- Synthesis of - and -Bisferrocenyl> Diselenides and Their Application to Asymmetric Selenoxide Elimination and Sigmatropic Rearrangement
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Novel optically-active bisferrocenyl> diselenides ( and ), each of which possesses two axial and two central elements of chirality, have been prepared by lithiation of commercially available chiral ferrocenes, followed by reaction with elemental selenium and air oxidation, in 77-80percent isolated yields.The structure of the -bisferrocenyl diselenide has been fully characterized by X-ray crystallography.Six chiral ferrocenyl vinylic selenides and six chiral allylic ferrocenyl selenides have been newly prepared by reaction of the diselenides with the corresponding propiolate derivatives and allylic halides.The oxidation of the vinylic selenides with m-chloroperbenzoic acid in various organic solvents produces axially chiral allenecarboxylic esters via asymmetric selenoxide elimination in 27-59percent chemical yields with high enantioselectivities (up to 89percent ee).Similar treatment of the allylic selenides afforded the corresponding chiral allylic alcohols via asymmetric sigmatropic rearrangement in 28-82percent chemical yields with high enantioselectivities (up to 89percent ee).The observed high enantioselectivities indicate that oxidation proceeds diastereoselectively, that the resultant chiral selenoxides are slow to racemize, and also that selenoxide elimination and sigmatropic rearrangement proceed with little loss of optical activity.
- Nishibayashi, Yoshiaki,Singh, Jai Deo,Fukuzawa, Shin-ichi,Uemura, Sakae
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- Asymmetric [2,3]sigmatropic rearrangement of optically active allylic selenides
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Oxidation of an optically active allylic selenide derived from L-proline 1 with m-chloroperbenzoic acid afforded the corresponding chiral allylic alcohol 3 via asymmetric [2,3]sigmatropic rearrangement with fair enantioselectivity (up to 66% e.e.).
- Fujita, Ken-Ichi,Kanakubo, Mitsuhiro,Ushijima, Hirobumi,Oishi, Akihiro,Ikeda, Yoshikazu,Taguchi, Yoichi
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- Characterization of a Self-Sufficient Cytochrome P450 Monooxygenase from Deinococcus apachensis for Enantioselective Benzylic Hydroxylation
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A self-sufficient cytochrome P450 monooxygenase from Deinococcus apachensis (P450DA) was identified and successfully overexpressed in Escherichia coli BL21(DE3). P450DA would be a member of the CYP102D subfamily and assigned as CYP102D2 according to the phylogenetic tree and sequence alignment. Purification and characterization of the recombinant P450DA indicated both NADH and NADPH could be used by P450DA as a reducing cofactor. The recombinant E. coli (P450DA) strain was functionally active, showing excellent enantioselectivity for benzylic hydroxylation of methyl 2-phenylacetate. Further substrate scope studies revealed that P450DA is able to catalyze benzylic hydroxylation of a variety of compounds, affording the corresponding chiral benzylic alcohols in 86–99 % ee and 130–1020 total turnover numbers.
- Xie, Lingzhi,Chen, Ke,Cui, Haibo,Wan, Nanwei,Cui, Baodong,Han, Wenyong,Chen, Yongzheng
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- Asymmetric [2,3] sigmatropic rearrangement via chiral selenoxide with Sharpless oxidants
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The Sharpless oxidation of some aryl cinnamyl selenides afforded a chiral 1-phenyl-2-propen-1-ol via asymmetric [2,3] sigmatropic rearrangement in a moderate to high enantiomeric excess (up to 92% e.e.). The enantioselectivity was found to be enhanced remarkably by the introduction of the o-nitro group to an arylseleno moiety of the substrate and the use of diisopropyl tartrate (DIPT) ligand in the Sharpless oxidant. In the rearrangement step two possible transition states (TS(exo) and TS(endo)) are conceivable in which TS(endo) was revealed to be more stable by 4.2 kcal/mol than TS(exo) from the extended-Huckel calculation.
- Komatsu,Nishibayashi,Uemura
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- Enantioselective benzylic hydroxylation with pseudomonas monteilii TA-5: A simple method for the syntheses of (R)-benzylic alcohols containing reactive functional groups
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Highly enantioselective benzylic hydroxylations of benzene derivatives (1-4) containing reactive functional groups were achieved for the first time with Pseudomonas monteilii TA-5 as biocatalyst, giving the corresponding (R)-benzylic alcohols 5-8 in 93-99% ee as the only products. Preparative biotransformations were demonstrated by the biohydroxylation of 1 and 2 with resting cells of P monteilii TA-5 to afford (R)-5 in 94% ee and 66% yield and (R)-6 in 94% ee and 56% yield, respectively. The highly enantioselective biohydroxylations represent a simple access to (R)-benzylic alcohols containing reactive functional groups that are useful pharmaceutical intermediates and versatile chiral building blocks.
- Chen, Yongzheng,Lie, Felicia,Li, Zhi
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- One-pot transformation of p-toluenesulfonates of 2,3-epoxy alcohols into allylic alcohols
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A convenient and efficient method for the synthesis of synthetically useful non-racemic allylic alcohols from 4-methylbenzenesulfonates of non- racemic 2,3-epoxy alcohols is described. Satisfactory yields are obtained by treatment of 4-methylbenzenesulfonates of non-racemic 2,3-epoxy alcohols with potassium iodide followed by zinc powder and ammonium chloride in a one-pot manner. The method has been successfully applied to the synthesis of a key building block of C30-C37 botryococcenes.
