22927-05-5Relevant articles and documents
Destabilized Carbocations Caged in Water Microdroplets: Isolation and Real-Time Detection of α-Carbonyl Cation Intermediates
Kumar, Anubhav,Mondal, Supratim,Sandeep,Venugopalan, Paloth,Kumar, Anil,Banerjee, Shibdas
supporting information, p. 3347 - 3352 (2022/03/03)
Over the last 50 years, proposals of α-carbonyl cation intermediates have been driven by chemical intuition and indirect evidence. Recently, wide interest in α-carbonyl cation chemistry has opened new gates to prepare α-functionalized carbonyl compounds. Though these intrinsically unstable carbocations are formed under forcing conditions (e.g., in a strong acid medium), their fleeting existence prohibits direct observation or spectroscopic measurement. We report that high-speed aqueous microdroplets can directly capture α-carbonyl cation intermediates from various reactions (Friedel-Crafts arylation, deoxygenation, and azidation) upon bombarding with the corresponding reaction aliquots. The α-carbonyl cations caged in water droplets are then desorbed to the gas phase, allowing their successful measurement by mass spectrometry. This has also enabled us to simultaneously monitor the relative abundance of the associated precursor, α-carbonyl cation intermediate, and product during the progress of the reaction.
Lewis Acid Assisted Electrophilic Fluorine-Catalyzed Pinacol Rearrangement of Hydrobenzoin Substrates: One-Pot Synthesis of (±)-Latifine and (±)-Cherylline
Shi, Hui,Du, Chuan,Zhang, Xinhang,Xie, Fukai,Wang, Xiaoyu,Cui, Shanshan,Peng, Xiaoshi,Cheng, Maosheng,Lin, Bin,Liu, Yongxiang
, p. 1312 - 1319 (2018/02/09)
A microwave-irradiated solvent-free pinacol rearrangement of hydrobenzoin substrates catalyzed by a combination of N-fluorobenzenesulfonimide and FeCl3·6H2O was developed. Its selectivity was first investigated by density functional theory (DFT) calculations. Then the functional group tolerance was examined by synthesizing a series of substrates designed based on the insight provided by the DFT calculations. The application of the methodology was demonstrated by the efficient one-pot synthesis of (±)-latifine and (±)-cherylline, both are 4-aryltetrahydroisoquinoline alkaloids isolated from Amaryllidacecae plants.
A gold catalytic pinacone method of rearrangement of
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Paragraph 0047; 0048; 0049; 0050; 0057; 0058; 0059-0061, (2017/11/22)
The invention provides a method used for catalytic rearrangement of pinacol with gold. A reaction general formula is disclosed in the invention, wherein R1, R2, R3, and R4 may be common alkyl, cycloalkyl, and aromatic rings. A gold catalyst needed by reac
Direct one-pot synthesis of 2,3-diarylbuta-1,3-diene via self-coupling of acetophenones
Li, Jian,Li, Shaoyu,Jia, Xueshun
experimental part, p. 1529 - 1531 (2009/04/07)
A mild and straightforward route to 2,3-diarylbuta-1,3-diene is described here. By treatment with SmI2-Ac20, acetophe-none and its analogues underwent self-coupling reactions and subsequent elimination to give a series of 2,3-diarylbuta-1,3-dienes in moderate to good yields.
SiCl4-Zn induced reductive coupling of carbonyl compounds: novel and efficient routes for one-pot syntheses of 1,2,3-triaryl-2-propen-1-ones and pinacolones at room temperature
Salama, Tarek A.,Elmorsy, Saad S.,Khalil, Abdel-Galel M.
, p. 4395 - 4398 (2008/02/03)
An unprecedented one-pot reductive trimerization of aromatic aldehydes to 1,2,3-triaryl-2-propen-1-ones as well as tandem reductive coupling-rearrangements of aryl ketones to pinacolone analogues was efficiently achieved using tetrachlorosilane-zinc at room temperature.
Acid catalysis vs. electron-transfer catalysis via organic cations or cation-radicals as the reactive intermediate. Are these distinctive mechanisms?
Rathore, Rajendra,Kochi, Jay K.
, p. 114 - 130 (2007/10/03)
Proton transfer to aromatic and olefinic donors (D) leads to the facile interchange of transient carbocations (DH+) and cation-radical (D+.). The same types of cation and cation-radical are reactive intermediates in the acid catalysis and the electron-transfer catalysis of such organic transformations as benzylic coupling, epoxide/pinacol rearrangements and cis-trans isomerization of stilbenes when they are both carried out under otherwise identical reaction conditions. However, the rapid exchange of diamagnetic cations and paramagnetic cation-radicals blurs the traditional view of separate electrophilic and homolytic processes, and rigorous experimental evidence is required to establish whether acid catalysis and electron-transfer catalysis actually represent distinct mechanistic categories. Acta Chemica Scandinavica 1998.
Reductive Coupling of Carbonyl Compounds with Zinc and Trimethylchlorosilane To Produce O-Silylated Pinacols. Effect of Ultrasonic Waves
So, Jeung-Ho,Park, Moon-Kyeu,Boudjouk, Philip
, p. 5871 - 5875 (2007/10/02)
Trimethylchlorosilane reacts with carbonyl compounds in the presence of zinc to give O-silylated pinacols, vicinal bis(trimethylsiloxy)alkanes, in good yields via reductive dimerization.This is very mild route to bis(siloxy)alkanes, which are easily converted to pinacols or pinacolones in excellent yields.Electron-donating groups accelerate coupling while electron-withdrawing groups have an inhibiting effect.Cross-coupling reactions yield a mixture of bis(siloxy)alkanes.Ultrasonic irradiations of these reactions increases the yields up to 50percent compared to stirring at the same temperature.
