- Ligand Design for Isomer-Selective Oxorhenium(V) Complex Synthesis
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Recently, N,N-trans Re(O)(LN-O)2X (LN-O = monoanionic N-O chelates; X = Cl or Br prior to being replaced by solvents or alkoxides) complexes have been found to be superior to the corresponding N,N-cis isomers in the cataly
- Liu, Jinyong,Su, Xiaoge,Han, Mengwei,Wu, Dimao,Gray, Danielle L.,Shapley, John R.,Werth, Charles J.,Strathmann, Timothy J.
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- 2-(4′,4′-dimethyl-3′,4′-dihydrooxazol-2′-yl) phenol: Some first-row transition metal complexes of this naturally occurring binding group
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The synthesis and characterization of monomeric MnIII, CoII, NiII, CuII, and ZnII phenolates derived from a biologically relevant ligand, 2-(4′,4′-dimethyl-3′,4′-dihydrooxazol-2′-yl)- phenol (1), are
- Mugesh, Govindasamy,Singh, Harkesh B.,Butcher, Ray J.
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- Oxorhenium(V) complexes with phenolate-oxazoline ligands: Influence of the isomeric form on the O-atom-transfer reactivity
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The bidentate phenolate-oxazoline ligands 2-(2′-hydroxyphenyl)-2-oxazoline (1a, Hoz) and 2-(4′,4′-dimethyl-3′,4′-dihydrooxazol-2′-yl)phenol (1b, Hdmoz) were used to synthesize two sets of oxorhenium(V) complexes, namely, [ReOCl2(L)(PPh3)] [L = oz (2a) and dmoz (2b)] and [ReOX(L)2] [X = Cl, L = oz (3a or 3a′); X = Cl, L = dmoz (3b); X = OMe, L = dmoz (4)]. Complex 3a′ is a coordination isomer (N,N-cis isomer) with respect to the orientation of the phenolate-oxazoline ligands of the previously published complex 3a (N,N-trans isomer). The reaction of 3a′ with silver triflate in acetonitrile led to the cationic compound [ReO(oz)2(NCCH3)](OTf) ([3a′](OTf)). Compound 4 is a rarely observed isomer with a trans-O=Re-OMe unit. Complexes 3a, 3a′, [3a′](OTf), and 4 were tested as catalysts in the reduction of a perchlorate salt with an organic sulfide as the O acceptor and found to be active, in contrast to 2a and 2b. A comparison of the two isomeric complexes 3a and 3a′ showed significant differences in activity: 87% 3a vs 16% 3a′ sulfoxide yield. When complex [3a′](OTf) was used, the yield was 57%. Density functional theory calculations circumstantiate all of the proposed intermediates with N,N-trans configurations to be lower in energy compared to the respective compounds with N,N-cis configurations. Also, no interconversions between N,N-trans and N,N-cis configurations are predicted, which is in accordance with experimental data. This is interesting because it contradicts previous mechanistic views. Kinetic analyses determined by UV-vis spectroscopy on the rate-determining oxidation steps of 3a, 3a′, and [3a′](OTf) proved the N,N-cis complexes 3a′ and [3a′](OTf) to be slower by a factor of ~4.
- Schachner, J?rg A.,Terfassa, Belina,Peschel, Lydia M.,Zwettler, Niklas,Belaj, Ferdinand,Cias, Pawel,Gescheidt, Georg,M?sch-Zanetti, Nadia C.
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- Substitution Effect on 2-(Oxazolinyl)-phenols and 1,2,5-Chalcogenadiazole -Annulated Derivatives: Emission-Color-Tunable, Minimalistic Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
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Minimalistic 2-(oxazolinyl)-phenols substituted with different electron-donating and -withdrawing groups as well as 1,2,5-chalcogenadiazole-annulated derivatives thereof were synthesized and investigated in regard to their emission behavior in solution as well as in the solid state. Depending on the nature of the incorporated substituent and its position, emission efficiencies were increased or diminished, resulting in AIE or ACQ characteristics. Single-crystal analysis revealed J- and H-type packing motifs and a so-far undescribed isolation of ESIPT-based fluorophores in the keto form.
- G?bel, Dominik,Rusch, Pascal,Duvinage, Daniel,Stauch, Tim,Bigall, Nadja-C.,Nachtsheim, Boris J.
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p. 14333 - 14355
(2021/10/20)
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- Aerobic C(sp2)-H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
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The direct hydroxylation of 2-aryloxazolines via a deprotonative magnesiation using TMPMgCl·LiCl and subsequent oxidation with molecular oxygen or air as a green oxidant is reported. This method proceeds under mild conditions at room temperature with high regioselectivity and chemoselectivity. The obtained phenols exhibit tunable luminescence properties, induced by excited-state intramolecular proton transfer. This method opens a new opportunity for the sustainable synthesis of luminescent organic molecules.
- G?bel, Dominik,Clamor, Nils,Lork, Enno,Nachtsheim, Boris J.
