Tuning the Hemolytic and Antibacterial Activities of Amphiphilic Polynorbornene Derivatives
摘要:
Amphiphilic cationic polynorbomene derivatives, soluble in water, were prepared from modular norbomene monomers, with a wide range of molecular weights (M-n = 1600-137 500 g/mol) and narrow polydispersities (PDI = 1.1-1.3). The antibacterial activity determined by growth inhibition assays and the hemolytic activity against human red blood cells were measured and compared to determine the selectivity of the polymers for bacterial over mammalian cells. The effects of monomer repeat unit hydrophobicity and polymer molecular weight on antibacterial and hemolytic activities were determined. The hydrophobicity of the repeat unit was observed to have dramatic effects on antibacterial and hemolytic activities. Lipid membrane disruption activities of the polymers was confirmed by measuring polymer-induced dye leakage from large unilamellar vesicles. By tuning the overall hydrophobicity of the polymer through random copolymerizations of modular norbomene derivatives, highly selective, nonhemolytic antibacterial activities were obtained. For appropriate monomer composition, selectivity against bacteria versus human red blood cells was determined to be over 100.
benzyl-substituted cyclopentadienyltitaniumcomplex 26 may be spontaneously converted into metallocyclic complex 19. The position of the MeO group on the benzene ring is the key factor to the cyclization. In the case of meta- and para-MeO benzyl-substituted titaniumcomplexes 23 and 25, there was no possibility to form a titanoxacycle complex, such as 19, because the MeO group is too far from titanium. A probable
已经合成了二十八个新的苄基取代的环戊二烯基钛配合物。其中,通过X射线分析研究了五个典型的分子结构。发现在制备含邻-MeO的苄基取代的钛络合物时,当苄基碳原子上的两个取代基都为Et或更大的基团时,总是形成钛氧环络合物。卤化物的存在促进了环化反应。卤化物对于环化的活性顺序为:LiI-NaI> LiBr-Br 2 > NaBr-KI> KBr> I 2。高温有利于环化。在80°C下,正常的邻-MeO苄基取代的环戊二烯基钛络合物26可以自发地转化成金属环配合物19。MeO基团在苯环上的位置是环化的关键因素。在间-和对-MeO苄基取代的钛配合物23和25的情况下,由于MeO基团距离钛太远,因此不可能形成钛氧杂环丙烷配合物,例如19。提出了一种可能的涉及四元过渡态的机制。
A Flow Microreactor Approach to a Highly Efficient Diels–Alder Reaction with an Electrogenerated o-Quinone
作者:Kenta Tanaka、Hirona Yoshizawa、Mahito Atobe
DOI:10.1055/s-0037-1611725
日期:2019.6
reaction of an o-quinone generated in an electrochemicalflowmicroreactor. In the flowmicroreactor system, 4-tert-butyl-o-benzoquinone was easily electrogenerated from 4-tert-butylpyrocatechol in the absence of chemical oxidants and then rapidly used, without decomposing, in a subsequent Diels–Adler reaction with various fulvenes to give the desired products efficiently.
Highly regioselective electrophilic substitution of fulvenes with ethyl glyoxylate, catalyzed by EtAlCl2 or Yb(OTf)3 was achieved. Subsequent Diels–Alder reaction of the adduct with various dienophiles provides an efficient protocol toward highly functionalized indane and tricyclo[5.2.1.02,6]dec-8-ene systems.
Regioselective and stereoselective inverse-electron-demand Diels-Alder reaction of N-sulfonyl-1-aza-1,3-butadiene with fulvenes are described. The methodology provides an efficient and novel route to tetrahydro-[1]pyrindine systems.
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