87802-71-9Relevant articles and documents
Tandem Iridium Catalysis as a General Strategy for Atroposelective Construction of Axially Chiral Styrenes
He, Ying,Liu, Peng,Min, Xiao-Long,Qi, Xiaotian,Wang, Jie,Yi, Wenbin
supporting information, p. 10686 - 10694 (2021/07/26)
Axially chiral styrenes are of great interest since they may serve as a class of novel chiral ligands in asymmetric synthesis. However, only recently have strategies been developed for their enantioselective preparation. Thus, the development of novel and efficient methodologies is highly desirable. Herein, we reported the first tandem iridium catalysis as a general strategy for the synthesis of axially chiral styrenes enabled by Asymmetric Allylic Substitution-Isomerization (AASI) using cinnamyl carbonate analogues as electrophiles and naphthols as nucleophiles. In this approach, axially chiral styrenes were generated through two independent iridium-catalytic cycles: iridium-catalyzed asymmetric allylic substitution and in situ isomerization via stereospecific 1,3-hydride transfer catalyzed by the same iridium catalyst. Both experimental and computational studies demonstrated that the isomerization proceeded by iridium-catalyzed benzylic C-H bond oxidative addition, followed by terminal C-H reductive elimination. Amid the central-to-axial chirality transfer, the hydroxyl of naphthol plays a crucial role in ensuring the stereospecificity by coordinating with the Ir(I) center. The process accommodated broad functional group compatibility. The products were generated in excellent yields with excellent to high enantioselectivities, which could be transformed to various axially chiral molecules.
Ternary Catalysis Enabled Three-Component Asymmetric Allylic Alkylation as a Concise Track to Chiral α,α-Disubstituted Ketones
Chang, Wenju,Fu, Xiang,Hu, Wenhao,Kang, Zhenghui,Liang, Yong,Tian, Xue,Xu, Xinfang,Zhao, Wenxuan
, p. 20818 - 20827 (2021/12/17)
Multicomponent reactions that involve interception of onium ylides through Aldol, Mannich, and Michael addition with corresponding bench-stable acceptors have demonstrated broad applications in synthetic chemistry. However, because of the high reactivity and transient survival of these in situ generated intermediates, the substitution-type interception process, especially the asymmetric catalytic version, remains hitherto unknown. Herein, a three-component asymmetric allylation of α-diazo carbonyl compounds with alcohols and allyl carbonates is disclosed by employing a ternary cooperative catalysis of achiral Pd-complex, Rh2(OAc)4, and chiral phosphoric acid CPA. This method represents the first example of three-component asymmetric allylic alkylation through an SN1-type trapping process, which involves a convergent assembly of two active intermediates, Pd-allyl species, and enol derived from onium ylides, providing an expeditious access to chiral α,α-disubstituted ketones in good to high yields with high to excellent enantioselectivity. Combined experimental and computational studies have shed light on the mechanism of this novel three-component reaction, including the critical role of Xantphos ligand and the origin of enantioselectivity.
Ultrasound irradiation as an effective tool in synthesis of the slag-based catalysts for carboxymethylation
Kholkina, Ekaterina,Kumar, Narendra,Er?nen, Kari,Peurla, Markus,Palonen, Heikki,Salonen, Jarno,Lehtonen, Juha,Murzin, Dmitry Yu.
, (2021/03/06)
Waste minimization strategy was applied in the current work for synthesis of the catalysts from industrial solid waste, namely desulfurization slag. The starting slag material comprising CaCO3, Ca(OH)2, SiO2, Al2O3, Fe2O3, and TiO2 was processed by various treating agents systematically varying the synthesis parameters. A novel efficient technique – ultrasound irradiation, was applied as an additional synthesis step for intensification of the slag dissolution and crystallization of the new phases. Physico-chemical properties of the starting materials and synthesized catalysts were evaluated by several analytical techniques. Treatment of the industrial slag possessing initially poor crystal morphology and a low surface area (6 m2/g) resulted in formation of highly-crystalline catalysts with well-developed structural properties. Surface area was increased up to 49 m2/g. High basicity of the neat slag as well as materials synthesized on its basis makes possible application of these materials in the reactions requiring basic active sites. Catalytic performance of the synthesized catalysts was elucidated in the synthesis of carbonate esters by carboxymethylation of cinnamyl alcohol with dimethyl carbonate carried out at 150 °C in a batch mode. Ultrasonication of the slag had a positive effect on the catalytic activity. Synthesized catalysts while exhibiting similar selectivity to the desired product (ca. 84%), demonstrated a trend of activity increase for materials prepared using ultrasonication pretreatment. The choice of the treating agent also played an important role in the catalytic performance. The highest selectivity to the desired cinnamyl methyl carbonate (88%) together with the highest activity (TOF35 = 3.89*10?7 (mol/g*s)) was achieved over the material synthesized using 0.6 M NaOH solution as the treating agent with the ultrasound pre-treatment at 80 W for 4 h.