- Habashita, Hiromu,Kawasaki, Takeshi,Akaji, Masako,Tamamura, Hirokazu,Kimachi, Tetsutaro,Fujii, Nobutaka,Ibuka, Toshiro
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- Enantioselective Synthesis of Cinnamyl-1-Phenyl-2-Propenyl Ether: A Metabolite of Marine Green Algal Species Caulerpa Racemosa
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The enantioselective synthesis of title compound has been achieved using a new enzyme acyl system and a mild PT catalysed etherification.The absolute configuration of natural compound has been established as R-(+) by 1H NMR analysis of MTPA esters of the
- Mallavadhani, U. V.,Rao, Y. R.
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- Microscale determination of the absolute configuration of α-aryl- substituted alcohols by the CD exciton chirality method
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The absolute configurations of a broad spectrum of aryl alcohols 1 have been determined for the first time by the CD exciton chirality method. The configurational assignment is additionally verified by computer modeling and lipase-catalyzed acetylation of the racemic alcohols. The CD-spectroscopic data have revealed that the S enantiomers of the benzoate derivatives 2 display a positive first Cotton effect and the R enantiomers a negative one at around 228 nm. Thus, the sense of the first Cotton effect of the benzoate derivative 2 allows a reliable assignment of the absolute configuration of the corresponding alcohol 1.
- Adam, Waldemar,Lukacs, Zoltan,Viebach, Kirsten,Humpf, Hans-Ulrich,Saha-Moeller, Chantu R.,Schreier, Peter
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- Enantioselective Preparation of sec. Alcohols from Aldehydes and Dialkyl Zinc Compounds, Generated in situ from Grignard Reagents, Using Substoichiometric Amounts of TADDOL-Titanates
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Using the Schlenk trick (precipitation of MgX2 from etheral solutions by the addition of 1,4-dioxane) mixtures of a Grignard reagent RMgX (X = Cl, Br, I) and 0.5 equiv.ZnCl2 in Et2O can be converted to zinc alkyls R2Zn which in turn are added with enantioselectivities of up to 99:1 to aliphatic and aromatic aldehydes in the presence of Ti(OCHMe2)4 and a chiral titanate derived from an α,α,α',α'-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL).Grignard reagents containing remote double bonds, benzene rings, or acetal groups can also be employed.Different TADDOLs are compared with respect to their usefulness in this kind of enantioselective reactions.
- Bussche-Huennefeld, Joanna Linda v.,Seebach, Dieter
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- A Chiral Metal-Organic Material that Enables Enantiomeric Identification and Purification
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We show that CMOM-3S, a previously unreported porous crystalline metal-organic material that exhibits intrinsic homochirality, serves as a general-purpose chiral crystalline sponge (CCS) and a chiral stationary phase (CSP) for gas chromatography (GC). The properties of CMOM-3S are enabled by nano-sized channels connected to adaptable molecular recognition sites that mimic enzyme-binding sites. Further, CMOM-3S is composed of inexpensive components, facile to prepare, and requires only trace amounts of analyte. When coupled with the thermal and hydrolytic stability of CMOM-3S, these features mean that a coated fused silica capillary column in which CMOM-3S serves as a CSP is both more versatile and more robust than three benchmark commercial columns. That the enantiomer with the longer GC retention time is consistently captured in CCS experiments enables CMOM-3S to serve as a powerful tool to enable both chiral purification and enantiomer identification.
- Zhang, Shi-Yuan,Yang, Cheng-Xiong,Shi, Wei,Yan, Xiu-Ping,Cheng, Peng,Wojtas, Lukasz,Zaworotko, Michael J.
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- Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition of 1,6-Enynes with Racemic Secondary Allylic Alcohols through Kinetic Resolution
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It has been established that a cationic rhodium(I)/P-phos complex catalyzes the asymmetric [2+2+2] cycloaddition of 1,6-enynes with racemic secondary allylic alcohols to produce the corresponding chiral bicyclic cyclohexenes, possessing three stereogenic
- Suzuki, Shunsuke,Shibata, Yu,Tanaka, Ken
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- Pseudomonas sp. Lipase Immobilized on Magnetic Porous Polymer Microspheres as an Effective and Recyclable Biocatalyst for Resolution of Allylic Alcohols
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Magnetic porous polymeric microspheres containing epoxy groups were prepared by suspension polymerization (denoted as magnetic Fe3O4@GEM microspheres). Fe3O4@GEM with a specific surface area of 30.41 m2/g, average pore diameter of 17.13 nm, and pore volume of 0.13 cm3/g exhibited superparamagnetic behavior with the saturation magnetization of 7.1 emu/g. The content of epoxy groups on Fe3O4@GEM was 0.22 mmol/g. Pseudomonas sp. lipase (PSL) was covalently immobilized onto the Fe3O4@GEM microspheres through the reaction between the amino groups of the enzyme and the epoxy groups on the microspheres. PSL/Fe3O4@GEM exhibited enhanced enantioselectivity for the resolution of allylic alcohol to the corresponding optically active (S)-allylic alcohol and (R)-allylic alcohol acetate compared to free PSL. The enantiomeric excess of (S)-l-pheny-2-propen-1-ol for the former (98.1%) was 81.7 times that of the latter (1.2%) when the immobilized PSL was used for transesterification resolution of (R,S)-l-pheny-2-propen-1-ol. Furthermore, the ees and eep values were still retained at 95.2% and 95.4% after PSL/Fe3O4@GEM was recycled 10 times, indicating that PSL/Fe3O4@GEM had very good reusability. In addition, the transesterification resolution of (R,S)-1-(4-methylphenyl)-2-propen-1-ol and (R,S)-1-(4-bromophenyl)-2-propen-1-ol was catalyzed by PSL/Fe3O4@GEM, affording ideal ees and eep values of 99.3%, 97.4% and 99.6%, 98.2%, respectively. Therefore, PSL/Fe3O4@GEM demonstrated its potential as a highly efficient enzymatic reactor and Fe3O4@GEM would be very promising carriers for immobilizing enzymes in industrial application.
