- Hydrogen-Bonding Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers over Ionic Liquid under Metal-Free Conditions
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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.
- Wang, Huan,Zhao, Yanfei,Zhang, Fengtao,Wu, Yunyan,Li, Ruipeng,Xiang, Junfeng,Wang, Zhenpeng,Han, Buxing,Liu, Zhimin
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supporting information
p. 11850 - 11855
(2020/05/16)
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- Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
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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.
- Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
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supporting information
p. 6940 - 6944
(2018/05/14)
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- Biological Evaluation and X-ray Co-crystal Structures of Cyclohexylpyrrolidine Ligands for Trypanothione Reductase, an Enzyme from the Redox Metabolism of Trypanosoma
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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.
- De Gasparo, Raoul,Brodbeck-Persch, Elke,Bryson, Steve,Hentzen, Nina B.,Kaiser, Marcel,Pai, Emil F.,Krauth-Siegel, R. Luise,Diederich, Fran?ois
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supporting information
p. 957 - 967
(2018/04/10)
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- Iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones to chiral diols
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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.
- Yang, Xiao-Hui,Yue, Hai-Tao,Yu, Na,Li, Yi-Pan,Xie, Jian-Hua,Zhou, Qi-Lin
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p. 1811 - 1814
(2017/03/09)
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- Asymmetric hydrogenation of allylic alcohols using ir?N,P-Complexes
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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.
- Li, Jia-Qi,Liu, Jianguo,Krajangsri, Suppachai,Chumnanvej, Napasawan,Singh, Thishana,Andersson, Pher G.
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p. 8342 - 8349
(2018/05/23)
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- Catalytic enantioselective ethylalumination of terminal alkenes: Substrate effects and absolute configuration assignment
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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
- Parfenova, Lyudmila V.,Kovyazin, Pavel V.,Tyumkina, Tatyana V.,Makrushina, Alyona V.,Khalilov, Leonard M.,Dzhemilev, Usein M.
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p. 124 - 135
(2015/02/19)
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- Hydroxyl-Directed Cross-Coupling: A Scalable Synthesis of Debromohamigeran e and Other Targets of Interest
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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.
- Blaisdell, Thomas P.,Morken, James P.
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supporting information
p. 8712 - 8715
(2015/07/27)
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- Preparation of chiral 3-arylpyrrolidines via the enantioselective 1,4-addition of arylboronic acids to fumaric esters catalyzed by Rh(I)/chiral diene complexes
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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
- Chung, Yu-Chiang,Janmanchi, Damodar,Wu, Hsyueh-Liang
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p. 2766 - 2769
(2012/07/17)
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- PRACTICAL METHOD FOR REDUCING ESTERS OR LACTONES
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Esters and lactones can be respectively reduced to alcohols and diols in the presence of the Group 8 (VIII) transition metal complex, base and hydrogen gas (H2). An extremely practical reduction method can be provided by preferable combinations of the Group 8 (VIII) transition metal complex, the base, a used amount of the base, a pressure of hydrogen gas and a reaction temperature. This method is used in place of hydride reduction and is a useful method by which design of highly active catalysts can be relatively easily made while a high productivity can be expected.
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Page/Page column 13
(2011/04/18)
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- Catalytic hydrogenation of carboxamides and esters by well-defined Cp*Ru complexes bearing a protic amine ligand
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A novel catalytic method for the straightforward hydrogenation of carboxamides and esters to primary alcohols has been developed. Chiral modification in the ligand sphere of the well-defined Cp*Ru catalyst molecule opens up a new possibility for the development of an enantioselective hydrogenation of racemic substrates via dynamic kinetic resolution.
- Ito, Masato,Ootsuka, Takashi,Watari, Ryo,Shiibashi, Akira,Himizu, Akio,Ikariya, Takao
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supporting information; experimental part
p. 4240 - 4242
(2011/06/21)
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- Aerobic lactonization of diols by biomimetic oxidation
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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).
- Endo, Yoshinori,Baeckvall, Jan-E.
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supporting information; experimental part
p. 12596 - 12601
(2011/12/03)
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- Rhenium complex-catalyzed acylative cleavage of ethers with acyl chlorides
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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.
- Umeda, Rui,Nishimura, Takashi,Kaiba, Kenta,Tanaka, Toshimasa,Takahashi, Yuuki,Nishiyama, Yutaka
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experimental part
p. 7217 - 7221
(2011/10/08)
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- Pd-catalyzed enantioselective allyl-allyl cross-coupling
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The Pd-catalyzed cross-coupling of allylic carbonates and allylB(pin) is described. The regioselectivity of this reaction is sensitive to the bite angle of the ligand, with small-bite-angle ligands favoring the branched substitution product. This mode of
- Zhang, Ping,Brozek, Laura A.,Morken, James P.
