- Synthesis of a new asymmetric cyclopentadienyl ligand: application to the preparation of a trivalent samarium complex
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A short synthesis of a new asymmetric cyclopentadienyl ligand 2 (Cp'H) substituted by a benzyl ether group in the β position on the side chain of the ring is described.Reaction of its potassium salt with samarium triiodide leads to the isolation of a triv
- Weghe, P. Van de,Bied, C.,Collin, J.,Marcalo, J.,Santos, I.
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Read Online
- Acyclic Stereocontrol in the Additions of Nucleophilic Alkenes to α-Chiral N-Sulfonyl Imines
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Diastereoselective Lewis acid-mediated additions of nucleophilic alkenes to N-sulfonyl imines are reported. The canonical polar Felkin–Anh model describing additions to carbonyls does not adequately describe analogous additions to N-sulfonyl imines. Herei
- Moore, Lucas C.,Lo, Anna,Fell, Jason S.,Duong, Matthew R.,Moreno, Jose A.,Rich, Barry E.,Bravo, Martin,Fettinger, James C.,Souza, Lucas W.,Olmstead, Marilyn M.,Houk, Kendall N.,Shaw, Jared T.
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Read Online
- Preparation of Optically Active (S)-2-(Benzyloxy)propanal
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A convenient and large scale amenable preparation of optically active ethyl (S)-2-(benzyloxy)propionate (5) from ethyl (S)-lactate (4), and the conversion of the ester (5) by two alternative methods into (S)-2-(benzyloxy)propanal (1) are described.
- Varelis, Peter,Johnson, Brian L.
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Read Online
- 6-HETEROARYLOXY BENZIMIDAZOLES AND AZABENZIMIDAZOLES AS JAK2 INHIBITORS
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The present disclosure provides 6-heteroaryloxy benzimidazole and azabenzimidazole compounds and compositions thereof useful for inhibiting JAK2.
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- Benzoxaborole Catalyst for Site-Selective Modification of Polyols
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The site-selective modification of polyols bearing several hydroxyl groups without the use of protecting groups remains a significant challenge in synthetic chemistry. To address this problem, novel benzoxaborole derivatives were designed as efficient catalysts for the highly site-selective and protecting-group-free modification of polyols. To identify the effective substituent groups enhancing the catalytic activity and selectivity, a series of benzoxaborole catalysts 1a–k were synthesized. In-depth analysis for the substituent effect revealed that 1i–k, bearing multiple electron-withdrawing fluoro- and trifluoromethyl groups, exhibited the greatest catalytic activity and selectivity. Moreover, 1i-catalyzed benzoylation, tosylation, benzylation, and glycosylation of various cis-1,2-diol derivatives proceeded with good yield and site-selective manner.
- Kusano, Shuhei,Miyamoto, Shoto,Matsuoka, Aki,Yamada, Yuji,Ishikawa, Ryuta,Hayashida, Osamu
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supporting information
p. 1598 - 1602
(2020/02/11)
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- Regio/site-selective alkylation of substrates containing a: Cis -, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system
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In this study, we reported the regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with FeCl3 as a key catalyst. A catalytic system consisting of FeCl3 (0.01-0.1 equiv.) and dipivaloylmethane (FeCl3/dipivaloylmethane = 1/2) was used to catalyze the alkylation in the presence of a base. The produced selectivities and isolated yields were similar to those obtained by methods using the same amount of FeL3 (L = acylacetone ligand) as the catalyst in most cases. The previously reported FeL3 catalysts for alkylation are not commercially available and have to be synthesized prior to use. In contrast, FeCl3 and dipivaloylmethane (Hdipm) are very common and inexpensive nontoxic reagents in the lab, thereby making the method much greener and easier to handle. Mechanism studies confirmed for the first time that FeCl3 initially reacts with two equivalents of Hdipm to form [Fe(dipm)3] in the presence of a base in acetonitrile, followed by the formation of a five or six-membered ring intermediate between [Fe(dipm)3] and two hydroxyl groups of the substrate. A subsequent reaction between the cyclic intermediate and the alkylating agent results in selective alkylation of the substrate.
