163165-91-1Relevant articles and documents
Ligand Design for Isomer-Selective Oxorhenium(V) Complex Synthesis
Liu, Jinyong,Su, Xiaoge,Han, Mengwei,Wu, Dimao,Gray, Danielle L.,Shapley, John R.,Werth, Charles J.,Strathmann, Timothy J.
, p. 1757 - 1769 (2017)
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
Oxorhenium(V) complexes with phenolate-oxazoline ligands: Influence of the isomeric form on the O-atom-transfer reactivity
Schachner, J?rg A.,Terfassa, Belina,Peschel, Lydia M.,Zwettler, Niklas,Belaj, Ferdinand,Cias, Pawel,Gescheidt, Georg,M?sch-Zanetti, Nadia C.
, p. 12918 - 12928 (2014)
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.
Aerobic C(sp2)-H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
G?bel, Dominik,Clamor, Nils,Lork, Enno,Nachtsheim, Boris J.
, p. 5373 - 5377 (2019/06/07)
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.