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supporting information; scheme or table
p. 10686 - 10688
(2010/11/04)
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- Highly site- and enantioselective Cu-catalyzed allylic alkylation reactions with easily accessible vinylaluminum reagents
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An efficient method for catalytic asymmetric allylic alkylation (AAA) of allylic phosphates with vinylaluminum reagents is reported. The vinylmetal reagents are prepared by reaction of commercially available DIBAL-H and a terminal alkyne. The resulting vi
- Lee, Yunmi,Akiyama, Katsuhiro,Gillingham, Dennis G.,Brown, M. Kevin,Hoveyda, Amir H.
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p. 446 - 447
(2008/09/20)
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- HETEROCYCLIC ARYLSULPHONES SUITABLE FOR TREATING DISORDERS THAT RESPOND TO MODULATION OF THE SEROTONIN 5HT6 RECEPTOR
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The invention relates to compounds of the formula (I) wherein the variables have meanings given in the claims and the description. The invention also relates to the use of a compound of the formula (I) or a pharmaceutically acceptable salt thereof for pre
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Page/Page column 143-144; 158-159
(2008/06/13)
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- Enantioselective ene reaction of cyclopentadiene and α,β-enals catalyzed by a diphenylprolinol silyl ether
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(Chemical Equation Presented) The opposite result: A diphenylprolinol silyl ether promotes an intermolecular enantioselective ene reaction of α,β-enals with cyclopentadiene. This is the first example of cyclopentadiene acting as the ene component, and not
- Gotoh, Hiroaki,Masui, Ryouhei,Ogino, Hiroshi,Shoji, Mitsuru,Hayashi, Yujiro
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p. 6853 - 6856
(2007/10/03)
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- HETEROCYCLIC COMPOUNDS SUITABLE FOR TREATING DISORDERS THAT RESPOND TO MODULATION OF THE DOPAMINE D3 RECEPTOR
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The invention relates to compounds of the formula (I) wherein n is 0, 1 or 2; G is CH2 or CHR3; R1 is H, C,-C6-alkyl, C,-C6-alkyl substituted by C3-C6-cycloalkyl, Cl-C6-hydroxyalkyl, fluorinated C,-C6-alkyl, C3-C6-cycloalkyl, fluorinated C3-C6-cycloalkyl, C3-C6- alkenyl, fluorinated C3-C6-alkenyl, formyl, acetyl or propionyl; R2, R3 and R4 are, independently of each other, H, methyl, fluoromethyl, difluoromethyl, or trifluoromethyl; A is phenylene, pyridylene, pyrimidylene, pyrazinylene, pyridazinylene or thiophenylene, which can be substituted by one ore more substituents selected from halogen, methyl, methoxy and CF3; E is NR5 or CH2, wherein R5 is H or C1 -C3-alkyl; Ar is a cyclic radical selected from the group consisting of phenyl, a 5- or 6- -membered heteroaromatic radical comprising as ring members 1, 2 or 3 heteroatoms selected from N, O and S and a phenyl ring fused to a saturated or unsaturated 5- or 6-membered carbocyclic or heterocyclic ring, where the heterocyclic ring comprises as ring members 1, 2 or 3 heteroatoms selected from N, O and S and/or 1, 2 or 3 heteroatom-containing groups each independently selected from NR8, where R8 is H, C1-C4-alkyl, fluorinated C1-C4-alkyl, C1-C4-alkylcarbonyl or fluorinated C1-C4-alkylcarbonyl, and where the cyclic radical Ar may carry 1, 2 or 3 substituents Ra, wherein the variable Ra has the meanings given in the claims and in the description; and physiologically tolerated acid addition salts thereof. The invention also relates to the use of a compound of the formula I or a pharmaceutically acceptable salt thereof for preparing a pharmaceutical composition for the treatment of a medical disorder susceptible to treatment with a dopamine D3 receptor ligand.
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Page/Page column 108
(2010/11/08)
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- Catalytic enantioselective hydrogenation of vinyl bis(boronates)
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Catalytic enantioselective hydrogenation of prochiral vinylmetallic reagents can provide an attractive alternative to hydrometalation and bismetalation of alkenes. In this contribution, the first highly enantioselective hydrogenation of vinyl boronic esters is described. The chiral reduction products are versatile intermediates for chemical synthesis. Copyright
- Morgan, Jeremy B.,Morken, James P.
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p. 15338 - 15339
(2007/10/03)
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- Chiral norbornadienes as efficient ligands for the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds
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(Chemical Equation Presented) A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds has been developed. While phosphorus-based chiral ligands fail to induce high stereoselectivity, chiral norbornadiene ligands have proved to be uniquely effective to achieve high enantioselectivity in these 1,4-addition reactions.