- Lv, Jian,Liu, Yu,Zhu, Jia-Jia,Zou, Dapeng,Dong, Hai
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supporting information
p. 1139 - 1144
(2020/03/11)
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- COMPOUNDS FOR USE IN THE TREATMENT OR PROPHYLAXIS OF PAIN, INFLAMMATION AND/OR AUTOIMMUNITY
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The present invention relates to a polymorphic form of (S,S)-2-N(3-O-(propan-2-ol)-1-propyl- 4-hydroxybenzene)-3-phenylpropylamide or synonymously named N-[2-(4-Hydroxy-phenyl)- -(2-hydroxy-propoxymethyl)-ethyl]-3-phenyl-propionamide and to the treatment
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Page/Page column 15-16
(2020/08/13)
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- Non-naturally Occurring Regio Isomer of Lysophosphatidylserine Exhibits Potent Agonistic Activity toward G Protein-Coupled Receptors
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Lysophosphatidylserine (LysoPS), an endogenous ligand of G protein-coupled receptors, consists of l-serine, glycerol, and fatty acid moieties connected by phosphodiester and ester linkages, respectively. An ester linkage of phosphatidylserine can be hydrolyzed at the 1-position or at the 2-position to give 2-acyl lysophospholipid or 1-acyl lysophospholipid, respectively. 2-Acyl lysophospholipid is in nonenzymatic equilibrium with 1-acyl lysophospholipid in vivo. On the other hand, 3-acyl lysophospholipid is not found, at least in mammals, raising the question of whether the reason for this might be that the 3-acyl isomer lacks the biological activities of the other isomers. Here, to test this idea, we designed and synthesized a series of new 3-acyl lysophospholipids. Structure-activity relationship studies of more than 100 "glycol surrogate"derivatives led to the identification of potent and selective agonists for LysoPS receptors GPR34 and P2Y10. Thus, the non-natural 3-acyl compounds are indeed active and appear to be biologically orthogonal with respect to the physiologically relevant 1-and 2-acyl lysophospholipids.
- Nakamura, Sho,Sayama, Misa,Uwamizu, Akiharu,Jung, Sejin,Ikubo, Masaya,Otani, Yuko,Kano, Kuniyuki,Omi, Jumpei,Inoue, Asuka,Aoki, Junken,Ohwada, Tomohiko
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p. 9990 - 10029
(2020/10/18)
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- A Br?nsted Acid Catalyzed Cascade Reaction for the Conversion of Indoles to α-(3-Indolyl) Ketones by Using 2-Benzyloxy Aldehydes
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A Br?nsted acid catalyzed, operationally simple, scalable route to several functionalized α-(3-indolyl) ketones has been developed and the long-standing regioisomeric issue has been eliminated by choosing appropriate carbonyls. A readily available and cheap bottle reagent was used as the catalyst. This protocol was also applicable to the synthesis of densely functionalized α-(3-pyrrolyl) ketones. A detailed mechanistic study confirmed the involvement of enolether as a reaction intermediate. Several postsynthetic modifications along with easy access to β-carboline, tryptamines, tryptophols, and spiro-indolenine proclaim the synthetic utility of this powerful building block. On the basis of this concept, functionalized carbazoles were constructed by a cascade annulation strategy.
- Banerjee, Ankush,Maji, Modhu Sudan
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supporting information
p. 11521 - 11527
(2019/08/16)
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- C -Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts
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A versatile, selective, and recyclable heterogeneous catalytic method for the methylation of C-H bonds in alcohols, ketones, and indoles with methanol under oxidant-free conditions using a Pt-loaded carbon (Pt/C) catalyst in the presence of NaOH is reported. This catalytic system is effective for various methylation reactions: (1) the β-methylation of primary alcohols, including aryl, aliphatic, and heterocyclic alcohols, (2) the α-methylation of ketones, and (3) the selective C3-methylation of indoles. The reactions are driven by a borrowing-hydrogen mechanism. The reaction begins with the dehydrogenation of the alcohol(s) to afford aldehydes, which subsequently undergo a condensation reaction with the nucleophile (aldehyde, ketone, or indole), followed by hydrogenation of the condensation product by Pt-H species to yield the desired product. In all of the methylation reactions explored in this study, the Pt/C catalyst exhibits a significantly higher turnover number than other previously reported homogeneous catalytic systems. Moreover, it is demonstrated that the high catalytic activity of Pt can be rationalized in terms of the adsorption energy of hydrogen on the metal surface, as revealed by density functional theory calculations on different metal surfaces.
- Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Jamil, Md. A. R.,Toyao, Takashi,Shimizu, Ken-Ichi
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p. 3091 - 3103
(2018/04/14)
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- BENZAMIDE COMPOUNDS AS ROR GAMMA MODULATORS
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The present disclosure is directed to compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein ring A, R1, R2, R3, R4, R5, n and p are as defined herein, which are active as modulators of retinoid-related orphan receptor gamma t (RORγt). These compounds prevent, inhibit, or suppress the action of RORγt and are therefore useful in the treatment of RORγt mediated diseases, disorders, syndromes or conditions such as, e.g., pain, inflammation, COPD, asthma, rheumatoid arthritis, colitis, multiple sclerosis, psoriasis, neurodegenerative diseases and cancer.
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Page/Page column 41
(2017/12/16)
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- Epoxide hydrolysis and alcoholysis reactions over crystalline Mo-V-O oxide
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Crystalline Mo-V-O oxides have been used as a catalyst for the hydrolysis and alcoholysis of propylene oxide to diols and ethers, respectively. Relationships between the active crystal facet, the acidity of Mo-V-O catalysts and the activity have been established. Our results indicate that the a-b plane is the active facet for the hydrolysis reaction.
- Zhang, Xiaochen,Wang, Min,Zhang, Chaofeng,Lu, Jianmin,Wang, Yehong,Wang, Feng
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p. 70842 - 70847
(2016/08/05)
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- Imidazolium-based chiral ionic liquids: Synthesis and application
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Synthesis of chiral ionic liquids containing an imidazole nucleus and chiral centers on N-substituents is reported. [(2S,3S)-2,3-Dihydroxybutane-1,4- bis(3-butylimidazolium)]-[bis(trifluoromethanesulfonyl)amide]2 and [(4S,5S)-2-phenyl-1,3-dioxo
- Suzuki, Yumiko,Wakatsuki, Junichiro,Tsubaki, Mariko,Sato, Masayuki
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p. 9690 - 9700
(2013/10/22)
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- ISOLATED STEREOISOMERIC FORMS OF (S) 2-N (3-O-(PROPAN 2-OL) -1-PROPYL-4-HYDROXYBENZENE) -3-PHENYLPROPYLAMIDE
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The present invention relates to isolated stereoisomeric forms of the compound (S)2-N(3- 0-(propan 2-ol)-l-propyl-4-hydroxybenzene)-3-phenylpropylamide. Specifically, the present invention relates to the use of (S)2-N(3-0-((S)propan 2-ol)-l-propyl-4- hydr
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Page/Page column 15
(2013/06/27)
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- Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: Expansion of substrate scope and mechanistic studies
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Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
- Lee, Doris,Williamson, Caitlin L.,Chan, Lina,Taylor, Mark S.
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supporting information; experimental part
p. 8260 - 8267
(2012/07/14)
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- Copper(I)-catalyzed asymmetric desymmetrization: Synthesis of five-membered-ring compounds containing all-carbon quaternary stereocenters
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A highly stereoselective catalytic alkylation sequence for the synthesis of highly functionalized and versatile five-membered-ring compounds bearing all-carbon quaternary stereocenters was developed. Enantioselective desymmetrization of achiral cyclopentene-1,3-diones was thus executed by chiral Cu-phosphoramidite catalysts. A variety of complicated cyclopentane derivatives can be synthesized with excellent stereoselectivities using a low catalyst loading in a one-pot operation.
- Aikawa, Kohsuke,Okamoto, Tatsuya,Mikami, Koichi
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supporting information; experimental part
p. 10329 - 10332
(2012/07/30)
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- NOVEL RUTHENIUM CARBONYL COMPLEX HAVING TRIDENTATE LIGAND, ITS PRODUCTION METHOD AND USE
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The present invention relates to a ruthenium carbonyl complex that is represented by the following Formula (1): [in-line-formulae]RuXY(CO)(L)??(1)[/in-line-formulae](in the Formula (1), X and Y, which may be the same or different from each other, represent an anionic ligand and L represents a tridentate aminodiphosphine ligand which has two phosphino groups and a —NH— group), its production method, and a method for production of alcohols by hydrogenation-reduction of ketones, esters, and lactones using the complex as a catalyst. The ruthenium carbonyl complex of the invention has a high catalytic activity and it can be easily prepared and handled.
