19969-71-2Relevant articles and documents
Cooperative Interactions in the Second Coordination Sphere of Pyridazine/Pyridine Containing Polyazaheterocyclic Iron(II) Complexes Favor Protonation
Hammoud, Ahmad,Nshimyumuremyi, Jean-Boris,Bourotte, Jérémie,Lucaccioni, Fabio,Robeyns, Koen,D?rtu, Marinela M.,Garcia, Yann,Singleton, Michael L.
, p. 3253 - 3263 (2018)
The new pyridazine containing iron complexes, [N,N,N′,N′-tetrakis(3-pyridazylmethyl)propylenediamine]iron(II)(PF6)2 (1) and [N,N′-bis(2-pyridazylmethyl)-N,N′-bis(2-pyridylmethyl)propylenediamine]iron(II) (PF6)2 (2) were synthesized and their reactivity towards protonation was compared to that of the analogous tetrapyridine complex [N,N,N′,N′-tetrakis(2-pyridylmethyl)propylenediamine]iron(II)(PF6)2 (3). The solution and solid-state structures were confirmed by NMR and X-ray crystallographic studies. For 1–3, the ligands bind in a hexadentate fashion giving similar octahedral structures with an N6 coordination environment. Across the series, the increasing number of pyridazines has only modest effects on the spectroscopic and electrochemical properties of the metal. Nevertheless, their reactivity towards protonation is drastically different. While 2 and 3 decompose in the presence of strong acids, 1 is able to be stably protonated as a result of cooperative second sphere interactions.
Electroorganic synthesis of 2,5-dialkoxydihydrofurans and pyridazines on solid phase using polymer beads as supports
Nad, Sukanya,Breinbauer, Rolf
, p. 3654 - 3665 (2005)
Electroorganic synthesis has defied application in Solid-Phase Organic Synthesis (SPOS) so far. Typically more than 99.9% of the substrate molecules immobilized on a polymeric support are buried in the interior of the bead, and therefore are unable to undergo direct contact with a heterogeneous reagent such as an electrode. This intrinsic impediment for an electrochemical reaction can be overcome by the use of a redox mediator which shuttles electrons from the electrode to the polymer bound substrate molecules. This approach of indirect electroorganic synthesis was successfully applied for the 2,5-dialkoxylation of furans on solid phase. The oxidation products can be hydrolyzed and through condensation with hydrazine hydrate substituted pyridazines are produced in 50-65% overall yield. Georg Thieme Verlag Stuttgart.
Thiol Specific and Tracelessly Removable Bioconjugation via Michael Addition to 5-Methylene Pyrrolones
Zhang, Yingqian,Zhou, Xiaoping,Xie, Yonghui,Greenberg, Marc M.,Xi, Zhen,Zhou, Chuanzheng
, p. 6146 - 6151 (2017)
5-Methylene pyrrolones (5MPs) are highly thiol-specific and tracelessly removable bioconjugation tools. 5MPs are readily prepared from primary amines in one step. 5MPs exhibit significantly improved stability under physiologically relevant conditions and cysteine specificity compared to commonly used analogues, maleimides. Michael addition of thiol to 5MPs occurs rapidly, cleanly, and does not generate a stereocenter. The conjugates efficiently release thiols via retro-Michael reaction in alkaline buffer (pH 9.5) or via thiol exchange at pH 7.5. This unique property makes 5MPs valuable for the controlled release of conjugated cargo and temporary thiol protection. The utilization of 5MPs for protein immobilization and pull-down of active complexes is illustrated using E. coli. acetohydroxyacid synthase isozyme I.
The first de novo-designed antagonists of the human NK2 receptor
Ali, Mohammed A.,Bhogal, Nirmala,Findlay, John B. C.,Fishwick, Colin W. G.
, p. 5655 - 5658 (2005)
The de novo molecular design program SPROUT has been used in conjunction with a molecular model to produce a molecular template for a new class of NK2 receptor antagonist. An efficient, stereocontrolled synthesis of a small series of molecules,
Studies toward the synthesis of natural and unnatural dienediynes. Part 2: A practical approach to functionalised cyclopentenones
Caddick,Khan,Frost,Smith,Cheung,Pairaudeau
, p. 8953 - 8958 (2007/10/03)
The dienediyne natural products contain a functionalised dihydroxylated cyclopentane motif. A critical evaluation of the methods for the preparation and rearrangements of pyranones to give 4,5-dihydroxylated cyclopentenones is presented. (C) 2000 Elsevier Science Ltd.
Synthesis, physicochemical characterization, and biological evaluation of 2-(1'-hydroxyalkyl-3-hydroxypyridin-4-ones: Novel iron chelators with enhanced pFe3+ values
Liu, Zu D.,Khodr, Hicham H.,Liu, Ding Y.,Lu, Shu L.,Hider, Robert C.
, p. 4814 - 4823 (2007/10/03)
The synthesis of a range of 2-(1'-hydroxyalkyl)-3-hydroxypyridin-4-ones as bidentate iron(III) chelators with potential for oral administration is described. The pK(a) values of the ligands and the stability constants of their iron(III) complexes have been determined. Results indicate that the introduction of a 1'-hydroxyalkyl group at the 2-position leads to a significant improvement in the pFe3+ values. Such an effect was found to be greater with the hydroxyethyl substituent than with the hydroxy-methyl substituent, particularly in the cases of 1-ethyl-2(1'-hydroxyethyl)-3- hydroxypyridin-4-one (pFe3+ = 21.4) and 1,6-dimethyl-2-(1'-hydroxyethyl)3- hydroxypyridin-4-one (pFe3+ = 21.5) where an enhancement on pFe3+ values in the region of two orders of magnitude is observed, as compared with Deferiprone (1,2-dimethyl-3-hydroxypyridin-4-one) (pFe3+ = 19.4). The ability of these novel 3-hydroxypyridin-4-ones to facilitate the iron excretion in bile was investigated using a [59Fe] ferritin-loaded rat model. Chelators and prodrug chelators possessing high pFe3+ values show great promise in their ability to remove iron under in vivo conditions.
(2+4)-Cycloaddition with singlet oxygen. 17O-investigation of the reactivity of furfuryl alcohol endoperoxide
Braun, André M.,Dann, Hans,Gassmann, Ernst,Gerothanassis, Ioannis,Jakob, Laurent,Kateva, Jordanka,Martinez, Claudia G.,Oliveros, Esther
, p. 868 - 874 (2007/10/03)
In earlier work, the use of furfuryl alcohol as a specific singlet oxygen acceptor was proposed because of the high ratio between the rate constants of chemical reaction and physical quenching. In contrast to furfuryl aldehyde, a number of products are formed by this type II photooxidation of furfuryl alcohol. These products may be derived from the endoperoxide of furfuryl alcohol as a common intermediate. The present work focuses on the reactivity of this endoperoxide that was marked specifically by the use of 17O2 as a source for singlet oxygen. The analyses of the stable products, their yields and their labeling distribution reveal a strong solvent effect on the primary reaction pathways, and nucleophilic substitution reactions leading to hydroperoxide intermediates are dominant.