- Shintani, Ryo,Ueyama, Kazuhito,Yamada, Ichiro,Hayashi, Tamio
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p. 3425 - 3427
(2007/10/03)
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- Cp*Ir complex-catalyzed N-heterocyclization of primary amines with diols: A new catalytic system for environmentally benign synthesis of cyclic amines
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(Chemical Equation Presented) A new efficient method for the N-heterocyclization of primary amines with diols catalyzed by a Cp*Ir complex was developed. A variety of five-, six-, and seven-membered cyclic amines were synthesized in good to excellent yields with the formation of only water as a byproduct. A two-step asymmetric synthesis of (S)-2-phenylpiperidine was also achieved using (R)-1-phenylethylamine as a starting primary amine.
- Fujita, Ken-Ichi,Fujii, Takeshi,Yamaguchi, Ryohei
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p. 3525 - 3528
(2007/10/03)
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- Enantioselective 1,4-addition of aromatic nucleophiles to alpha,beta-unsaturated aldehydes using chiral organic catalysts
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Nonmetallic, chiral organic catalysts are used to catalyze the 1,4-addition of an aromatic nucleophile to an α,β-unsaturated aldehyde. The aromatic nucleophile may be an N,N-disubstituted aniline compound, or an analog thereof. The reaction is efficient a
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- Claisen rearrangements of allylic and propargylic alcohols prepared by an N-Boc-2-acyloxazolidine methodology - Application to the synthesis of original chiral building blocks
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Stereodefined alkenols prepared in two steps from a Weinreb amide derived from (R)-phenylglycinol undergo highly stereoselective Claisen rearrangements. The masked aldehyde moiety of the produced N-Boc-alkenyloxazolidines can then be recovered and reduced without epimerization, to yield new enantiopure chiral building blocks. Alternatively, epoxidation of these N-Boc-2-alkenyloxazolidines by a well-established intramolecular bromocarbamation involving the Boc protecting group occurs stereoselectively. The resulting α,β-epoxyoxazolidines are then transformed into trisubstituted stereodefined cyclopropanes. Claisen rearrangements of propargylic alcohols, on the other hand, stereoselectively give α-allenyloxazolidines. These compounds follow a different pathway to α-alkenyloxazolidines as regards bromocarbamation. An original route to enantiopure 3-hydroxy-4-phenylpiperidine was found in the course of this study.
- Agami, Claude,Couty, Francois,Evano, Gwilherm
-
-
- Claisen rearrangement of allylic alcohols prepared through N-Boc-2-acyloxazolidine methodology. Application to the synthesis of trisubstituted cyclopropanes
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Stereodefined allylic alcohols prepared from a (R)-phenylglycinol-derived Weinreb amide undergo a Claisen rearrangement with a high level of stereocontrol. The produced N-Boc-2-alcenyloxazolidines can be either hydrolyzed to afford enantiomerically enriched enals or further epoxidized using a two-step sequence. The resulting epoxyoxazolidines can then be transformed into trisubstituted cyclopropanes. (C) 2000 Elsevier Science Ltd.
- Agami,Couty,Evano
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p. 8301 - 8305
(2007/10/03)
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- Acyclic phenylalkanediols as substrates for the study of enzyme recognition: Synthesis of substrates and enzymatic resolution via hydrolysis and transesterification
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Different racemic or prochiral phenyl alkane (1,n)-diols were synthesized, and their resolution was carried out by two different strategies: enzymatic transesterification with vinyl acetate, or enzymatic hydrolysis of their corresponding diacetates, in both cases catalysed by porcine pancreatic lipase (PPL). The absolute configuration of the optically enriched reaction products was determined by formation of Mosher's esters or by the use of the Benzene Sector and Benzene Chirality Rules as obtained from the Circular Dichroism spectra.
- Rumbero, Angel,Borreguero, Isabel,Sinisterra, Jose V.,Alcantara, Andres R.
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p. 14947 - 14960
(2007/10/03)
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- TETRAHYDROISOQUINOLINES AS ALPHA-2 ANTAGONISTS AND BIOGENIC AMINE UPTAKE INHIBITORS
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The present invention provides a tetrahydroisoquinoline compound of the formula STR1 or a pharmaceutically acceptable salt thereof which is an antagonist for alpha-2 adrenoreceptors and/or which inhibits biogenic amine uptake.