- Gu, Yaohua,Xue, Ping
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- A KINETIC RESOLUTION OF RACEMIC EPOXIDES BY A CHIRAL LITHIUM AMIDE
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A kinetic resolution of cis-disubstituted epoxides was effectively achieved by a chiral lithium amide, prepared from (S)-2-(pyrrolidin-1-yl)-methylpyrrolidine.
- Asami, Masatoshi,Kanemaki, Noriko
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- (S)-Selective kinetic resolution and chemoenzymatic dynamic kinetic resolution of secondary alcohols
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(S)-Selective kinetic resolution was achieved through the use of a commercially available protease, which was activated with a combination of two different surfactants. The kinetic resolution (KR) process was optimized with respect to activation of the protease and to the acyl donor. The KR proved to be compatible with a range of functionalized sec-alcohols, giving good to high enantiomeric ratio values (up to >200). The enzymatic resolution was combined with a ruthenium-catalyzed racemization to give an (S)-selective dynamic kinetic resolution (DKR) of sec-alcohols. The DKR process works under very mild reaction conditions to give the corresponding esters in high yields and with excellent enantioselectivities.
- Boren, Linnea,Martin-Matute, Belen,Xu, Yongmei,Cordova, Armando,Baeckvall, Jan-E.
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- Enantioselective Allylation of Alkenyl Boronates Promotes a 1,2-Metalate Rearrangement with 1,3-Diastereocontrol
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Alkenyl boronates add to Ir(π-allyl) intermediates with high enantioselectivity. A 1,2-metalate shift forms a second C-C bond and sets a 1,3-stereochemical relationship. The three-component coupling provides tertiary boronic esters that can undergo multiple additional functionalizations. An extension to trisubstituted olefins sets three contiguous stereocenters.
- Davis, Colton R.,Luvaga, Irungu K.,Ready, Joseph M.
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supporting information
p. 4921 - 4927
(2021/05/04)
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- Highly efficient kinetic resolution of aryl-alkenyl alcohols by ru-catalyzed hydrogen transfer
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No matter through asymmetric reduction of ketones or kinetic resolution of secondary alcohols, enantioselective synthesis of the corresponding secondary alcohols is challenging when the two groups attached to the prochiral or chiral centers are spatially
- Jin, Ming Yu,Tao, Guanyu,Xing, Xiangyou,You, Yipeng
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supporting information
(2021/12/24)
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- An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
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The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
- Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
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p. 8042 - 8048
(2020/09/21)
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- Method for preparing chiral gamma-amino alcohol and chiral alpha-allyl alcohol by one-pot method
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The invention relates to a method for preparing chiral gamma-amino alcohol and chiral alpha-allyl alcohol by a one-pot method. The method comprises the following steps: making a racemic alpha-allyl alcohol compound, an amine compound, a chiral ruthenium complex and an alkaline reagent react in an organic solvent, and carrying out separation and purification after completion of the reaction, so that chiral gamma-aminoalcohols and chiral alpha-allylalcohol are prepared, wherein a chiral ruthenium complex is selected from one of them. According to the preparation method of the chiral compound, two chiral compounds with wide purposes, namely the chiral gamma-amino alcohol and the chiral alpha-allyl alcohol, are obtained at the same time through a one-pot reaction, the reaction is simple, the atom economy is high, few by-products are produced, and the requirements of green chemistry are met.
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Paragraph 0047-0058; 0259-0269
(2020/12/15)
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- A new monooxygenase from: Herbaspirillum huttiense catalyzed highly enantioselective epoxidation of allylbenzenes and allylic alcohols
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Asymmetric epoxidation is a green route to enantiopure epoxides, but often suffers from low enantioselectivity toward unconjugated terminal alkenes. Mining of the NCBI non-redundant protein sequences with a reconstructed ancestral sequence based on six st
- Lin, Hui,Tang, Yanhong,Dong, Shuang,Lang, Ruibo,Chen, Hongge
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p. 2145 - 2151
(2020/04/17)
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- Copper(I) Diphosphine Bifluoride Complexes as Efficient Preactivated Catalysts for Nucleophilic Addition on Unsaturated Functional Groups
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Herein we report the synthesis of a family of copper(I) diphosphine bifluoride complexes, their characterization, and their use as efficient preactivated catalysts for nucleophilic copper addition of pronucleophiles on unsaturations. Their use as mechanistic probes is also highlighted by the identification of two copper deuterides.
- Rasson, Corentin,Riant, Olivier
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supporting information
p. 835 - 840
(2020/02/13)
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- Aromatic farnesyl compound and application thereof
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Aromatic farnesyl compound and application of a pharmaceutical salt thereof as an inhibitor of α-glucosidase, dipeptidyl peptidase-4, aldose reductase, protein tyrosine phosphatase-1B or HMG-CoA reductase, or use thereof in preparing medicine and functional healthcare products having a liver protective function and/or for treating and/or preventing type II diabetes, diabetic retinopathy, diabetic foot disease, and hyperlipidemia.
