- Luminescent 'On-Off' CdSe/ZnS quantum dot chemodosimeter for hydroxide based on photoinduced electron transfer from a carboxylate moiety
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A CdSe-ZnS quantum dot (QD) has been surface functionalised by a place exchange reaction with p-mercaptomethyl benzoate synthesized by a three-step procedure. The resulting lumophore-spacer-receptor QD-conjugate was characterized by IR, UV-visible and fluorescence spectroscopy. The emission profile of the QD reveals a narrow emission peak centred at 542 nm. Addition of hydroxide to the solution containing the QD-conjugate results in quenching of the original fluorescence, which is attributed to a photoinduced electron transfer reaction from the electron-rich benzoate moiety to the QD valence band. This is the first reported example of fluorescent quenching of a CdSe-ZnS QD luminescence by an aryl carboxylate moiety.
- Gauci, Lara A.,Kelland, Lindsay G.,Magri, David C.
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- Benzylic Thio and Seleno Newman-Kwart Rearrangements
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The thermally induced OBn → SBn and OBn → SeBn migration reactions facilitate the rearrangement of O-benzyl thio- and selenocarbamates [BnOC(=X)NMe2] (X = S or Se) into their corresponding S-benzyl thio- and Se-benzyl selenocarbamates [BnXC(=O)NMe2] (X = S or Se). A series of substituted O-benzyl thio- and selenocarbamates were synthesized and rearranged in good yields of 33-88%. The reaction rates are higher for substrates with electron-donating groups in the 2 or 4 position of the aromatic ring, but the rearrangement also proceeds with electron-withdrawing substituents. The rearrangement follows first-order reaction kinetics and proceeds via a tight ion pair intermediate consisting of the benzylic carbocation and the thio- or selenocarbamate moiety. Computational studies support these findings.
- Eriksen, Kristina,Ulfkj?r, Anne,S?lling, Theis I.,Pittelkow, Michael
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p. 10786 - 10797
(2018/09/06)
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- Synthesis of optically active thromboxane A2 and Leukotriene D4 receptor antagonists
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Both (+)- and (-)-4-{[(2-{4-cUorophenylsulfonylamino}-1-{3-[(Q-2-(7-cWoro- 2-quinolyl)-vinyl]phenyl}ethyl)-thio]methyl}benzoic acid (1), Thromboxane A2 and Leukotriene D4 receptor dual antagonist were synthesized. Racemic methyl 4-({[2-amino-1-(3-hydroxym
- Kawazoe, Souichirou,Okamoto, Yoshinori,Yokota, Masaki,Kubota, Hirokazu,Naito, Ryo,Takeuchi, Makoto,Ieda, Shigeru,Okada, Minoru,Oriyama, Takeshi
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p. 127 - 140
(2014/02/14)
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- Development of a novel benzyl mercaptan as a recyclable odorless substitute of hydrogen sulfide
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2,4,6-Trimethoxybenzyl mercaptan (4) was developed as an odorless substitute of hydrogen sulfide to afford β-mercapto carbonyl compounds in a Michael addition and to convert alkyl bromides into alkanethiols. Detrimethoxybenzylation of the Michael adducts prepared from 4 and α,β-unsaturated esters or ketones was facilely carried out by treatment with a solvent mixture of trifluoroacetic acid and toluene to give β-mercapto carbonyl compounds. Successive alkaline hydrolysis of 2,4,6-trimethoxybenzyl isothiouronium salt, which was obtained as a side product, regenerated 4 accompanying disulfide 8 in good yield. The disulfide 8 was also converted into 4 by reduction with LiAlH4. A similar protocol was applicable to the synthesis of alkanethiols using the S N2 reaction of alkyl bromides. Our method could be complementary to the classical method of using malodorous benzyl mercaptan as a nucleophile and Birch reduction for debenzylation. Georg Thieme Verlag Stuttgart.
- Matoba, Manabu,Kajimoto, Tetsuya,Node, Manabu
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p. 1930 - 1934
(2008/03/27)
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- Stereo- and Oligo-controlled Synthesis of Oligo-p-benzoic Acid Derivatives: Basic Building Blocks for Oligos
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Oligobenzoic acids of up to four aromatic units are synthesized in complete oligo- and excellent (E)-stereo-control via an iterative modified Ramberg-Baecklund reaction; these extended ?-systems can be used to construct oligos in good yields.
- Chan, Tze-Lock,Chow, Hak-Fun,Fong, Sun,Leung, Man-kit,Tu, Jingren
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p. 1919 - 1920
(2007/10/02)
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- (E)-3-[[[[6-(2-Carboxyethenyl)-5-[[8-(4-methoxyphenyl)octyl]oxy]-2- pyridinyl]-methyl]thio]methyl]benzoic acid and related compounds: High affinity leukotriene B4 receptor antagonists
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(E)-3-[[[[6-(2-Carboxyethenyl)-5-[[8-(4-methoxyphenyl)octyl]oxy]-2- pyridinyl]-methyl]thio]methyl]benzoic acid (11, SB 201993) is a novel, potent LTB4 receptor antagonist. Compound 11 arose from a structure-activity study of a series of trisubstituted pyridines that demonstrated LTB4 receptor antagonist activity. The placement of an additional methylene unit in the sulfur containing chain linking the pyridine and benzoic acid moieties of lead compound 8 (K(i) = 80 nM) resulted in a greater than 10-fold increase in receptor affinity. Additionally, in this new series of compounds, the oxidation state of the sulfur was found to be critical to the activity, i.e., the sulfoxide and sulfone showed substantially lower affinity for the LTB4 receptor. Compound 11 competitively inhibits the binding of [3H]LTB4 to LTB4 receptors on human polymorphonuclear leukocutes with a K(i) of 7.1 nM and blocks both the LTB4-induced calcium mobilization and the LTB4-induced degranulation responses in these cells with IC50 values of 131 and 271 nM, respectively. Compound 11 demonstrated oral LTB4 antagonist activity as well as topical antiinflammatory activity in the mouse.
- Daines,Chambers,Eggleston,Foley,Griswold,Haltiwanger,Jakas,Kingsbury,Martin,Pendrak,Schmidt,Tzimas,Sarau
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p. 3327 - 3336
(2007/10/02)
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