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Page/Page column 11
(2011/10/12)
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- Alkylation and aldol reactions of acyl derivatives of N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine: asymmetric synthesis of α-alkoxy-, α-substituted-β-alkoxy- and α,β-dialkoxyaldehydes
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Treatment of a range of O-protected glycolate derivatives of the chiral auxiliary N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine with KHMDS in the presence of 18-crown-6 followed by addition of an alkyl halide generates α-substituted derivatives with very high levels of diastereoselectivity. Alternatively, reaction of the potassium enolate of a propanoate or O-protected glycolate derivative of N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine with a range of aldehydes gives syn-aldol products with high levels of diastereoselectivity. These adducts may be reductively cleaved with LiAlH4 to give enantiopure α-alkoxy-, α-substituted-β-alkoxy- and α,β-dialkoxyaldehydes in good yield.
- Chernega, Alexander N.,Davies, Stephen G.,Fletcher, Ai M.,Goodwin, Christopher J.,Hepworth, David,Prasad, R. Shyam,Roberts, Paul M.,Savory, Edward D.,Smith, Andrew D.,Thomson, James E.
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experimental part
p. 4167 - 4194
(2010/07/06)
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- A homogeneous catalyst for reduction of optically active esters to the corresponding chiral alcohols without loss of optical purities
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A ruthenium complex was found to catalyze the hydrogen reduction of esters under mild and neutral conditions. A variety of optically active esters can be reduced to the corresponding alcohols in excellent yield without loss of their optical purity or causing undesirable side reactions. Hydrogen reduction needs such simple operations - reaction, concentration, and purification - that the violent quench step and extraction step, which accompany conventional sodium borohydride or lithium aluminum hydride reduction, can be omitted.
- Kuriyama, Wataru,Ino, Yasunori,Ogata, Osamu,Sayo, Noboru,Saito, Takao
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supporting information; experimental part
p. 92 - 96
(2010/06/17)
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- Chiral tetraphenylethenes as novel dopants for calamitic and discotic liquid crystals
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Three series of novel chiral tetraphenylethenes have been prepared: citronellyl-derived ethers 1a, b, lactate-derived ethers 2d, g, h, i and lactate-derived esters 3a-c, e-h. Helical twisting powers (HTPs) were determined for those derivatives of 1-3, whi
- Schreivogel, Alina,Dawin, Ute,Baro, Angelika,Giesselmannb, Frank,Laschat, Sabine
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scheme or table
p. 484 - 494
(2010/04/05)
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- Total synthesis of GEX1A
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(Chemical Equation Presented) An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 (1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.
- Murray, Timothy J.,Forsyth, Craig J.
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supporting information; experimental part
p. 3429 - 3431
(2009/05/11)
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- FUSED HETEROCYCLIC COMPOUND
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A compound of the formula: wherein ring'' A is a 7-membered or 8-membered nitrogen- containing ring optionally further substituted, ring B is an optionally substituted aryl group or an optionally substituted heteroaryl group, X1 is a group represented by -NR3-Y1-, -0-, -S-, -SO-, -SO2- or -CHR3- wherein R3 is a hydrogen atom or'' an optionally substituted aliphatic hydrocarbon group, or R3 may be bonded to the carbon atom of ring B to form an optionally substituted ring structure, and Y1 is a bond or an optionally substituted C1-4 alkylene, R1 is a hydrogen atom, or an optionally substituted group bonded via a carbon atom or a sulfur atom, the formula = shows a single bond or a double bond, when ===R2 is - R2, R2 is a hydrogen atom, or an optionally substituted group bonded via a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and when ===R2 is =R2, R2 is an oxo group, an optionally substituted alkylidene group, or an optionally, substituted imino group.