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Page/Page column 16
(2019/10/29)
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- Enantioselective vinylation of aldehydes with the vinyl Grignard reagent catalyzed by magnesium complex of chiral BINOLs
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Enantioselective vinylation of aldehydes via direct catalytic asymmetric Grignard reaction of aldehdyes and the vinyl Grinard reagent is a long-standing challenge. This work demonstrated that the magnesium (S)-3,3′-dimethyl BINOLate enantioselectively catalyze the direct vinylation of aldehydes with the deactivated vinylmagnesium bromide by bis(2-[N,N′-dimethylamino]ethyl) ether (BDMAEE) in the addition of n-butylmagnesium chloride. The highest ee of 63% was achieved up to date.
- Wang, Pei,Ma, Guo-Rong,Yu, Sheng-Li,Da, Chao-Shan
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supporting information
p. 79 - 86
(2018/12/13)
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- Leoligin-inspired synthetic lignans with selectivity for cell-type and bioactivity relevant for cardiovascular disease
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Recently, a natural compound leoligin, a furan-type lignan, was discovered as an interesting hit compound with an anti-inflammatory pharmacological activity profile. We developed a modular and stereoselective approach for the synthesis of the edelweiss-de
- Linder, Thomas,Liu, Rongxia,Atanasov, Atanas G.,Li, Yuanfang,Geyrhofer, Sophie,Schwaiger, Stefan,Stuppner, Hermann,Schnürch, Michael,Dirsch, Verena M.,Mihovilovic, Marko D.
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p. 5815 - 5820
(2019/06/17)
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- Palladium-Catalyzed Formation of Substituted Tetrahydropyrans: Mechanistic Insights and Structural Revision of Natural Products
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A comprehensive study on the stereochemical outcome of palladium-catalyzed formation of 2,4,6-trisubstituted tetrahydropyrans through cyclization of the corresponding allylic acetates using both Pd(0) and Pd(II) catalysts is presented. We have found that
- Della-Felice, Franco,De Assis, Francisco F.,Sarotti, Ariel M.,Pilli, Ronaldo A.
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p. 1545 - 1560
(2019/03/26)
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- Structural Modification of Natural Product Ganomycin i Leading to Discovery of a α-Glucosidase and HMG-CoA Reductase Dual Inhibitor Improving Obesity and Metabolic Dysfunction in Vivo
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It is a great challenge to develop drugs for treatment of metabolic syndrome. With ganomycin I as a leading compound, 14 meroterpene derivatives were synthesized and screened for their α-glucosidase and HMG-CoA reductase inhibitory activities. As a result, a α-glucosidase and HMG-CoA reductase dual inhibitor ((R,E)-5-(4-(tert-butyl)phenyl)-3-(4,8-dimethylnona-3,7-dien-1-yl)furan-2(5H)-one, 7d) with improved chemical stability and long-term safety was obtained. Compound 7d showed multiple and strong in vivo efficacies in reducing weight gain, lowering HbAlc level, and improving insulin resistance and lipid dysfunction in both ob/ob and diet-induced obesity (DIO) mice models. Compound 7d was also found to reduce hepatic steatosis in ob/ob model. 16S rRNA gene sequencing, SCFA, and intestinal mucosal barrier function analysis indicated that gut microbiota plays a central and causative role in mediating the multiple efficacies of 7d. Our results demonstrate that 7d is a promising drug candidate for metabolic syndrome.
- Wang, Kai,Bao, Li,Zhou, Nan,Zhang, Jinjin,Liao, Mingfang,Zheng, Zhongyong,Wang, Yujing,Liu, Chang,Wang, Jun,Wang, Lifeng,Wang, Wenzhao,Liu, Shuangjiang,Liu, Hongwei
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p. 3609 - 3625
(2018/05/01)
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- Isothiourea-Catalysed Acylative Kinetic Resolution of Aryl–Alkenyl (sp2vs. sp2) Substituted Secondary Alcohols
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The non-enzymatic acylative kinetic resolution of challenging aryl–alkenyl (sp2vs. sp2) substituted secondary alcohols is described, with effective enantiodiscrimination achieved using the isothiourea organocatalyst HyperBTM (1 mol %) and isobutyric anhydride. The kinetic resolution of a wide range of aryl–alkenyl substituted alcohols has been evaluated, with either electron-rich or naphthyl aryl substituents in combination with an unsubstituted vinyl substituent providing the highest selectivity (S=2–1980). The use of this protocol for the gram-scale (2.5 g) kinetic resolution of a model aryl–vinyl (sp2vs. sp2) substituted secondary alcohol is demonstrated, giving access to >1 g of each of the product enantiomers both in 99:1 e.r.
- Musolino, Stefania F.,Ojo, O. Stephen,Westwood, Nicholas J.,Taylor, James E.,Smith, Andrew D.
