5211-62-1Relevant academic research and scientific papers
Palladium(II)-catalyzed aerobic dialkoxylation of styrenes: A profound influence of an o-phenol
Schultz, Mitchell J.,Sigman, Matthew S.
, p. 1460 - 1461 (2006)
We report a Pd(II)-catalyzed aerobic dialkoxylation of styrene derivatives that requires an o-phenol. Initial scope and preliminary mechanistic studies are presented in which the o-phenol is proposed to facilitate the formation of a quinone methide intermediate. Copyright
Markovnikov Wacker-Tsuji Oxidation of Allyl(hetero)arenes and Application in a One-Pot Photo-Metal-Biocatalytic Approach to Enantioenriched Amines and Alcohols
Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
, p. 4096 - 4108 (2021/08/19)
The Wacker-Tsuji aerobic oxidation of various allyl(hetero)arenes under photocatalytic conditions to form the corresponding methyl ketones is presented. By using a palladium complex [PdCl2(MeCN)2] and the photosensitizer [Acr-Mes]ClO4 in aqueous medium and at room temperature, and by simple irradiation with blue led light, the desired carbonyl compounds were synthesized with high conversions (>80%) and excellent selectivities (>90%). The key process was the transient formation of Pd nanoparticles that can activate oxygen, thus recycling the Pd(II) species necessary in the Wacker oxidative reaction. While light irradiation was strictly mandatory, the addition of the photocatalyst improved the reaction selectivity, due to the formation of the starting allyl(hetero)arene from some of the obtained by-products, thus entering back in the Wacker-Tsuji catalytic cycle. Once optimized, the oxidation reaction was combined in a one-pot two-step sequential protocol with an enzymatic transformation. Depending on the biocatalyst employed, i. e. an amine transaminase or an alcohol dehydrogenase, the corresponding (R)- and (S)-1-arylpropan-2-amines or 1-arylpropan-2-ols, respectively, could be synthesized in most cases with high yields (>70%) and in enantiopure form. Finally, an application of this photo-metal-biocatalytic strategy has been demonstrated in order to get access in a straightforward manner to selegiline, an anti-Parkinson drug. (Figure presented.).
Method for isomerizing cis-anethole by using catalyst
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Paragraph 0017; 0018, (2020/09/23)
The invention discloses a method for isomerizing cis-anethole by using a catalyst in the technical field of anethole preparation. The method comprises the following steps: 1, heating cis-anethole to 95-110 DEG C; 2, adding sodium hydrogen sulfate into the heated cis-anethole to obtain a mixture, heating the mixture for 8-10 min until the temperature of the mixture is 155-200 DEG C, and keeping thetemperature of the mixture constant for 1-1.2 hours to obtain a reaction product, wherein the weight ratio of the sodium bisulfate to the cis-anethole before heating is (1-5): 100; 3, cooling the reaction product to room temperature, carrying out liquid separation treatment to obtain a mixed solution, adding a sodium carbonate solution into the mixed solution, carrying out an oscillation reactionfor 5-6 min to obtain a neutralization solution, and separating the neutralization solution to obtain an upper-layer trans-anethole mixed solution, wherein the weight ratio of the sodium carbonate solution to the cis-anethole is (1-1.2): 10. According to the scheme, sodium hydrogen sulfate is adopted as a catalyst, isomerization of cis-anethole can be achieved by heating and stirring for 1 h at the temperature of 150-200 DEG C in the presence of sodium hydrogen sulfate, use of rare metals such as rhodium chloride is avoided, and the cis-anethole isomerization cost is greatly reduced.
Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
supporting information, p. 1778 - 1781 (2020/03/11)
A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
Iron powder and tin/tin chloride as new reducing agents of Meerwein arylation reaction with unexpected recycling to anilines
Abdelwahab, Ahmed B.,El-Sawy, Eslam R.,Kirsch, Gilbert
supporting information, p. 526 - 538 (2020/01/08)
Simple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO2 from an excess of NaNO2/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture.
Stereoselective Synthesis of 1-Arylpropan-2-amines from Allylbenzenes through a Wacker-Tsuji Oxidation-Biotransamination Sequential Process
González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
, p. 2582 - 2593 (2019/05/15)
Herein, a sequential and selective chemoenzymatic approach is described involving the metal-catalysed Wacker-Tsuji oxidation of allylbenzenes followed by the amine transaminase-catalysed biotransamination of the resulting 1-arylpropan-2-ones. Thus, a series of nine optically active 1-arylpropan-2-amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium. The Wacker-Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1-arylpropan-2-amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family. (Figure presented.).
Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
De Souza, Aline A. N.,Silva, Nathalia S.,Müller, Andressa V.,Polo, André S.,Brocksom, Timothy J.,De Oliveira, Kleber T.
, p. 15077 - 15086 (2019/01/03)
We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
Fluorine as a Traceless Directing Group for the Regiodivergent Synthesis of Indoles and Tryptophans
Andries-Ulmer, Anna,Brunner, Christoph,Rehbein, Julia,Gulder, Tanja
supporting information, p. 13034 - 13041 (2018/09/27)
Despite ample evidence for the unique reactivity offered by hypervalent F-iodanes, mechanistic investigations fall far behind. In order to shed light on the unusual behavior of such F-reagents, we conducted computational and experimental studies on the chemodivergent transformation of styrenes. We identified the spirocyclic F-cyclopropane as the common intermediate for both the C,H-fluorination and C,H-amination pathways. The fate of this key compound is determined by the extent of cationic charge delocalization controlled by the N-substituents. Exploiting this phenomenon, a multitude of different transformations have become available, leading, i.e., to the regiodivergent synthesis of indoles and tryptophans.
Salicylic Acid-Catalyzed Arylation of Enol Acetates with Anilines
Felipe-Blanco, Diego,Gonzalez-Gomez, Jose C.
supporting information, p. 2773 - 2778 (2018/07/29)
α-Aryl ketones are both structure moieties commonly found in bioactive compounds and versatile synthetic intermediates for the preparation of drug-like molecules. An operationally simple and scalable protocol has been developed to prepare α-aryl ketones from readily available aromatic amines and enol acetates (or silyl enol ethers). This metal-free methodology features the use of salicylic acid as a convenient catalyst to promote the formation of aryl radicals from in-situ generated aryl diazonium salts, without demanding thermal or photochemical activation. The mild reaction conditions used are compatible with anilines substituted with diverse functionalities. Structural elaboration of some prepared α-aryl ketones was accomplished to illustrate their usefulness as building blocks. (Figure presented.).
Carbazolyl phosphorus ligand as well as preparation method and application thereof
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Paragraph 0167; 0168; 0169; 0170; 0171; 0172, (2017/07/04)
The invention is suitable for the technical fields of organic compounds and synthesis, and provides a carbazolyl phosphorus ligand as well as a preparation method and application thereof. The carbazolyl phosphorus ligand is one of a compound 1, a compound 2 and a compound 3 with structures shown by a formula 1, a formula 2 and a formula 3 (shown in the description) respectively, wherein R1 is phenyl or alkyl, R2, R3, R4, R5, R6, R7, R8 and R9 independently are one of hydrogen, C5-C10 alkyl, methoxyl, oxymethyl, ethyoxyl, phenyl, fluorine group, and pyridyl; and R2, R3, R4, and R5 cannot be hydrogen at the same time.