Regioselective Wacker-Type Oxidation of Internal Olefins in tBuOH Using Oxygen as the Sole Oxidant and tBuONO as the Organic Redox Cocatalyst
Huang, Qing,Li, Ya-Wei,Ning, Xiao-Shan,Jiang, Guo-Qing,Zhang, Xiao-Wei,Qu, Jian-Ping,Kang, Yan-Biao
supporting information, p. 965 - 969 (2020/02/15)
A regioselective Wacker-Tsuji oxidation of internal olefins in tBuOH has been developed using oxygen as the terminal oxidant and tert-butyl nitrite as the simple organic redox cocatalyst without the involvement of hazardous cocatalysts or harsh reaction conditions. A series of internal olefins bearing various functional groups can be oxidized to the corresponding substituted ketones in generally good yields with high regioselectivities.
Pd/BIPHEPHOS is an Efficient Catalyst for the Pd-Catalyzed S-Allylation of Thiols with High n-Selectivity
Schlatzer, Thomas,Schr?der, Hilmar,Trobe, Melanie,Lembacher-Fadum, Christian,Stangl, Simon,Schl?gl, Christoph,Weber, Hansj?rg,Breinbauer, Rolf
supporting information, p. 331 - 336 (2019/11/16)
The Pd-catalyzed S-allylation of thiols with stable allylcarbonate and allylacetate reagents offers several advantages over established reactions for the formation of thioethers. We could demonstrate that Pd/BIPHEPHOS is a catalyst system which allows the transition metal-catalyzed S-allylation of thiols with excellent n-regioselectivity. Mechanistic studies showed that this reaction is reversible under the applied reaction conditions. The excellent functional group tolerance of this transformation was demonstrated with a broad variety of thiol nucleophiles (18 examples) and allyl substrates (9 examples), and could even be applied for the late-stage diversification of cephalosporins, which might find application in the synthesis of new antibiotics. (Figure presented.).
Enantioselective α-functionalization of 1,3-dithianes by iridium-catalyzed allylic substitution
Xie, Xingang,Tang, Shouchu,Wang, Xiaolei,Wang, Panpan,Jiang, Qian,Zhao, Ruibo
, p. 12456 - 12467 (2020/11/09)
An iridium-catalyzed asymmetric allylic substitution reaction with 2-alkoxy carbonyl-1,3-dithianes has been achieved with high regio- and enantioselectivities. The transformation provides a new method for the enantioselective α-functionalization of dithianes. The corresponding dithiane-containing products are easily converted into many other derivatives with high yields and enantioselectivities.
Stereoselective Modification of N-(α-Hydroxyacyl)-glycinesters via Palladium-Catalyzed Allylic Alkylation
Horn, Alexander,Kazmaier, Uli
supporting information, p. 4595 - 4599 (2019/06/27)
N-(α-Hydroxyacyl)-glycinesters can be used as excellent nucleophiles in Pd-catalyzed allylic alkylation. The method allows for the stereoselective introduction of a wide range of side chains, including highly functionalized ones. Both diastereomers can be accessed through variation of the reaction conditions. Furthermore, the use of stannylated carbonates introduces vinylstannane motifs, which are eligible for subsequent C-C coupling reactions.
Synthesis of Carbonate Esters by Carboxymethylation Using NaAlO2 as a Highly Active Heterogeneous Catalyst
Ramesh, Sreerangappa,Indukuri, Kiran,Riant, Olivier,Debecker, Damien P.
, p. 1846 - 1851 (2019/01/04)
Sodium aluminate is presented as a highly active heterogeneous catalyst that is able to convert a range of alcohols into the corresponding unsymmetrical carbonate esters by reaction with dimethyl carbonate. Preparing NaAlO2 via spray drying boosts the basic properties and the activity of the catalyst.
Stereodivergent Allylation of Azaaryl Acetamides and Acetates by Synergistic Iridium and Copper Catalysis
Jiang, Xingyu,Boehm, Philip,Hartwig, John F.
supporting information, p. 1239 - 1242 (2018/02/09)
We report stereodivergent allylic substitution reactions of allylic esters with prochiral enolates derived from azaaryl acetamides and acetates to form products from addition of the enolates at the most substituted carbon of an allyl moiety with two catalysts, a chiral metallacyclic iridium complex and a chiral bisphosphine-ligated copper(I) complex, which individually control the configuration of the electrophilic and nucleophilic carbon atoms, respectively. By simple permutations of enantiomers of the two catalysts, all four stereoisomers of products containing two stereogenic centers were synthesized individually with high diastereoselectivity and enantioselectivity. A variety of azaaryl acetamides and acetates bearing pyridyl, benzothiazolyl, benzoxazolyl, pyrazinyl, quinolinyl and isoquinolinyl moieties were all found to be suitable for this transformation.
Nickel-Catalyzed Reductive Allylation of Tertiary Alkyl Halides with Allylic Carbonates
Chen, Haifeng,Jia, Xiao,Yu, Yingying,Qian, Qun,Gong, Hegui
supporting information, p. 13103 - 13106 (2017/09/19)
The construction of all C(sp3) quaternary centers has been successfully achieved under Ni-catalyzed cross-electrophile coupling of allylic carbonates with unactivated tertiary alkyl halides. For allylic carbonates bearing C1 or C3 substituents, the reaction affords excellent regioselectivity through the addition of alkyl groups to the unsubstituted allylic carbon terminus. The allylic alkylation method also exhibits excellent functional-group compatibility, and delivers the products with high E selectivity.
