A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition m...A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .展开更多
A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is re...A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.展开更多
The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-...The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.展开更多
Methyl, ethyl, n-propyl, and benzyl p-hydroxyphenyl ketones and 6-hydroxy-1-tetralone are shown under the condition of ethylene ketal formation to undergo alkyl-carbonyl C-C bondscission, but not with p-hydroxybenzoph...Methyl, ethyl, n-propyl, and benzyl p-hydroxyphenyl ketones and 6-hydroxy-1-tetralone are shown under the condition of ethylene ketal formation to undergo alkyl-carbonyl C-C bondscission, but not with p-hydroxybenzophenone, p-hydroxyisobutyrophenone, and 5-hydroxy-1-indanone. It is suggested that the scissiou is preceded by an aldol condensation.展开更多
3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formati...3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.展开更多
Over the past 20 years, small molecule solid phase synthesis has become a powerful tool in the discovery of novel molecular materials. In the development of organic chemistry, the carbon-carbon bond formation has alwa...Over the past 20 years, small molecule solid phase synthesis has become a powerful tool in the discovery of novel molecular materials. In the development of organic chemistry, the carbon-carbon bond formation has always been one of the most useful and fundamental reaction. The current review summarizes recent developments in metal-catalyzed coupling reactions. The following method is discussed in detail—the cross-coupling of aryl halides with aryl boronic acids (the Suzuki coupling), and the others C-C bond formation reactions as the palladium-catalyzed reaction between an aryl and (or) alkyl halide and a vinyl functionality (the Heck reaction);and the palladium-catalyzed cross-coupling reaction of organostannyl reagents with a variety of organic electrophiles (the Stille reaction)—are mentioned.展开更多
Each possible pair of residues inβ-1,4 glucanase for disulfide formation was assessed using online websites,and four pairs L28C-S256C,Q41C-P278C,S122C-N163C and A184C-A215C were selected.Accordingly,four recombinant ...Each possible pair of residues inβ-1,4 glucanase for disulfide formation was assessed using online websites,and four pairs L28C-S256C,Q41C-P278C,S122C-N163C and A184C-A215C were selected.Accordingly,four recombinant plasmids pET28a(+)EccslH28,pET28a(+)EccslH41,pET28a(+)EccslH122 and pET28a(+)EccslH184 were prepared and transformed into E.coli to express the recombinant enzymes.Then analysis on enzymatic properties showed that T50 of the recombinant enzymes was increased from 10 min for EccslHt2 to 90 min for EccslH28 and 40 min for EccslH41 at 70℃,while their optimum pH value and pH stability were not affected,which proved that the introduction of disulfide bond improved the thermal stability ofβ-1,4 glucanase.展开更多
文摘A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .
基金the National Natural Science Foundation of China (No. 29772012)
文摘A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.
基金financially supported by the National Natural Science Foundation of China(21972099)the Application Foundation Program of Sichuan Province(2021YJ0305)+1 种基金the 111 project(B17030).Shanghai Synchrotron Radiation Facility(SSRF)for XAS experiments and the support by the project from NPL of CAEP(2019BB08)。
文摘The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.
文摘Methyl, ethyl, n-propyl, and benzyl p-hydroxyphenyl ketones and 6-hydroxy-1-tetralone are shown under the condition of ethylene ketal formation to undergo alkyl-carbonyl C-C bondscission, but not with p-hydroxybenzophenone, p-hydroxyisobutyrophenone, and 5-hydroxy-1-indanone. It is suggested that the scissiou is preceded by an aldol condensation.
文摘3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.
基金gratefully acknowledged for the financial support of the Polish National Centre of Progress of Explorations Grant no.NR05-0017-10/2010 and Wroclaw University of Technology.
文摘Over the past 20 years, small molecule solid phase synthesis has become a powerful tool in the discovery of novel molecular materials. In the development of organic chemistry, the carbon-carbon bond formation has always been one of the most useful and fundamental reaction. The current review summarizes recent developments in metal-catalyzed coupling reactions. The following method is discussed in detail—the cross-coupling of aryl halides with aryl boronic acids (the Suzuki coupling), and the others C-C bond formation reactions as the palladium-catalyzed reaction between an aryl and (or) alkyl halide and a vinyl functionality (the Heck reaction);and the palladium-catalyzed cross-coupling reaction of organostannyl reagents with a variety of organic electrophiles (the Stille reaction)—are mentioned.
基金Supported by the National Key Research and Development Plan of China(2019YFC1905902,2019YFC1905900)Key Research and Development Plan in Shandong Province(2020CXGC010603,2021ZDSYS10,2022CXGC020206)+2 种基金"Open Competition Mechanism"Project of Qilu University of Technology(Shandong Academy of Sciences)(2022JBZ01-06)Taishan Industry Leading Talent Program(tscy20180103)National Natural Science Foundation of China(31801527)。
文摘Each possible pair of residues inβ-1,4 glucanase for disulfide formation was assessed using online websites,and four pairs L28C-S256C,Q41C-P278C,S122C-N163C and A184C-A215C were selected.Accordingly,four recombinant plasmids pET28a(+)EccslH28,pET28a(+)EccslH41,pET28a(+)EccslH122 and pET28a(+)EccslH184 were prepared and transformed into E.coli to express the recombinant enzymes.Then analysis on enzymatic properties showed that T50 of the recombinant enzymes was increased from 10 min for EccslHt2 to 90 min for EccslH28 and 40 min for EccslH41 at 70℃,while their optimum pH value and pH stability were not affected,which proved that the introduction of disulfide bond improved the thermal stability ofβ-1,4 glucanase.