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supporting information
p. 18916 - 18922
(2016/12/26)
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- Synthesis of enantiopure glycidol derivatives via a one-pot two-step enzymatic cascade
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Styrene monooxygenase (SMO) can catalyze the kinetic resolution of secondary allylic alcohols to provide enantiopure glycidol derivatives. To overcome the low theoretical yield of kinetic resolution, we designed a one-pot two-step enzymatic cascade using prochiral α,β-unsaturated ketones as the substrates. An S-specific ketoreductase ChKRED03 was screened for the efficient bioreduction of the substrates to provide (S)-allylic alcohols, which underwent SMO-catalyzed epoxidation to achieve glycidol derivatives with contiguous stereogenic centers. Excellent enantioselectivity (ee > 99%) and diastereoselectivity (de > 99%) were achieved for the majority of the substrates, and product yields reached up to >99%. This journal is
- Liu, Yu-Chang,Liu, Yan,Wu, Zhong-Liu
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p. 2146 - 2152
(2015/03/05)
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- Titanocene(III) chloride mediated radical-induced opening of monosubstituted epoxy acetates for the synthesis of primary allylic alcohols
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A simple and efficient method for the synthesis of primary allylic alcohols from monosubstituted epoxy acetates has been developed using titanocene(III) chloride mediated epoxide ring opening via acetate elimination.
- Chakraborty,Mandal,Roy
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p. 893 - 901
(2015/08/18)
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- Tungsten-catalyzed asymmetric epoxidation of allylic and homoallylic alcohols with hydrogen peroxide
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A simple, efficient, and environmentally friendly asymmetric epoxidation of primary, secondary, tertiary allylic, and homoallylic alcohols has been accomplished. This process was promoted by a tungsten-bishydroxamic acid complex at room temperature with the use of aqueous 30% H2O2 as oxidant, yielding the products in 84-98% ee.
- Wang, Chuan,Yamamoto, Hisashi
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supporting information
p. 1222 - 1225
(2014/02/14)
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- Concise syntheses and biological activities of ganomycin I and fornicin A
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The first enantioselective syntheses of ganomycin I, a meroterpenoid isolated from the Vietnamese mushroom Ganoderma colossum, and the related meroterpenoid fornicin A were accomplished. Our methodology for the total syntheses of these compounds featured the construction of the butenolide moiety by asymmetric dihydroxylation followed by Julia-Kocienski type olefin formation and ring-closing metathesis reactions. The absolute configurations of the two natural products were determined by comparisons of specific rotation. A cell-based assay of the synthetic compounds with transfected human embryonic kidney 293 tetoff (E-PR293) cells indicated that ganomycin I possesses cytotoxicity and fornicin A possesses weak anti-HIV-1 protease activity without cytotoxicity.
- Yajima, Arata,Urao, Shota,Katsuta, Ryo,Nukada, Tomoo
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p. 731 - 738
(2014/03/21)
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- Concise Syntheses and Biological Activities of Ganomycin i and Fornicin A
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The first enantioselective syntheses of ganomycin I, a meroterpenoid isolated from the Vietnamese mushroom Ganoderma colossum, and the related meroterpenoid fornicin A were accomplished. Our methodology for the total syntheses of these compounds featured the construction of the butenolide moiety by asymmetric dihydroxylation followed by Julia-Kocienski type olefin formation and ring-closing metathesis reactions. The absolute configurations of the two natural products were determined by comparisons of specific rotation. A cell-based assay of the synthetic compounds with transfected human embryonic kidney 293 tet-off (E-PR293) cells indicated that ganomycin I possesses cytotoxicity and fornicin A possesses weak anti-HIV-1 protease activity without cytotoxicity.
- Yajima, Arata,Urao, Shota,Katsuta, Ryo,Nukada, Tomoo
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p. 731 - 738
(2015/10/05)
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- Mechanistic basis for the enantioselectivity of the anaerobic hydroxylation of alkylaromatic compounds by ethylbenzene dehydrogenase
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The enantioselectivity of reactions catalyzed by ethylbenzene dehydrogenase, a molybdenum enzyme that catalyzes the oxygen-independent hydroxylation of many alkylaromatic and alkylheterocyclic compounds to secondary alcohols, was studied by chiral chromatography and theoretical modeling. Chromatographic analyses of 22 substrates revealed that this enzyme exhibits remarkably high reaction enantioselectivity toward (S)-secondary alcohols (18 substrates converted with > 99% ee). Theoretical QM:MM modeling was used to elucidate the structure of the catalytically active form of the enzyme and to study the reaction mechanism and factors determining its high degree of enantioselectivity. This analysis showed that the enzyme imposes strong stereoselectivity on the reaction by discriminating the hydrogen atom abstracted from the substrate. Activation of the pro(S) hydrogen atom was calculated to be 500 times faster than of the pro(R) hydrogen atom. The actual hydroxylation step (i.e., hydroxyl group rebound reaction to a carbocation intermediate) does not appear to be enantioselective enough to explain the experimental data (the calculated rate ratios were in the range of only 2-50 for pro(S): pro(R)-oriented OH rebound).
- Szaleniec, Maciej,Dudzik, Agnieszka,Kozik, Bart?omiej,Borowski, Tomasz,Heider, Johann,Witko, Ma?gorzata
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- Synthesis and reactions of the optically active selenols derived from monoterpenes Dedicated to Professor Jacek Gawronski on the occasion of his 70th birthday
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A convenient methodology for the synthesis of optically active selenols, derived from p-menthane, carane, and pinane, is described. The selenols were oxidized with air to give the optically active diselenides, and were also converted into the corresponding allylic selenides via reaction with Z- and E-cinnamyl, geranyl, and neryl chlorides. Oxidation of the allylic selenides with mCPBA gave the optically active alcohols via [2,3]-sigmatropic rearrangement of the in situ generated allylic selenoxides.
