6837-05-4Relevant academic research and scientific papers
Hydrogen-Bonding Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers over Ionic Liquid under Metal-Free Conditions
Wang, Huan,Zhao, Yanfei,Zhang, Fengtao,Wu, Yunyan,Li, Ruipeng,Xiang, Junfeng,Wang, Zhenpeng,Han, Buxing,Liu, Zhimin
supporting information, p. 11850 - 11855 (2020/05/16)
O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal- and solvent-free conditions. The IL 1-butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO3H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO3H-BMIm][OTf] could form three strong H-bonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., >99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.
Biological Evaluation and X-ray Co-crystal Structures of Cyclohexylpyrrolidine Ligands for Trypanothione Reductase, an Enzyme from the Redox Metabolism of Trypanosoma
De Gasparo, Raoul,Brodbeck-Persch, Elke,Bryson, Steve,Hentzen, Nina B.,Kaiser, Marcel,Pai, Emil F.,Krauth-Siegel, R. Luise,Diederich, Fran?ois
supporting information, p. 957 - 967 (2018/04/10)
The tropical diseases human African trypanosomiasis, Chagas disease, and the various forms of leishmaniasis are caused by parasites of the family of trypanosomatids. These protozoa possess a unique redox metabolism based on trypanothione and trypanothione reductase (TR), making TR a promising drug target. We report the optimization of properties and potency of cyclohexylpyrrolidine inhibitors of TR by structure-based design. The best inhibitors were freely soluble and showed competitive inhibition constants (Ki) against Trypanosoma (T.) brucei TR and T. cruzi TR and in vitro activities (half-maximal inhibitory concentration, IC50) against these parasites in the low micromolar range, with high selectivity against human glutathione reductase. X-ray co-crystal structures confirmed the binding of the ligands to the hydrophobic wall of the “mepacrine binding site” with the new, solubility-providing vectors oriented toward the surface of the large active site.
Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
supporting information, p. 6940 - 6944 (2018/05/14)
Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
Iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones to chiral diols
Yang, Xiao-Hui,Yue, Hai-Tao,Yu, Na,Li, Yi-Pan,Xie, Jian-Hua,Zhou, Qi-Lin
, p. 1811 - 1814 (2017/03/09)
We report a protocol for the highly efficient iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80-95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of (?)-preclamol and a chiral 2,5-disubstituted tetrahydropyran.
Asymmetric hydrogenation of allylic alcohols using ir?N,P-Complexes
Li, Jia-Qi,Liu, Jianguo,Krajangsri, Suppachai,Chumnanvej, Napasawan,Singh, Thishana,Andersson, Pher G.
, p. 8342 - 8349 (2018/05/23)
In this study, a series of γ,γ-disubstituted and β,γ-disubstituted allylic alcohols were prepared and successfully hydrogenated using suitable N,P-based Ir complexes. High yields and excellent enantioselectivities were obtained for most of the substrates studied. This investigation also revealed the effect of the acidity of the N,P?Ir-complexes on the acid-sensitive allylic alcohols. DFT ΔpKa calculations were used to explain the effect of the N,P-ligand on the acidity of the corresponding Ir-complex. The selectivity model of the reaction was used to accurately predict the absolute configuration of the hydrogenated alcohols.
Catalytic enantioselective ethylalumination of terminal alkenes: Substrate effects and absolute configuration assignment
Parfenova, Lyudmila V.,Kovyazin, Pavel V.,Tyumkina, Tatyana V.,Makrushina, Alyona V.,Khalilov, Leonard M.,Dzhemilev, Usein M.
, p. 124 - 135 (2015/02/19)
The chemo- and enantioselectivity of the reaction of alkenes with AlEt3 catalyzed by bis(1-neomenthylindenyl)zirconium dichloride has been studied. The reaction with linear alkenes in a chlorinated solvent (CH2Cl2) gives m
Hydroxyl-Directed Cross-Coupling: A Scalable Synthesis of Debromohamigeran e and Other Targets of Interest
Blaisdell, Thomas P.,Morken, James P.
supporting information, p. 8712 - 8715 (2015/07/27)
A hydroxyl functional group positioned β to a pinacol boronate can serve to direct palladium-catalyzed cross-coupling reactions. This feature can be used to control the reaction site in multiply borylated substrates and can activate boronates for reaction that would otherwise be unreactive.
Preparation of chiral 3-arylpyrrolidines via the enantioselective 1,4-addition of arylboronic acids to fumaric esters catalyzed by Rh(I)/chiral diene complexes
Chung, Yu-Chiang,Janmanchi, Damodar,Wu, Hsyueh-Liang
, p. 2766 - 2769 (2012/07/17)
A highly efficient rhodium-catalyzed protocol for the preparation of 2-arylsuccinic esters and 3-arylpyrrolidines of high optical purity has been achieved. In the presence of 1 mol % of a chiral diene/Rh(I) catalyst, asymmetric addition of various arylbor
Aerobic lactonization of diols by biomimetic oxidation
Endo, Yoshinori,Baeckvall, Jan-E.
supporting information; experimental part, p. 12596 - 12601 (2011/12/03)
Coming up for air: Highly efficient aerobic lactonization can be carried out by a biomimetic oxidation system based on coupled redox catalysts (ruthenium catalyst and electron transfer mediators). This system leads to a low-energy electron transfer from diol to molecular oxygen. Various diols were aerobically oxidized to the corresponding five- to nine-membered lactones in good to high yields under mild reaction conditions (see scheme).
Rhenium complex-catalyzed acylative cleavage of ethers with acyl chlorides
Umeda, Rui,Nishimura, Takashi,Kaiba, Kenta,Tanaka, Toshimasa,Takahashi, Yuuki,Nishiyama, Yutaka
experimental part, p. 7217 - 7221 (2011/10/08)
It was found that rhenium complex was an efficient catalyst for the acylative cleavage of C-O bond of ethers with acyl chlorides. When acyclic ethers were allowed to react with acyl chlorides in the presence of a catalytic amount of ReBr(CO)5, acylative cleavage of C-O bond of acyclic ethers smoothly proceeded to give the corresponding esters in moderate to good yields. Similarly, cyclic ethers were acylative cleaved by acyl chlorides to give the corresponding chloro substituted esters in good yields by the use of Re 2O7 catalyst.
