LL, Wang ZH, Cao KG, Sun GQ, Zhang W, Ran CK, Li Y, Chen L, Cao GM, and Yu DG

Abstract

Diacids are important monomers in the polymer industry to construct valuable materials. Dicarboxylation of unsaturated bonds, such as alkenes and alkynes, with CO 2 has been demonstrated as a promising synthetic method. However, dicarboxylation of C─C single bonds with CO 2 has rarely been investigated. Herein we report a novel electrochemical ring-opening dicarboxylation of C─C single bonds in strained rings with CO 2 . Structurally diverse glutaric acid and adipic acid derivatives were synthesized from substituted cyclopropanes and cyclobutanes in moderate to high yields. In contrast to oxidative ring openings, this is also the first realization of an electroreductive ring-opening reaction of strained rings, including commercialized ones. Control experiments suggested that radical anions and carbanions might be the key intermediates in this reaction. Moreover, this process features high step and atom economy, mild reaction conditions (1 atm, room temperature), good chemoselectivity and functional group tolerance, low electrolyte concentration, and easy derivatization of the products. Furthermore, we conducted polymerization of the corresponding diesters with diols to obtain a potential UV-shielding material with a self-healing function and a fluorine-containing polyester, whose performance tests showed promising applications.

Published
2022
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