- Scianowski, Jacek,Rafalski, Jaroslaw,Banach, Anna,Czaplewska, Justyna,Komoszynska, Anna
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p. 1089 - 1096
(2013/10/08)
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- A chiral sulfoxide-ligated ruthenium complex for asymmetric catalysis: Enantio- and regioselective allylic substitution
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The design and synthesis of a novel chiral sulfoxide-ligated cyclopentadienyl ruthenium complex is described. Its utility as an asymmetric variant of [CpRu(MeCN)3]PF6 is demonstrated through its ability to function in the branched-selective asymmetric allylic alkylation of phenols and carboxylic acids. Water has also been shown to act as a competent nucleophile in this reaction to generate branched allyl alcohols with good regio- and enantioselectivities.
- Trost, Barry M.,Rao, Meera,Dieskau, Andre P.
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p. 18697 - 18704
(2014/01/06)
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- Kinetic resolution of aryl alkenylcarbinols catalyzed by Fc-PIP
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An effective kinetic resolution of a variety of aryl alkenylcarbinols catalyzed by nonenzymatic acyl transfer catalyst Fc-PIP was developed, affording corresponding unreacted alcohols in good to excellent ee value up to 99% and with selectivity factors up to 24.
- Hu, Bin,Meng, Meng,Jiang, Shanshan,Deng, Weiping
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experimental part
p. 1289 - 1294
(2012/08/28)
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- Enantioselective allylic thioetherification: The effect of phosphoric acid diester on iridium-catalyzed enantioconvergent transformations
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You'll take the high road and I'll take the low road: Enantioenriched allylic thioethers have been synthesized from chiral racemic allylic alcohols. The combination of an Ir-(P,alkene) complex and dibutyl phosphoric acid are required to attain high select
- Roggen, Markus,Carreira, Erick M.
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supporting information; experimental part
p. 8652 - 8655
(2012/10/08)
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- Ruthenium-catalyzed regio- and enantioselective allylic substitution with water: Direct synthesis of chiral allylic alcohols
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Less is more: A new route to access chiral allylic alcohols through the regio- and enantioselective substitution of monosubstituted allylic chlorides with water has been developed. The reaction is catalyzed effectively by planar-chiral cyclopentadienyl ruthenium complexes (see scheme). Copyright
- Kanbayashi, Naoya,Onitsuka, Kiyotaka
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supporting information; experimental part
p. 5197 - 5199
(2011/06/26)
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- Highly efficient kinetic resolution of allylic alcohols with terminal double bond
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In this study, the lipase-catalyzed kinetic resolution (Novozyme 435) was employed to prepare chiral allylic alcohols and acetates with terminal double bonds in enantiomeric excesses ranging from 94 to >99 %.
- Marques, Francisco A.,Oliveira, Marcos A.,Frensch, Gustavo,Sales Maia, Beatriz Helena L. N.,Barison, Andersson,Lenz, Cesar A.,Guerrero Jr., Palimecio G.
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experimental part
p. 696 - 700
(2012/06/04)
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- Enantioselective allylic etherification: Selective coupling of two unactivated alcohols
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An Ir(P,alkene) complex catalyzes the enantioselective allylic etherification of unactivated secondary allylic alcohols. Useful levels of enantioselectivity and yield were achieved with this operationally easy and robust protocol. Initial kinetic studies indicate a significant rate difference for the substrate enantiomers, allowing for a resolution process. cod=1,5-cyclooctadiene Copyright
- Roggen, Markus,Carreira, Erick M.
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scheme or table
p. 5568 - 5571
(2011/08/05)
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- Enantio- and regioselective iridium-catalyzed allylic hydroxylation
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The first enantioselective allylic hydroxylation to prepare branched allylic alcohols directly is described. Bicarbonate was used as nucleophile in conjunction with new single component Ir-catalysts, which are stable to air and water. Excellent regio- and
- Gaertner, Martin,Mader, Steffen,Seehafer, Kai,Helmchen, Guenter
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supporting information; experimental part
p. 2072 - 2075
(2011/04/16)
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- Kinetic resolution of allylic alcohols via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic allylic alcohols has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 968. Substituent effect is briefly discussed.
- Chen, Peiran,Xiang, Peng
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experimental part
p. 5758 - 5760
(2011/12/03)
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- Highly diastereo- and enantio-selective epoxidation of secondary allylic alcohols catalyzed by styrene monooxygenase
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Enantiomerically enriched glycidol derivatives with contiguous stereogenic centers were obtained in a highly diastereo- and enantio-selective epoxidation catalyzed with the styrene monooxygenase StyAB2.
- Lin, Hui,Liu, Yan,Wu, Zhong-Liu
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supporting information; experimental part
p. 2610 - 2612
(2011/04/26)
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- Chiral phosphonite, phosphite and phosphoramidite η6-arene- ruthenium(ii) complexes: Application to the kinetic resolution of allylic alcohols
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The synthesis and characterization of chiral arene-ruthenium complexes [RuCl2(η6-arene){(R)-PR(binaphthoxy)}] (arene = benzene (1), p-cymene (2), mesitylene (3); R = Ph (a), OPh (b), piperidyl (c)) are described. Derivatives 1-3 have been employed to promote the kinetic resolution of allylic alcohols through a redox-isomerization process. As a general trend, the best selectivities are attained with the more sterically hindered catalysts i.e. those containing p-cymene or mesitylene ligands. The Royal Society of Chemistry 2010.
