2425-28-7Relevant articles and documents
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Buckles,Maurer
, p. 1585,1587 (1953)
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Metalated Ir–CNP Complexes Containing Imidazolin-2-ylidene and Imidazolidin-2-ylidene Donors – Synthesis, Structure, Luminescence, and Metal–Ligand Cooperative Reactivity
Hernández-Juárez, Martín,Sánchez, Práxedes,López-Serrano, Joaquín,Lara, Patricia,González-Herrero, Pablo,Rendón, Nuria,álvarez, Eleuterio,Paneque, Margarita,Suárez, Andrés
, p. 3944 - 3953 (2020)
The iridium complex 1 based on a metalated CNP ligand containing an imidazolin-2-ylidene fragment has been prepared by treatment of the ligand precursor 4 with Ag2O followed by reaction with [IrCl(COE)2]2. The chlorohydride imidazolidin-2-ylidene complex 6, which is isostructural to 1, was synthetized by reaction of the previously reported dihydride derivative 3 with CH2Cl2. Complexes 1 and 6 exhibit luminescence arising from a 3MLCT/ILCT state involving the metalated CNP ligand, which is particularly intense for 1 in the solid state at 298 K. Furthermore, the reactivity of complexes 1 and 6 towards bases was compared. Deprotonation of 1 with KOtBu produced the selective formation of the dinuclear complex 7; meanwhile, the reaction of 6 led to a complex mixture of products. The same reactions carried out in the presence of PPh3 produced the selective deprotonation of the P-bonded methylene bridges of 1 and 6, yielding the isostructural derivatives 9 and 10. DFT calculations performed on the uNHC-containing tautomers I and II, and the sNHC-based isomers III and IV, showed that the NHC-deprotonated derivatives II and IV are more stable by 3.20 and 2.73 kcal mol–1, respectively, than their P-deprotonated counterparts (I and III). However, a reverse stability order was observed for hexacoordinated tautomers I·L and II·L, and III·L and IV·L (L = PPh3, CO, MeCN). Finally, the catalytic activity of complex 3 in the transfer hydrogenation of ketones has been assessed.
In situ NMR study of asymmetric borane reduction reaction - An abnormal factor in the temperature effect on the bis-oxazaborolidine catalyst and the relationship between the catalyst structure and selectivity
Zhao, Jinkai,Bao, Xinhe,Liu, Xiumei,Wan, Boshun,Han, Xiuwen,Yang, Caiguang,Hang, Jiangfeng,Feng, Yan,Jiang, Biao
, p. 3351 - 3359 (2000)
The relationship between the structure of the catalyst and the selectivity in the asymmetric borane reduction reaction of prochiral ketones is discussed. The variation of the catalyst itself at low temperature is observed by the in situ NMR method and the origin of the temperature effect of the reaction is proposed. It is concluded that the amount of the effective component of the catalyst present has an important effect on the enantioselectivity. Copyright (C) 2000 Elsevier Science Ltd.
New chiral borohydride based reducing agent: Asymmetric reduction of 9-anthryl trifluoromethyl ketone and other carbonyl compounds
Maiti, Dilip K.,Bhattacharya, Pranab K.
, p. 99 - 108 (1998)
(S)-(+)-2-(α-Hydroxybenzyl)benzimidazole and (S)-(-)-2-benzimidazole-1-ethanol were synthesised and converted to chiral borohydrides which reduced prochiral ketones to the corresponding chiral alcohols in high yields (80 to 100%, e.e. 42 to 95%). This is the first report of sodium borohydride modified by 1,2-amino alcohol.
Enantioselective borane reduction of aromatic ketones catalyzed by chiral aluminum alkoxides
Fu, I.-Pin,Uang, Biing-Jiun
, p. 45 - 48 (2001)
The asymmetric borane reduction of prochiral ketones with an alkoxide catalyst prepared in situ from aluminum tri-iso-propoxide and (R)-binaphthol was examined. Using these conditions, alcohols were obtained in high yield and e.e.'s of up to 83%.
Unmasking the Hidden Carbonyl Group Using Gold(I) Catalysts and Alcohol Dehydrogenases: Design of a Thermodynamically-Driven Cascade toward Optically Active Halohydrins
Escot, Lorena,González-Granda, Sergio,Gotor-Fernández, Vicente,Lavandera, Iván
, p. 2552 - 2560 (2022/02/16)
A concurrent cascade combining the use of a gold(I) N-heterocyclic carbene (NHC) and an alcohol dehydrogenase (ADH) is disclosed for the synthesis of highly valuable enantiopure halohydrins in an aqueous medium and under mild reaction conditions. The meth
A General Method for the Dibromination of Vicinal sp3C-H Bonds Exploiting Weak Solvent-Substrate Noncovalent Interactions
Qi, Zaojuan,Li, Weihe,Niu, Yanning,Benassi, Enrico,Qian, Bo
supporting information, p. 2399 - 2404 (2021/03/03)
A general procedure of 1,2-dibromination of vicinal sp3 C-H bonds of arylethanes using N-bromosuccinimide as the bromide reagent without an external initiator has been established. The modulation of the strength of the intermolecular noncovalent interactions between the solvent and arylethane ethanes, quantitatively evaluated via quantum chemical calculations, allows us to circumvent the fact that arylethane ethane cannot be dibrominated through traditional methods. The mechanism was explored by both experiments and quantum chemical calculations, revealing a radical chain with HAA process.