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- Regio- and Enantioselective Properties of the Lipase-catalyzed Irreversible Transesterification of Some 2-Substituted-1,4-Butanediols in Organic Solvents
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The regioselectivity of the Pseudomonas fluorescens (P. cepacia) lipase (PFL)-catalyzed irreversible transesterification of 2-substituted-1,4-butanediols 1a-3a has been studied and, in the case of 3a, it has been shown that (R)- and (S)-diols are acylated
- Ferraboschi, Patrizia,Casati, Silvana,Verza, Elisa,Santaniello, Enzo
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p. 1027 - 1030
(2007/10/02)
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- ENANTIOSELEKTIVE KATALYSE, 63 - OPTISCH AKTIVE PHOSPHINE AUS DICARBONSAEUREN UND IHR EINSATZ IN DER ENANTIOSELEKTIVEN HYDRIERUNG
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Two optically active bident phosphine ligands were synthesized from derivatives of succinic acid as starting materials.The optical resolution of the acids was carried out with cinchonidine and (S)-α-phenylethylamine.In the Rh-catalyzed enantioselective hydrogenation of α-acetamidocinnamic acid, the bisphosphine with a phenyl substituent in the 2-position of the four-carbon chain gave enantiomeric excess of 17percent.The enantiomeric excess was twice as high with the corresponding thienyl substituted biphosphine.
- Brunner, H.,Zettlmeier, W.
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p. 259 - 265
(2007/10/02)
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- SYNTHESE CHIRALER PHOSPHINOXIDE UND PHOSPHINE DURCH MICHAELIS-ARBUZOV-UMLAGERUNG
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Several phosphinites and phosphites, derived from chiral alcohols, were synthesized.The phosphinites were subjected to a I2-catalyzed Michaelis-Arbuzov rearrangement.Phosphinites derived from primary alcohols give satisfactory yields of the corresponding phosphineoxides.Phosphinites synthesized from secondary alcohols also undergo the rearrangement but numerous byproducts appear in the reaction mixtures.Optical resolutions of chiral phosphineoxides by crystallization with optically active acids were not successful.The corresponding phosphines can easily be prepared by reduction of the oxides with trichlorosilane.
- Brunner, H.,Zettlmeier, W.
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p. 247 - 257
(2007/10/02)
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- Studies on the Autoxidation of 1-Phenylbuta-1,3-diene and 2-Phenylbuta-1,3-diene
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Hydrogenation of the polymeric peroxides formed during the autoxidation of 1-phenylbuta-1,3-diene (1) and 2-phenylbuta-1,3-diene (10) at 50 deg C in an autoclave yielded 1-phenylbutane-3,4-diol (5) and 2-phenylbutane-1,4-diol(12), respectively.The LiAlH4 reduction of 1-phenylbuta-1,3-diene oxidate (50 deg C) yielded cinnamyl alcohols (4) as a major product.The oxygen-containing polymeric products formed along with Diels-Alder dimers during the oxidation of the title substances at 140 deg C showed no degradation after subjecting to hydrogenation and are therefore considered as polyethers.
- Blau, K.,Voerkel,V.,Willecke, L.
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- Inhibition of Liver Alcohol Dehydrogenase and Ethanol Metabolism by 3-Substituted Thiolane 1-Oxides
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3-Substituted thiolane oxides (methyl, n-butyl, n-hexyl, and phenyl) were prepared and tested as inhibitors of horse, monkey, and rat liver alcohol dehydrogenases and of ethanol metabolism in rats.These compounds inhibit alcohol oxidation in an uncompetit
- Chadha, Vijay K.,Leidal, Kevin G.,Plapp, Bryce V.
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- SYNTHESIS OF 1-SUBSTITUTED (S)-4-ACETOXY-1-PENTEN-3-ONES USING (S)-LACTIC ACID AS A CHIRAL SOURCE AND THEIR SYNTHETIC REACTIONS
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Ylide reaction of (S)-3-acetoxy-1-triphenylphosphoranylidene-2-butanone, derived from (S)-lactic acid, with aldehydes gives 1-substituted (S)-4-acetoxy-1-penten-3-one derivatives, which are shown to be transformed into useful chiral compouds by stereosele
- Hiyama, Tamejiro,Kobayashi, Kumi,Fujita, Makoto
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p. 4959 - 4962
(2007/10/02)
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- Reductive Rearrangement of 4-Phenyl-1,3-dioxans to 2-Phenylbutane-1,4-diols upon Treatment with Sodium-Potassium Alloy
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Reduction of 4-phenyl-1,3-dioxan with Na-K alloy affords 2-phenylbutane-1,4-diol as the major product along with smaller amounts of 3-phenylpropan-1-ol and 3,4-diphenylhexane-1,6-diols.
- Bailey, William F.,Cioffi, Eugene A.
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p. 155 - 156
(2007/10/02)
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