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p. 5373 - 5377
(2019/06/07)
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- Base-Induced Cyclisation of ortho -Substituted 2-Phenyloxazolines to Give 3-Aminobenzofurans and Related Heterocycles
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Treatment of ortho -benzyloxyphenyloxazolines with butyllithium and potassium tert -butoxide results in cyclisation with ring opening of the oxazoline to give 2-aryl-3-aminobenzofurans. The reaction also occurs with the corresponding benzylthio and benzylamino compounds to give benzothiophenes and indoles, respectively. Use of an ortho -allyloxyphenyloxazoline gives the corresponding 2-vinylbenzofuran, while both α-methylbenzyloxy and benzylsulfonyl compounds form stable spirooxazolidine products. The X-ray structure of an aminobenzothiophene product has been determined.
- Aitken, R. Alan,Harper, Andrew D,Slawin, Alexandra M. Z.
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p. 1738 - 1742
(2017/10/06)
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- Adding the right (or left) twist to tris-chelate complexes-coordination chemistry of chiral oxazolylphenolates with M3+ ions (M = Al or lanthanide)
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A series of homoleptic tris-chelate complexes ML3 (M = Al or rare earth; L = chiral or achiral oxazolyl phenolate or -naphtholate) is reported. In all cases, complexes crystallize as mer-isomers and complete diastereoselectivity is observed on
- Aspinall, Helen C.,Bacsa, John,Beckingham, Oliver D.,Eden, Edward G. B.,Greeves, Nicholas,Hobbs, Matthew D.,Potjewyd, Frances,Schmidtmann, Marc,Thomas, Christopher D.
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supporting information
p. 1434 - 1442
(2014/01/06)
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- Synthesis and biological evaluation of some new 2-oxazoline and salicylic acid derivatives
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Starting from methyl salicylate and 2-amino-2-(hydroxymethyl)propane-1,3- diol 1a, or 2-amino- 2-methylpropane-1-ol 1b, the 2-oxazoline derivatives 2a, 2b or 3, as well as mono- 4a and 4b and bis- 5a and 5b derivatives of salicylic acid were synthesized. Reactions were performed by microwave irradiation in the presence of tetrabutylammonium bromide or metallic sodium as catalyst, as well as by conventional heating. Microwave-induced reaction of some diols, diamines and amino alcohols with methyl salicylate gave mono- and/or bis- derivatives of salicylic acid 4c, 5c, 5d, 6c, 8c, 7a, 7b, 8a and 8b. The mono- and bis-salicyloyl derivatives 4c, 5c and 5d were transformed to the corresponding phenyl-azo derivatives 9, 10c and 10d. The structure of compound 3 was proved by the X-ray analysis and the R-configuration on its stereocenter was confirmed. The antioxidant and cytotoxic activities of the synthesized derivatives were evaluated in a series of in vitro tests. Compounds 5d, 8b and 8c exhibited very strong activity against hydroxyl radical. Six 4c, 5d, 8a-c, 10c of 16 tested compounds inhibited growth of MDA-MB-231 cells at a nanomolar concentration. Compounds 8c and 10c showed high cytotoxicity against MCF7 cells, whereas compounds 4c, 5d, 8a-c and 10d showed high activity against K562 cells. ARKAT-USA, Inc.
- Djurendic, Evgenija,Vujaskovic, Sanja Dojcinovic,Sakac, Marija,Ajdukovic, Jovana,Gakovic, Andrea,Kojic, Vesna,Bogdanovic, Gordana,Klisuric, Olivera,Gasi, Katarina Penov
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experimental part
(2011/05/11)
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- Ortho-directed functionalization of arenes using magnesate bases
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Ortho-directed functionalisation of arenes using lithium alkylmagnesate bases were achieved, demonstrating the potential use of arylmagnesates as suitable arylanions, without a further transmetallation step, for challenging functionalizations such as fluorination, hydroxylation, arylation, vinylation and alkylation through epoxide ring-opening.
- Bellamy, Estelle,Bayh, Omar,Hoarau, Christophe,Trecourt, Francois,Queguiner, Guy,Marsais, Francis
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supporting information; experimental part
p. 7043 - 7045
(2010/11/02)
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- A novel and direct synthesis of 1,3,4-oxadiazoles or oxazolines from carboxylic acids using cyanuric chloride/indium
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Direct synthesis of various oxazolines and 1,3,4-oxadiazoles from carboxylic acids was achieved using cyanuric chloride/indium under very mild conditions.
- Kangani, Cyrous O.,Day, Billy W.
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experimental part
p. 5332 - 5335
(2009/12/06)
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- Lanthanide complexes of an oxazoline-phenoxide hybrid chelate
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The synthesis of 2-(2′-hydroxy-3′-allylphenyl)-4,4-dimethyl-2- oxazoline, H-Allox (3), and lanthanide tris chelate complexes, mer-Ln(Allox)3 (Ln = La (4), Ce (5), Sm (6), Er (7), and Y (8)), derived from it are reported. A six-coordinate mer ge
- Berg, David J.,Zhou, Chuanjian,Barclay, Tosha,Fei, Xuening,Feng, Shengyu,Ogilvie, Kevin A.,Gossage, Robert A.,Twamley, Brendan,Wood, Mark
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p. 449 - 459
(2007/10/03)
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- A facile one stage synthesis of oxazolines under microwave irradiation
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A rapid, high yielding procedure for the synthesis of 2-substituted oxazolines has been achieved under microwave irradiation from alkyl and aryl nitriles and β-amino alcohols using a mild Lewis acid catalyst.
- Clarke, David S.,Wood, Robin
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p. 1335 - 1340
(2007/10/03)
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