- Selective Synthesis of Symmetrical Secondary Amines from Nitriles with a Pt?CuFe/Fe3O4 Catalyst and Ammonia Borane as Hydrogen Donor
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Hydrogenation of nitriles is an efficient and environmentally friendly route to synthesize symmetrical secondary amines, but it usually produces a mixture of amines, imines, and hydrogenolysis by-products. Herein we report a magnetic quaternary-component Pt?CuFe/Fe3O4 nanocatalyst system for the selective synthesis of symmetrical secondary amines with ammonia borane as hydrogen donor. The catalyst with a low Pt loading (0.456 wt%) is the source of the activity, and the d-band electron transfer from Cu to Fe enhances the selectivity. This synergistic effect results in the transformation of benzonitrile to dibenzylamine with excellent conversion (up to 99 %) and nearly quantitative selectivity (up to 96 %) under mild reaction conditions, nevertheless, the reaction TOF is as high as up to 1409.9 h?1. A variety of nitriles are suitable for the synthesis of symmetrical secondary amines. More importantly, unwanted hydrogenolysis byproducts, especially toluene, is not detected at all. In addition, the catalyst is magnetically recoverable, and it can be reused up to five times.
- Ai, Yongjian,Guo, Rongxiu,He, GuangQi,Hu, Ze-nan,Liang, Qionglin,Liu, Lei,Niu, Dun,Sun, Hong-bin,Tian, Haimeng,Zhang, Xinyue
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p. 1783 - 1788
(2020/09/02)
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- A ppm level Rh-based composite as an ecofriendly catalyst for transfer hydrogenation of nitriles: Triple guarantee of selectivity for primary amines
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Hydrogenation of nitriles to afford amines under mild conditions is a challenging task with an inexpensive heterogeneous catalyst, and it is even more difficult to obtain primary amines selectively because of the accompanying self-coupling side reactions. An efficient catalytic system was designed as Fe3O4@nSiO2-NH2-RhCu@mSiO2 to prepare primary amines through the transfer hydrogenation of nitrile compounds with economical HCOOH as the hydrogen donor. The loading of rhodium in the catalyst could be at the ppm level, and the TOF reaches 6803 h-1 for Rh. This catalytic system has a wide substrate range including some nitriles that could not proceed in the previous literature. The experimental results demonstrate that the excellent selectivity for primary amines is guaranteed by three tactics, which are the strong active site, the inhibition of side products by the hydrogen source and the special pore structure of the catalyst. In addition, the catalyst could be reused ten times without activity loss through convenient magnetic recovery.
- Liu, Lei,Li, Jifan,Ai, Yongjian,Liu, Yuhong,Xiong, Jialiang,Wang, Hongdong,Qiao, Yijun,Liu, Wenrui,Tan, Shanchao,Feng, Shaofei,Wang, Kunpeng,Sun, Hongbin,Liang, Qionglin
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p. 1390 - 1395
(2019/03/26)
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- Fentanyl analogue and application thereof
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The invention discloses a fentanyl analogue and application thereof. A general structural formula of a compound is as follows (described in the following description), wherein R1 is a hydrogen group,a methyl group, a hydroxyl group, a methoxyl group, a halogen and a cyano group, and R2 is a phenyl group, a benzyl group and 3,5-benzyldimethyl. The compound provided by the invention embodies the activating effect of a mu-opioid receptor and the recruitment function of weak beta-arrestin 2, and therefore, the compound can be used as an analgesic drug and can overcome the respiration inhibition effect caused by activating a beta-arrestin 2 signal pathway.
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Paragraph 0048; 0049
(2018/10/04)
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- Structure-activity relationship among purpurinimides and bacteriopurpurinimides: Trifluoromethyl substituent enhanced the photosensitizing efficacy
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At similar lipophilicity, compared to the nonfluorinated purpurinimide 11, the corresponding fluorinated analog 8 with a trifluoromethyl substituent at the lower half (position-132) of the molecule showed enhanced photosensitizing efficacy. The structural parameters established in purpurinimides (λmax: 700 nm) were successfully translated to the bacteriopurpurin imide system 19 (λmax: 792 nm) and within both series, a monotonic relationship between the lipophilicity and the in vivo PDT activity was observed. For preparing water-soluble compounds, the photosensitizers 8 and 19 were converted into the corresponding aminobenzyldiethylenetriamine pentaacetate conjugates 23 and 26. Acid treatment of purpurinimide 23 produced the corresponding water-soluble analog 24. Bacteriochlorin 26 under acidic or basic conditions mainly gave the decomposition products. At similar in vivo treatment conditions (C3H mice with RIF tumors and BALB-C mice with colon-26 tumors) the water-soluble purpurinimide 24 was found to be more effective than the methyl ester analog 8. These results suggest that besides overall lipophilicity the inherent charge of the photosensitizer also influences the PDT efficacy.
- Gryshuk, Amy,Chen, Yihui,Goswami, Lalit N.,Pandey, Suresh,Missert, Joseph R.,Ohulchanskyy, Tymish,Potter, William,Prasad, Paras N.,Oseroff, Allan,Pandey, Ravindra K.
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p. 1754 - 1767
(2008/02/03)
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- Sequential O- and N-acylation protocol for high-yield preparation and modification of rotaxanes: Synthesis, functionalization, structure, and intercomponent interaction of rotaxanes
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A pseudorotaxane consisting of a 24-membered crown ether and secondary ammonium salt with the hydroxy group at the terminus was quantitatively acylated by bulky acid anhydride in the presence of tributylphosphane as catalyst to afford the corresponding rotaxane in high yield. Large-scale synthesis without chromatographic separation was easily achieved. The ammonium group in the resulting rotaxane was quantitatively acylated with excess electrophile in the presence of excess trialkylamine. Various N-functionalized rotaxanes were prepared by this sequential double-acylation protocol. 1H NMR spectra and X-ray crystallographic analyses of the rotaxanes showed that the crown ether component was captured on the ammonium group in ammonium-type rotaxane by strong hydrogen-bonding intercomponent interaction. The conformation around the ammonium group was fixed by the hydrogen-bonding interaction. Meanwhile, the conformation of the amide-type rotaxane was determined by the weak CH/π interaction between the methylene group in crown ether and the benzene ring of the axle component. The N-acylation of ammonium-type rotaxane is useful for the preparation of both functionalized rotaxanes and weak intercomponent interaction-based rotaxanes.
- Tachibana, Yuya,Kawasaki, Hiroaki,Kihara, Nobuhiro,Takata, Toshikazu
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p. 5093 - 5104
(2007/10/03)
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