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Page/Page column 314-315
(2010/11/28)
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- Prototype of a photoswitchable foldamer
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(Figure Presented) Know where to fold 'em: A foldamer exhibiting a light-induced helix-coil transition (see scheme) can be constructed by introducing a photochromic azobenzene moiety (red) into the center of an amphiphilic phenylene ethynylene backbone (blue). This system gives insight into folding and unfolding mechanisms and promises applications in photoresponsive (bio)materials and "smart" delivery devices based on photoresponsive dynamic receptors.
- Khan, Anzar,Kaiser, Christian,Hecht, Stefan
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p. 1878 - 1881
(2007/10/03)
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- Solvolysis of benzyl alcohols and ethers in 1,2-diols and application to a deprotection of benzyl ether-type protecting groups
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Some kinds of benzyl alcohols and ethers react with 1,2-diols, such as ethylene glycol and propylene glycol, at 130-190°C to give 2-hydroxyethyl or 2-hydroxypropyl ethers. Application of this reaction to a deprotection of benzyl ether-type protecting groups, under neutral conditions, was also described. Copyright
- Miyake, Hideyoshi,Fujimura, Masahiro,Tsumura, Takatsugu,Sasaki, Mitsuru
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p. 778 - 779
(2007/10/03)
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- Highly enantioselective lipase-catalyzed kinetic resolution of 2-silyloxy-1-propanol
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The lipase-catalyzed kinetic resolutions of 2-benzyloxy- and 2-silyloxy-1-propanols have been investigated. Efficient modification of the substrate structure with the dimethylphenylsilyl protecting group and the use of lipase PS-D immobilized on diatomace
- Kawanami, Yasuhiro,Itoh, Kennji
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p. 682 - 683
(2007/10/03)
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- Synthesis of new chiral ionic liquids from natural acids and their applications in enantioselective Michael addition
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Two kinds of novel chiral ionic liquids based on imidazolium have been synthesized from chiral pool by a simple and straightforward procedure in good overall yields (44-60%). The application of CILs as reaction media in the enantioselective Michael additi
- Wang, Zhiming,Wang, Qiang,Zhang, Yu,Bao, Weiliang
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p. 4657 - 4660
(2007/10/03)
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- Six-membered chiral phosphine ligands
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A novel class of chiral phosphine ligands useful for producing catalyst for asymmetric reactions with general structure of Formula 1:
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Page/Page column 20
(2008/06/13)
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- The use of nonactivated iminodienophiles in the stereoselective aza-Diels-Alder reaction
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This paper describes the preparation of nitrogen-containing bicycles by the aza-Diels-Alder reaction of nonactivated iminodienophiles and cyclopentadiene. Readily available starting materials such as (S)-(-)-lactate and L-amino acids were used for the pre
- Trifonova, Anna,Andersson, Pher G.
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p. 445 - 452
(2007/10/03)
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- Electron-transfer reduction of selected alcohols with alkalide K-, K+(15-crown-5)2 via organometallic intermediates
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The course of the reaction of alkalide K-, K+ (15-crown-5)2 1 with selected alcohols depends on the kind of alcohol and the mode of substrate delivery. In the case of methanol, potassium methoxide formed initially undergoes destructfion at the excess of 1. It results in potassium oxide and methylpotassium. The latter opens the crown ether ring giving potassium tetraethylene glycoxide vinyl ether and methane. A similar course of the process is observed for propanol. Potassium glycidoxide is the main product formed in the reaction of 1 with glycidol. Its oxirane ring is opened at the excess of 1. Organopotassium alkoxides, i.e., potassium potassiomethoxide and dipotassium potassiopropane-1,2-dioxide are intermediate products of this reaction. They react then with the crown ether. Potassium methoxide, potassium enolate of acetaldehyde, dipotassium propane-1, 2-dioxide and potassium tetraethylene glycoxide vinyl ether are the final products of this process.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert,Krompiec, Stanis,Kasperczyk, Janusz,Rzepa, Józef,Frey, Holger
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p. 2361 - 2367
(2007/10/03)
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- 2-Alkynyl-and 2-alkenyl-pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]-pyrimidine adenosine A2a receptor antagonists
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Compounds having the structural formula I or a pharmaceutically acceptable salt thereof, wherein R is R1, R2, R3, R4 and R5 are H, alkyl or alkoxyalkyl; R6 is H, alkyl, hydroxyalkyl or —CH2F; R7, R8 and R9 are H, alkyl, alkoxy, alkylthio, alkoxyalkyl, halo or —CF3; and Z is optionally substituted aryl, heteroaryl or heteroaryl-alkyl are disclosed. Also disclosed is the use of compounds of formula I in the treatment of central nervous system diseases, in particular Parkinson's disease, alone or in combination with other agents for treating Parkinson's disease, and pharmaceutical compositions comprising them.
