36065-27-7Relevant articles and documents
Continuous Flow Asymmetric Hydrogenation with Supported Ionic Liquid Phase Catalysts Using Modified CO2 as the Mobile Phase: From Model Substrate to an Active Pharmaceutical Ingredient
Geier, Daniel,Schmitz, Pascal,Walkowiak, J?drzej,Leitner, Walter,Franciò, Giancarlo
, p. 3297 - 3303 (2018)
The continuous flow asymmetric hydrogenation of (hetero)aromatic enamides has been realized using a Rh-Quinaphos catalyst immobilized in a supported ionic liquid phase (SILP) and employing supercritical CO2 modified with toluene (modCO2) as the mobile phase. This approach allows expansion of the scope of the original SILP/scCO2 system to nonvolatile substrates with poor solubility in pure CO2. The potential of a SILP catalyst in combination with modCO2 was demonstrated for an industrial case study using the continuous flow hydrogenation for the synthesis of a key intermediate of an active pharmaceutical ingredient (API) from AstraZeneca's portfolio. Toluene was selected as the most promising modifier, and the influence of the ratio of modifier to CO2 was evaluated in detail. The catalyst support was found to play a major role for maintaining constant performance and the use of hydrophobic fluorous reverse-phase silica (FRP-SiO2) instead of dehydroxylated silica strongly enhanced the long-term stability under continuous flow operation. Virtually a single enantiopure product was obtained over a prolonged time-on-stream of 90 h (quantitative single-pass conversion, ee > 99%) reaching a total turnover number of 10 300 at a space-time yield (STY) of 24 g L-1 h-1. No metal contamination was detected in the product solutions, indicating effective catalyst retention.
Preparation, characterization and catalytic activity of palladium catalyst supported on MgCO3 for dynamic kinetic resolution of amines
Ferreira, Marina M. M.,Cabreira, Camila R.,Chaves, Pedro H. K.,Labussiére, Gabriela M.,Zimpeck, Renata C.,De Lima, Sania M.,De Siqueira, Fernanda A.
, p. 2144 - 2149 (2018)
Pd nanoparticle catalyst loading 4.7 wt.percent was prepared by the deposition-precipitation method and characterized by X-ray diffraction and transmission electron microscopy (TEM). The crystallite size estimated from the integral width of the highest intensity line using the Scherrer equation was 2.3 nm. Images obtained from TEM showed an equal distribution of the particles size between 0-2 and 2-4 nm, and also a good dispersion of the nanoparticles on the catalyst support. The catalytic activity of this nanocatalyst was studied for racemization reactions of (S)-(-)-1-phenylethylamine. After that, the catalyst was used in the chemoenzymatic dynamic kinetic resolution (DKR) of some primary amines. Expressive yields and optical purities were obtained.
Decarboxylative Ritter-Type Amination by Cooperative Iodine (I/III)─Boron Lewis Acid Catalysis
Narobe, Rok,Murugesan, Kathiravan,Schmid, Simon,K?nig, Burkhard
, p. 809 - 817 (2022/01/15)
Recent years have witnessed important progress in synthetic strategies exploiting the reactivity of carbocations via photochemical or electrochemical methods. Yet, most of the developed methods are limited in their scope to certain stabilized positions in molecules. Herein, we report a metal-free system based on the iodine (I/III) catalytic manifold, which gives access to carbenium ion intermediates also on electronically disfavored benzylic positions. The unusually high reactivity of the system stems from a complexation of iodine (III) intermediates with BF3. The synthetic utility of our decarboxylative Ritter-type amination protocol has been demonstrated by the functionalization of benzylic as well as aliphatic carboxylic acids, including late-stage modification of different pharmaceutical molecules. Notably, the amination of ketoprofen was performed on a gram scale. Detailed mechanistic investigations by kinetic analysis and control experiments suggest two mechanistic pathways.
Tropylium-promoted Ritter reactions
Doan, Son H.,Hussein, Mohanad A.,Nguyen, Thanh Vinh
supporting information, p. 8901 - 8904 (2021/09/10)
The Ritter reaction used to be one of the most powerful synthetic tools to functionalize alcohols and nitriles, providing valuableN-alkyl amide products. However, this reaction has not been frequently used in modern organic synthesis due to its employment of strongly acidic and harsh reaction conditions, which often lead to complicated side reactions. Herein, we report the development of a new method using salts of the tropylium ion to promote the Ritter reaction. This method works well on a range of alcohol and nitrile substrates, giving the corresponding products in good to excellent yields. This reaction protocol is amenable to microwave and continuous flow reactors, offering an attractive opportunity for further applications in organic synthesis.
Electrocatalytic ethylbenzene valorization using a polyoxometalate@covalent triazine framework with water as the oxygen source
Chi, Yingnan,Dong, Jing,Geng, Weijie,Hu, Changwen,Li, Zhen,Liu, Chengpeng
supporting information, p. 7430 - 7433 (2021/08/03)
Ethylbenzene (EB) oxidation is an important transformation in the chemical industry. Herein, PMo10V2@CTF, a noble metal free electrocatalyst, was used to promote the oxidative upgrading of EB. Under ambient conditions, 65% of EB was converted to three value-added products using water as the oxygen source yielding a total Faraday efficiency of 90.4%. This excellent performance is ascribed to the homogeneous dispersion of PMo10V2and its dual role in the electrocatalytic process.