- Fernandez-Zumel, Mariano A.,Lastra-Barreira, Beatriz,Scheele, Marcus,Diez, Josefina,Crochet, Pascale,Gimeno, Jose
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experimental part
p. 7780 - 7785
(2010/10/03)
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- Enzymatic kinetic resolution of primary allenic alcohols. Application to the total synthesis and stereochemical assignment of striatisporolide A
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Crude Porcine pancreatic lipase was successfully used for the kinetic resolution of axially chiral primary allenic alcohols providing very high enantioselectivities with E values above 200. This simple access to optically active allenes was applied to the total synthesis of the fungal metabolite (-)-striatisporolide A, allowing its unambiguous stereochemical assignment.
- Deska, Jan,Baeckvall, Jan-E.
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scheme or table
p. 3379 - 3381
(2010/01/06)
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- Olefin cross-metathesis based approach for the stereoselective total synthesis of (+)-cardiobutanolide
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Olefin cross-metathesis approach to (+)-cardiobutanolide has been achieved starting from d-mannitol utilizing Sharpless kinetic resolution and Sharpless asymmetric dihydroxylation.
- Radha Krishna, Palakodety,Shiva Kumar
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scheme or table
p. 6676 - 6679
(2010/01/18)
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- Lewis acid/CpRu dual catalysis in the enantioselective decarboxylative allylation of ketone enolates
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The addition of a Lewis acidic metal triflate salt Mg(OTf)2 as co-catalyst in the CpRu-catalyzed decarboxylative allylation of in situ-generated ketone enolates allows the reaction to proceed at lower temperature with higher regio- and enantios
- Linder, David,Austeri, Martina,Lacour, Jerome
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supporting information; scheme or table
p. 4057 - 4061
(2009/12/06)
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- Synthesis of enantiopure 1-arylprop-2-en-1-ols and their tert-butyl carbonates
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(Chemical Equation Presented) Enantiomerically pure 1-arylpropenols 8 have been prepared by resolution of the corresponding racemates, using the lipase formulation Novozyme 435. Deprotonation of the latter alcohols with n-BuLi, followed by derivatization with (t- BuO)2CO, afforded the corresponding carbonates 5. Optimization of the process is presented.
- Stambasky, Jan,Malkov, Andrei V.,Kocovsky, Pavel
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supporting information; body text
p. 9148 - 9150
(2009/04/11)
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- Ruthenium-catalyzed synthesis of allylic alcohols: Boronic acid as a hydroxide source
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Secondary allylic alcohols were synthesized from linear allylic halides or carbonates using a catalytic amount of a ruthenium complex in the presence of boronic acid. The effects of solvent, base, ruthenium precursor, and boronic acid were fully explored, and the scope of the reaction was extended to various sub-strates. We also describe a preliminary investigation towards an enantioselective process.
- Bouziane, Asmae,Helou, Marion,Carboni, Bertrand,Carreaux, Francois,Demerseman, Bernard,Bruneau, Christian,Renaud, Jean-Luc
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scheme or table
p. 5630 - 5637
(2009/05/27)
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- Vanadium-catalyzed enantioselective desymmetrization of meso secondary allylic alcohols and homoallylic alcohols
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(Chemical Equation Presented) Desymmetrization isn't complex: The substrate scope for vanadium-catalyzed epoxidation has been extended. In addition to various allylic alcohols, homoallylic alcohols can also be desymmetrized by using vanadium/bishydroxamic
- Li, Zhi,Zhang, Wei,Yamamoto, Hisashi
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scheme or table
p. 7520 - 7522
(2009/03/12)
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- Enantioselective hydrolysis of 1-arylallyl acetates catalyzed by Candida antarctica lipase
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(R)-1-Arylallyl alcohols were obtained with excellent enantioselectivities via kinetic resolution of the corresponding acetates using immobilized Candida antarctica lipase. The scope and limitations of this reaction were investigated. The best results are obtained using the water/acetonitrile solvent system, and the reaction tolerates a variety of aryl and heteroaryl substituents.
- Kadnikova, Ekaterina N.,Thakor, Vikalp A.
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p. 1053 - 1058
(2008/09/19)
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- Development and application of versatile bis-hydroxamic acids for catalytic asymmetric oxidation
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In this article, we describe the development and preliminary results of our new designed C2-symmetric bis-hydroxamic acid (BHA) ligands and the application of the new ligands for vanadium-catalyzed asymmetric epoxidation of allylic alcohols as well as homoallylic alcohols. From this success we demonstrate the versatile nature of BHA in the molybdenum catalyzed asymmetric oxidation of unfunctionalized olefins and sulfides.
- Barlan, Allan U.,Zhang, Wei,Yamamoto, Hisashi
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p. 6075 - 6087
(2008/02/03)
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- A highly enantioselective synthesis of chiral allylic alcohols by asymmetric addition of novel mixed reagents of trialkenylbismuthines/dialkylzincs to aldehydes
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A novel mixture of reagents of trialkenylbismuthines/dialkylzincs was developed and applied toward the synthesis of chiral allylic alcohols. The chiral β-amino alcohols catalyzed addition of the mixed reagents of trialkenylbismuthines/dialkylzincs to alde
- Sato, Itaru,Asakura, Noriaki,Iwashita, Taizo
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p. 2638 - 2642
(2008/04/05)
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- Iridium(I)-catalyzed stereospecific decarboxylative allylic amidation of chiral branched benzyl allyl imidodicarboxylates
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(Chemical Equation Presented) Ir(I)-catalyzed decarboxylase allylic amidation of chiral branched benzyl allyl imidodicarboxylates has been shown to proceed with complete retention of enantiomeric purity and configuration. The transformation is stereospecific and appears to be quite general, accommodating a wide range of R groups.
