- Highly potent and stable capped siRNAs with picomolar activity for RNA interference
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Put a cap on it: Hairpin-shaped RNAs and dumbbell-shaped RNAs were prepared using a thiol-maleimino Michael addition and exhibited good serum and thermal stability. These capped structures were shown to be cleaved by Dicer and RNA interference (RNAi) experiments showed that RhpRNA (see picture, top right) was highly efficient at RNAi with an IC50 value of 6 pM. Copyright
- Wei, Lv,Cao, Liqiang,Xi, Zhen
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- Hydrolytic degradation of N,N′-ethylenedimaleimide: Crystal structures of key intermediates and proposed mechanisms
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Maleimide groups are used extensively in bioconjugation reactions, but limited mechanistic studies are available regarding their hydrolysis reactions. In this paper, five single-crystal structures related with the reaction of four-step hydrolytic degradation of N,N′-ethylenedimaleimide have been investigated. On the basis of experimental results, the reaction mechanisms without or with water catalysis are proposed, which could provide some enlightenment into the study of similar hydrolytic degradations.
- Tan, Xue-Jie,Cheng, Shuang-Shuang,Shi, Yan,Xing, Dian-Xiang,Liu, Yun,Li, Hui,Feng, Wen-Quan,Yang, Jian-Bo
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Read Online
- Preparation method of bismaleimide alkyl compound
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The invention provides a preparation method of a bismaleimide alkyl compound, comprising the following steps of: S1. carrying out ring-opening reaction on cis-butadiene maleic anhydride and a diaminoalkyl compound in a first solvent to obtain an intermediate; and S2, carrying out a ring closing reaction on the intermediate in a second solvent in the presence of an organic alkali to obtain the bismaleimide alkyl compound. According to the preparation method of the bismaleimide alkyl compound disclosed by the embodiment of the invention, the cheap raw materials of maleic anhydride and diaminoalkyl compound are used as the raw materials, and the whole operation avoids long-time high-temperature reaction and reduces the production cost; besides, the trouble of column passing is avoided through later purification, the yield is greatly increased while operation is convenient, and the method is suitable for industrial production and has a good application prospect.
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Paragraph 0060; 0066-0071; 0075-0077
(2020/09/23)
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- Nickel(II) Tetraphenylporphyrin as an Efficient Photocatalyst Featuring Visible Light Promoted Dual Redox Activities
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Nickel(II) tetraphenylporphyrin (NiTPP) is presented as a robust, cost-effective and efficient visible light induced photoredox catalyst. The ground state electrochemical data (CV) and electronic absorption (UV-Vis) spectra reveal the excited state redox potentials for [NiTPP]*/[NiTPP].? and NiTPP].+/[NiTPP]* couples as +1.17 V and ?1.57 V vs SCE respectively. The potential values represent NiTPP as a more potent photocatalyst compare to the well-explored [Ru(bpy)3]2+. The non-precious photocatalyst exhibits excited state redox reactions in dual fashions, i. e., it is capable of undergoing both oxidative as well as reductive quenching pathways. Such versatility of a photocatalyst based on first-row transition metals is very scarce. This unique phenomenon allows one to perform diverse types of redox reactions by employing a single catalyst. Two different sets of chemical reactions have been performed to represent the synthetic utility. The catalyst showed superior efficiency in both carbon-carbon and carbon-heteroatom bond-forming reactions. Thus, we believe that NiTPP is a valuable addition to the photocatalyst library and this study will lead to more practical synthetic applications of earth-abundant-metal-based photoredox catalysts. (Figure presented.).
- Mandal, Tanumoy,Das, Sanju,De Sarkar, Suman
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supporting information
p. 3200 - 3209
(2019/05/16)
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- Cp?Co(III)-Catalyzed C-H Alkylation with Maleimides Using Weakly Coordinating Carbonyl Directing Groups
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A novel protocol for ortho-C-H alkylation of aromatic and heteroaromatic ketones and esters under Cp?Co(III) catalysis has been developed for the first time. The reaction proceeds through initial cyclometalation via weak chelation-assisted C-H bond activation, followed by coordination of activated alkene, insertion between Co-C, and protodemetalation.
