- Quinizarin Derivatives as Photoinitiators for Free-Radical and Cationic Photopolymerizations in the Visible Spectral Range
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We report the use of efficient visible-light sensitive allyl (QA) and epoxidized (QE) quinizarin derivatives as photoinitiating systems when combined with an appropriate electron donor (methyldiethanol amine, MDEA), an electron acceptor (iodonium salt, Iod), or a H donor (thiol derivative), for free-radical photopolymerization (FRP), cationic photopolymerization (CP), and a thiol-ene process. These systems have demonstrated excellent initiating properties under air or in laminated conditions under visible-light irradiation (LEDs?405, 455, and 470 nm or Xe lamp) for FRP, CP, or the thiol-ene process and appear more efficient than the well-known camphorquinone-based photoinitiating systems. As highlighted by electron paramagnetic resonance (EPR) and laser flash photolysis experiments, QA (or QE) acts either as an electron donor via a photoinduced electron transfer pathway with Iod or as a proton/proton-coupled electron transfer promoter with MDEA or a thiol derivative. Two types of interpenetrated polymer networks have been synthesized either by CP and the thiol-ene process with di(ethylene glycol) divinyl ether/trithiol or by a concomitant free-radical and cationic photopolymerization with an epoxide/acrylate blend mixture upon LED?455 or 470 nm exposure. Interestingly, the resulting quinizarin-derived materials showed antiadherence properties under visible-light exposure even after two cycles of antibacterial experiments. Quinizarin derivatives can not only initiate photopolymerization but also generate singlet oxygen on the surface of the materials for preventing the adhesion and proliferation of bacteria under visible-light activation.
- Abbad-Andaloussi, Samir,Blacha-Grzechnik, Agata,Brezová, Vlasta,Jockusch, Steffen,Malval, Jean-Pierre,Rivard, Michael,Sautrot-Ba, Pauline,Versace, Davy-Louis
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- Investigation of the molecular reactivity of bioactive oxiranylmethyloxy anthraquinones
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The design of a multitarget and multifunctional small molecule containing two functional groups reacting through different mechanisms represents an attractive goal for the medicinal chemist. The preparation of two bifunctional oxiranylmethyloxy anthraquinones, previously investigated as anticancer agents, is described here. These compounds combine a planar, DNA-intercalating and pro-oxidant anthraquinone scaffold and the alkylating epoxide functions which can covalently react with the nucleic acid. Their multilevel molecular reactivity was studied through a combination of analytical techniques: The DNA-binding properties were investigated using a mass spectrometry-based binding assay and by nuclear magnetic resonance, highlighting the formation of a covalent adduct with a nucleobase. Moreover, the contribution of the pro-oxidant redox cycling was evaluated.
- Ribaudo, Giovanni,Ongaro, Alberto,Zorzan, Maira,Pezzani, Raffaele,Redaelli, Marco,Zagotto, Giuseppe,Memo, Maurizio,Gianoncelli, Alessandra
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- Novel Chloroanthracyclines from Acetal-Alkene Cyclization
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Quinizarin is converted in seven steps into the homochiral acetal (3) in 69percent yield.Methallylation of (3) and reductive Claisen rearrangement gives (4) which is converted into four novel diastereomeric 9-chloroanthracyclines (7-10) by an unprecedented intramolecular acetal-alkene cyclization mediated by tin(IV) chloride in DMF.
- Brown, E. G.,Cambie, R. C.,Holroyd, S. E.,Johnson, M.,Rutiedge, P. S.,Woodgate, P. D.
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- Efficient reductive Claisen rearrangement of prop-2’-enyloxyanthraquinones and 2’-chloroprop-2’-enyloxyanthraquinones with iron powder in ionic liquids
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A rapid and selective iron-mediated reductive Claisen rearrangement of various prop-2’-enyloxyanthraquinones and 2’-chloroprop-2’-enyloxyanthraquinones to 1-hydroxy-2-(prop-2’-enyl)anthraquinones and anthrafurandiones is presented. All reactions are carried out in a mixture of ionic liquids, [Bzmim]Cl (1-benzyl-3-methylimidazolium chloride) and [Hmim]BF4 (1-methylimidazolium tetrafluoroborate), in short reaction times (5–35 min). Our study showed that 1-(prop-2’-enyloxy)anthraquinone is more active than 1-(2’-chloroprop-2’-enyloxy)anthraquinone to perform this rearrangement.
- Nadali, Samaneh,Khoshroo, Ali,Aghapour, Ghasem
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p. 883 - 895
(2018/06/07)
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- A new protocol for benzoannulation by double Claisen rearrangement and ring-closing metathesis reactions as key steps
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A new methodology for benzoannulation has been developed by using double Claisen rearrangement followed by a one-pot ring-closing metathesis and DDQ oxidation sequence.
- Kotha, Sambasivarao,Mandal, Kalyaneswar
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p. 2585 - 2588
(2007/10/03)
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