- Singh, Om V.,Han, Hyunsoo
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p. 4801 - 4804
(2008/03/15)
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- Iridium-catalyzed enantioselective synthesis of allylic alcohols: Silanolates as hydroxide equivalents
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(Chemical Equation Presented) Masked hydroxide: A highly regio- and enantioselective Ir-catalyzed allylic etherification of acyclic, achiral allylic carbonates can be achieved by using potassium silanolates as nucleophiles. The use of these hydroxide equi
- Lyothier, Isabelle,Defieber, Christian,Carreira, Erick M.
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p. 6204 - 6207
(2007/10/03)
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- Process for producing an alcohol or a silyl ether thereof
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A process for producing an alcohol or a silyl ether thereof of formula (4): wherein R1 represents a hydrocarbon, a heterocyclic, or an alkoxycarbonyl group; R2 represents hydrogen or CO2R; X represents an aryl or an alkenyl group of formula (3): and R8 represents hydrogen or a silyl residue, by reacting a compound R1(C═O)R2 with a silane (R3)2R4Si—X, wherein R3 and R4 each represents an alkyl, an alkoxy, or an aryl group; in the presence of (i) a catalyst component containing copper fluoride or a catalyst component containing a copper compound and a fluoride and (ii) a bidentate phosphine compound or in the presence of a complex obtained from the foregoing components.
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Page/Page column 9
(2008/06/13)
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- Enantioselective epoxidation of allylic alcohols by a chiral complex of vanadium: An effective controller system and a rational mechanistic model
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(Chemical Equation Presented) Bishydroxamic acid derivatives are used as ligands for a vanadium catalyst in the preparation of epoxy alcohols (see scheme). The methodology uses aqueous tert-butyl hydroperoxide (TBHP) as an achiral oxidant, low catalyst loading, low reaction temperatures (0°C to room temperature), and simple workup procedures. The reaction is applied to the kinetic resolution of a secondary allylic alcohol and the preparation of small epoxy alcohols. R1, R2, R3: alkyl, aryl, H.
- Zhang, Wei,Basak, Arindrajit,Kosugi, Yuji,Hoshino, Yujiro,Yamamoto, Hisashi
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p. 4389 - 4391
(2007/10/03)
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- Enantioselective alkenylation and phenylation catalyzed by a chiral CuF complex
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A new method for CuF-catalyzed alkenylation and phenylation of aldehydes and an activated ketone using air- and moisture-stable alkenylsilanes and phenylsilane as a nucleophile is described. This methodology was extended to highly enantioselective catalytic alkenylation and phenylation using DTBM-SEGPHOS as a chiral ligand. Substrate generality is broad, and an alkenylsilane with a long alkyl chain and an internal alkenylsilane can be also used as a nucleophile. The key to success partly involves the accelerated regeneration of reactive alkenylcopper and phenylcopper through transmetalation from the silylated nucleophiles, and stabilization of the reactive copper reagents, both of which are effected by the diphosphine ligands. Copyright
- Tomita, Daisuke,Wada, Reiko,Kanai, Motomu,Shibasaki, Masakatsu
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p. 4138 - 4139
(2007/10/03)
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- Aminocyclopentadienyl Ruthenium Complexes as Racemization Catalysts for Dynamic Kinetic Resolution of Secondary Alcohols at Ambient Temperature
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Aminocyclopentadienyl ruthenium complexes, which can be used as room-temperature racemization catalysts with lipases in the dynamic kinetic resolution (DKR) of secondary alcohols, were synthesized from cyclopenta-2,4-dienimines, Ru3(CO)12, and CHCl 3: [2,3,4,5-Ph4(η5-C 4CNHR)]Ru-(CO)2Cl (4: R = i-Pr; 5: R = n-Pr; 6: R = t-Bu), [2,5-Me2-3,4-Ph2(η5-C 4CNHR)]Ru(CO)2Cl (7: R = i-Pr; 8: R = Ph), and [2,3,4,5-Ph4(η5-C4CNHAr)]Ru(CO) 2Cl (9: Ar =p-NO2C6H4; 10: Ar = p-ClC6H4; 11: Ar = Ph; 12: Ar = p-OMeC6H 4; 13: Ar = p-NMe2C6H4). The tests in the racemization of (S)-4-phenyl-2-butanol showed that 7 is the most active catalyst, although the difference decreased in the DKR. Complex 4 was used in the DKR of various alcohols; at room temperature, not only simple alcohols but also functionalized ones such as allylic alcohols, alkynyl alcohols, diols, hydroxyl esters, and chlorohydrins were successfully transformed to chiral acetates. In mechanistic studies for the catalytic racemization, ruthenium hydride 14 appeared to be a key species. It was the major organometallic species in the racemization of (S)-1-phenylethanol with 4 and potassium tert-butoxide. In a separate experiment, (S)-1-phenylethanol was racemized catalytically by 14 in the presence of acetophenone.
- Choi, Jun Ho,Choi, Yoon Kyung,Kim, Yu Hwan,Park, Eun Sil,Kim, Eun Jung,Kim, Mahn-Joo,Park, Jaiwook
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p. 1972 - 1977
(2007/10/03)
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