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%.
Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
supporting information, (2022/03/07)
Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
Electrochemical bromofunctionalization of alkenes in a flow reactor
Seitz, Jakob,Wirth, Thomas
supporting information, p. 6892 - 6896 (2021/08/20)
The bromination of organic molecules has been extensively studied to date, yet there is still a demand for safe and sustainable methodologies. Hazardous reagents, selectivity, low atom economy and waste production are the most persisting problems of brominating reagents. The electrochemical oxidation of bromide to bromine is a viable strategy to reduce waste by avoiding chemical oxidants. Furthermore, thein situgeneration of reactive intermediates minimizes the risk of hazardous reagents. In this work, we investigate the electrochemical generation of bromine from hydrobromic acid in a flow electrochemical reactor. Various alkenes could be converted to their corresponding dibromides, bromohydrines, bromohydrin ethers and cyclized products in good to excellent yields.