The reaction of[CpMo(CO)_2]_2 with 8,8'-diquinolyl disulphide C_9H_6NSSNC_9H_6 resulted in the cleavage of Mo≡Mo triple bond to give a new nononuclear complex CpMo(CO)_2(N,S-C_9H_6NS)which was refluxed with PPh_3...The reaction of[CpMo(CO)_2]_2 with 8,8'-diquinolyl disulphide C_9H_6NSSNC_9H_6 resulted in the cleavage of Mo≡Mo triple bond to give a new nononuclear complex CpMo(CO)_2(N,S-C_9H_6NS)which was refluxed with PPh_3 in THF to form the title complex.The crystal structure of the title complex was determined by X-ray diffraction.展开更多
5-Substituted-4-animo-3-thiol-l,2,4-triazoles (1a—b) react with ortho nitrochloro-benzene or para-nitrochlorobenzene to give N—N bond cleavage products 2a—d, one structure of which (2b) has been unambiguously confi...5-Substituted-4-animo-3-thiol-l,2,4-triazoles (1a—b) react with ortho nitrochloro-benzene or para-nitrochlorobenzene to give N—N bond cleavage products 2a—d, one structure of which (2b) has been unambiguously confirmed by an X-ray structural analysis.展开更多
Herein, two efficient palladium-catalyzed intermolecular oxidative coupling reactions of (Z)-enamines with isocyanides via selective β-C(sp2)-H and/or C=C bond cleavage have been developed, leading to controllabl...Herein, two efficient palladium-catalyzed intermolecular oxidative coupling reactions of (Z)-enamines with isocyanides via selective β-C(sp2)-H and/or C=C bond cleavage have been developed, leading to controllable chemodivergent and stereoselective construction of a wide range of (E)-β-carbamoylenamine derivatives containing strong intramolecular hydrogen bonds. Furthermore, possible reaction pathways for these transfor- mations are proposed on the basis of preliminary mechanism studies.展开更多
The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new meth...The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new methods for generating alkoxy radical species have emerged.These newly developed methods are mainly based on the photolysis by visible light under mild conditions,thus allowing for new transformations of the carbon-centered radical species that are generated from theβ-scission or hydrogen abstraction of the alkoxy radicals.展开更多
A deuterated methylthiolating reagent with a broad spectrum,designated as DMTp,has been ingeniously formulated.This new reagent can be produced with high efficiency through the simple combination of commercially avail...A deuterated methylthiolating reagent with a broad spectrum,designated as DMTp,has been ingeniously formulated.This new reagent can be produced with high efficiency through the simple combination of commercially available methyl 3-thiopropanoate and CD_(3)l.This novel SCD_(3) reagent exhibits excellent reactivity with electrophiles such as alkyl iodides,benzyl chlorides,aryl halides(l,Br)and aryl triflates,resulting in high levels of deuterium content(99%D).Representative deuterated methylthiolated biomolecules,such as Sulfoxaflor,havebeen synthesizedforuse in pharmaceutical discoveryand development.展开更多
The radical S-adenosyImethionine(SAM)enzyme NosL catalyzes the conversion of L-tryptophan((-Trp,1)to 3-methyl-2-indolic acid(MIA,2),a key in termediate in the biosynthesis of the peptide an tibiotic no siheptide.Previ...The radical S-adenosyImethionine(SAM)enzyme NosL catalyzes the conversion of L-tryptophan((-Trp,1)to 3-methyl-2-indolic acid(MIA,2),a key in termediate in the biosynthesis of the peptide an tibiotic no siheptide.Previous study showed that this remarkable recombination reaction starts from the cleavage of the Cα-COO^(-) bond to result in a·CO_(2)^(-) radical migration.In contrast to the radical SAM tyrosine lyases,NosL appears unable to cleave the Cα-Cβ bond,which is intrinsically more favorable to be cleaved than the Cα-COO^(-) bond.In this study,we investigate the NosL activity with tryptamine(11)and tryptophol(12),two L-Trp analogues lacking a carboxylate moiety.We showed that NosL cleaves the C1-C2 bond of these two substrates to produce 3-methylindole(7),suggesting that the enzyme can still catalyze a β-scission when the carboxyl group of Trp is absent.We also showed the enzyme exhibits a promiscuous activity,initiating the reaction by abstracting hydrogen atoms from two different sites to produce two sets of products.展开更多
To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettes in vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ri...To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettes in vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ribozyme embedded into the human snRNA U6, and detected the activity of the ribozyme in vitro and in vivo. Meanwhile we compared it with the self-cleaving hammerhead ribozymes that we previously studied, and with the general ribozyme, cloned into RNA polymerase II expression systems. The results showed that the three ribozymes, p1.5RZ107, pRZ107 and pU6RZ107 had the correct structure, and that they could cleave caspase-3 mRNA exactly to produce two fragments: 143nt/553nt. p1.5RZ107 has the highest cleavage efficiency in vitro, almost 80%. However, the U6 chimeric ribozyme, pU6RZ107, has the highest cleavage activity in vivo, almost to 65%, though it has lower cleavage activity in vitro. The cleavage results demonstrated that the pU6RZ107, the U6 chimeric ribozyme, could more efficiently express and downregulate the level of caspase-3 in vivo, and the ribozyme could provide an alternative approach to the research into the mechanism of apoptosis and human gene therapy also.展开更多
Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. In...Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. In various synthetic routes,[S,S-(E)]-3-(hydroxymethyl) oxiranebutanoic acid methyl ester (1) and (S)-5-(ben-zoyloxy)-6-oxohexanoic acid methyl ester (2) have been frequently used as the C-Cfragment of LTA3 and the C-Cfragment of LTB4, respectively. (Scheme1)展开更多
文摘The reaction of[CpMo(CO)_2]_2 with 8,8'-diquinolyl disulphide C_9H_6NSSNC_9H_6 resulted in the cleavage of Mo≡Mo triple bond to give a new nononuclear complex CpMo(CO)_2(N,S-C_9H_6NS)which was refluxed with PPh_3 in THF to form the title complex.The crystal structure of the title complex was determined by X-ray diffraction.