- Mandal, Rajib,Emayavaramban, Balakumar,Sundararaju, Basker
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supporting information
p. 2835 - 2838
(2018/05/29)
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- An efficient reverse Diels-Alder approach for the synthesis of N-alkyl bismaleimides
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Bismaleimides are useful precursors for Diels-Alder reactions, Michael additions, and thiol-maleimide based conjugation for the synthesis of materials and polymers. Use of bismaleimide cross linkers for generating polymers, bioconjugate molecules, and useful imaging molecules is an active area of research. An efficient and practical synthetic protocol for N-alkyl bis-maleimide cross linkers starting from furan protected maleimide employing a reverse Diels-Alder reaction is reported.
- Rao, Venkataramanarao,Navath, Suryakiran,Kottur, Mohankumar,McElhanon, James R.,McGrath, Dominic V.
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p. 5011 - 5013
(2013/09/02)
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- A New Class of Bradykinin Antagonists: Synthesis and in Vitro Activity of Bissuccinimidoalkane Peptide Dimers
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A systematic study on the dimerization of the bradykinin (BK) antagonist D-Arg0-Arg1-Pro2-Hyp3-Gly4-Phe5-Ser6-D-Phe7-Leu8-Arg9 has been performed.The first part of this study involved compounds wherein dimerization was carried out by sequentially replacing each amino acid with cysteine and cross-linking with bismaleimidohexane.The second part of this study utilized a series of bissuccinimidoalkane dimers wherein the intervening methylene chain was varied systematically from n = 2 to n = 12 while the point of dimerization was held constant at position 6.The biological activities of these dimers were then evaluated on BK-induced smooth muscle contraction in two different isolated tissue preparations: guinea pig ileum (GPI) and rat uterus (RU).Several of the dimeric BK antagonists displayed remarkable activites and long durations of action.In addition, dimerization at position 4, 7, 8, or 9 produced dimeric analogues with markedly reduced potency.Rank order of antagonist potency as a function of dimerization position is as follows: rat uterus, 6 > 5 > 0 > 2 > 1 >3 >> 4, 7, 8, 9; guinea pig ileum, 6 > 5 > 3 > 2 > 1 > 0 >> 4, 7, 8, 9.Evaluation of the linker length as represented by the number of methylene units indicated an optimal distance between the two monomeric peptides of six to eight methylene moieties.These studies also revealed that the carbon-chain length significantly affected the duration of action in vitro and resulted in partial agonism effects when n > 8.The optimum activity in vitro was achieved with dimerization at position 6 and n = 6 (designated herein as compound 25; alternatively, CP-0127).Similar effects in potency were also seen when the monomeric antagonist D-Arg0-Arg1-Pro2-Hyp3-Gly4-Phe5-Ser6-D-Phe7-Phe8-Arg9 (NPC-567) was dimerized using similar chemistry.These results suggest that the development of BK antagonists of significant therapeutic potential may be possible using a dimerization strategy that can overcome the heretofore limiting problems of potency and in vivo duration of action found with many of the BK antagonists in the literature.
- Cheronis, John C.,Whalley, Eric T.,Nguyen, Khe T.,Eubanks, Shad R.,Allen, Lisa G.,et al.
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p. 1563 - 1572
(2007/10/02)
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- Curable mixtures based on maleimides and propenyl-substituted phenols, and the use thereof
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Curable mixtures of (a) maleimides of the general formula I STR1 wherein R is an n-valent aliphatic or aromatic radical, and n is the number 1, 2 or 3; and (b) mono- or polyvalent phenols which contain in the molecule at least one 1-propenyl group in the ortho- or para-position with respect to the hydroxyl group, or isomeric mixtures of mono- or polyvalent phenols which are propenyl-substituted in the ortho- or para-position and mono- or polyvalent phenols which are allyl-substituted in the ortho- or para-position, the proportion of propenyl groups in the isomeric mixture having to be at least 5 equivalent-%, relative to the sum of the equivalents of propenyl and allyl groups. The novel mixtures cure at elevated temperatures relatively rapidly, and produce molded materials having valuable mechanical properties.
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