基金Project (No. 29802002) supported by the National Natural Science Foudation of China, the Natural Science Foundation of Hubei Province and the Dawn Plan of Science and Technology for Young Scientists of Wuhan City.
文摘5-Substituted-4-animo-3-thiol-l,2,4-triazoles (1a—b) react with ortho nitrochloro-benzene or para-nitrochlorobenzene to give N—N bond cleavage products 2a—d, one structure of which (2b) has been unambiguously confirmed by an X-ray structural analysis.
基金The authors thank the National Key Research and Development Program of China (2016YFA0602900) and the National Natural Science Foundation of China (21490572 and 21420102003) for financial support.
文摘Herein, two efficient palladium-catalyzed intermolecular oxidative coupling reactions of (Z)-enamines with isocyanides via selective β-C(sp2)-H and/or C=C bond cleavage have been developed, leading to controllable chemodivergent and stereoselective construction of a wide range of (E)-β-carbamoylenamine derivatives containing strong intramolecular hydrogen bonds. Furthermore, possible reaction pathways for these transfor- mations are proposed on the basis of preliminary mechanism studies.
基金The project is supported by NSFC(91956104),BNLMS,and Laboratory for Synthetic Chemistry and Chemical Biology of Health@InnoHK of ITC,HKSAR.
文摘The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s,but it has remained dormant for the past few decades.Recently,alkoxy radicals attract the attentions again,because new methods for generating alkoxy radical species have emerged.These newly developed methods are mainly based on the photolysis by visible light under mild conditions,thus allowing for new transformations of the carbon-centered radical species that are generated from theβ-scission or hydrogen abstraction of the alkoxy radicals.
基金financial support from the National Natural Science Foundation of China(22101005)the National Key Research and Development Program of China(2021YFD1700104)+1 种基金Key R&D Projects of Anhui Province(202104a06020008)Excellent Youth Program of Anhui Province(2022AH030095).
文摘A deuterated methylthiolating reagent with a broad spectrum,designated as DMTp,has been ingeniously formulated.This new reagent can be produced with high efficiency through the simple combination of commercially available methyl 3-thiopropanoate and CD_(3)l.This novel SCD_(3) reagent exhibits excellent reactivity with electrophiles such as alkyl iodides,benzyl chlorides,aryl halides(l,Br)and aryl triflates,resulting in high levels of deuterium content(99%D).Representative deuterated methylthiolated biomolecules,such as Sulfoxaflor,havebeen synthesizedforuse in pharmaceutical discoveryand development.
基金supported in part by grants from the National Key Research and Development Program(2018Y F A0900402 and 2016Y F A0501302)from the National Natural Science Foundation of China(21822703 and 21921003).
文摘The radical S-adenosyImethionine(SAM)enzyme NosL catalyzes the conversion of L-tryptophan((-Trp,1)to 3-methyl-2-indolic acid(MIA,2),a key in termediate in the biosynthesis of the peptide an tibiotic no siheptide.Previous study showed that this remarkable recombination reaction starts from the cleavage of the Cα-COO^(-) bond to result in a·CO_(2)^(-) radical migration.In contrast to the radical SAM tyrosine lyases,NosL appears unable to cleave the Cα-Cβ bond,which is intrinsically more favorable to be cleaved than the Cα-COO^(-) bond.In this study,we investigate the NosL activity with tryptamine(11)and tryptophol(12),two L-Trp analogues lacking a carboxylate moiety.We showed that NosL cleaves the C1-C2 bond of these two substrates to produce 3-methylindole(7),suggesting that the enzyme can still catalyze a β-scission when the carboxyl group of Trp is absent.We also showed the enzyme exhibits a promiscuous activity,initiating the reaction by abstracting hydrogen atoms from two different sites to produce two sets of products.
基金the High School Science Foundation of Shanghai (Grant No. 98QN60) and the Chinese Academy of Sciences (Grant No. KSCX2-2-04).
文摘To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettes in vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ribozyme embedded into the human snRNA U6, and detected the activity of the ribozyme in vitro and in vivo. Meanwhile we compared it with the self-cleaving hammerhead ribozymes that we previously studied, and with the general ribozyme, cloned into RNA polymerase II expression systems. The results showed that the three ribozymes, p1.5RZ107, pRZ107 and pU6RZ107 had the correct structure, and that they could cleave caspase-3 mRNA exactly to produce two fragments: 143nt/553nt. p1.5RZ107 has the highest cleavage efficiency in vitro, almost 80%. However, the U6 chimeric ribozyme, pU6RZ107, has the highest cleavage activity in vivo, almost to 65%, though it has lower cleavage activity in vitro. The cleavage results demonstrated that the pU6RZ107, the U6 chimeric ribozyme, could more efficiently express and downregulate the level of caspase-3 in vivo, and the ribozyme could provide an alternative approach to the research into the mechanism of apoptosis and human gene therapy also.
基金Project supported by the Chinese Academy of Sciences and the State Committee of Science and Technology of China.
文摘Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. In various synthetic routes,[S,S-(E)]-3-(hydroxymethyl) oxiranebutanoic acid methyl ester (1) and (S)-5-(ben-zoyloxy)-6-oxohexanoic acid methyl ester (2) have been frequently used as the C-Cfragment of LTA3 and the C-Cfragment of LTB4, respectively. (Scheme1)