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- Diastereoselective rhodium(II)-catalyzed sulfonium ylide formation-[2,3]-sigmatropic rearrangement reaction of chiral non-racemic allylic sulfides
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The tandem sulfonium ylide formation-[2,3]-sigmatropic rearrangement reaction of chiral non-racemic secondary allylic sulfides, (E)-9 and (Z)-10, is found to proceed with high diastereocontrol. The C-5 stereocenter bearing the sulfide group is essential for high diastereoselectivity in the reaction. Transition state conformers are proposed to explain the high diastereoselectivity in the formation of the diastereomeric products, 18a and 18b. The method is applied to the synthesis of (R)-4-(4-chlorophenyl)-2-butyrolactone. Modest enantioselectivity (63% ee) was achieved and this is attributed to partial racemization during the formation of the secondary allylic sulfide 22.
- Wee, Andrew G. H.,Shi, Qing,Wang, Zhongyi,Hatton, Kimberly
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p. 897 - 909
(2007/10/03)
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- Chelation-controlled ester-derived titanium enolate aldol reaction: Diastereoselective syn-aldols with mono- and bidentate aldehydes
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A chelation-controlled and highly diastereoselective synthesis of syn-aldols is described. Aldol reaction of (S)-valinol-derived ester with a variety of aldehydes proceeded with high syn-diastereoselectivities (up to 99:1) and isolated yields (94%).
- Ghosh, Arun K,Kim, Jae-Hun
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p. 5621 - 5624
(2007/10/03)
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- One-Pot Generation and Conversion of Trichloroacetimidates for the Racemization-Free Allylation and Benzylation of α-Hydroxyesters and the Enantiopure Synthesis of a Chiral Diglycole
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Ο-Allylations and Ο-benzylations of α-hydroxy esters (3a-3c) are performed without racemization. The reagents applied, Ο-allyl- and Ο-benzyltrichloroacetimidate (5a, 5b) are prepared and converted in a one-pot-procedure. After protection by benzylation (S)-(-)-ethyl lactate (3a) is converted by a sequence of carbonyl reduction, alcohol activation, ether formation, and deprotection to the optically active diglycole derivative 1a.
- Christoffers, Jens,R??ler, Ulrich
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p. 654 - 658
(2007/10/03)
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- Almond oxynitrilase-catalyzed transformation of aldehydes is strongly influenced by naphthyl and alkoxy substituents
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Different α- and β-substituted aldehydes have been submitted to the catalytic action of almond oxynitrilase (PaHNL), in order to explore the influence of a stereocenter already present in the substrate on the selectivity of this enzyme. The results indicate that naphthyl and alkoxy substituents in the α- and also in the β-position to the aldehyde group significantly influence the stereochemical outcome of the PaHNL-catalyzed transformation.
- Roda, Gabriella,Riva, Sergio,Danieli, Bruno
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p. 3939 - 3949
(2007/10/03)
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- Enantioselective synthesis of β-substituted butyric acid derivatives via orthoester Claisen rearrangement of enzymatically resolved allylic alcohols: Application to the synthesis of (R)-(-)-baclofen
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A three step synthesis of (R)-(-)-baclofen is described. The key step is the orthoester Claisen rearrangement of enantiopure allylic alcohol (S,E)-(-)-1a, affording γ,δ-unsaturated ester (S,E)-(+)-6 with high stereoselectivity. This latter derivative is converted into (R)-(-)-baclofen through a high yield one-pot reaction.
- Brenna, Elisabetta,Caraccia, Nicola,Fuganti, Claudio,Fuganti, Daniela,Grasselli, Piero
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p. 3801 - 3805
(2007/10/03)
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- Highly selective Silver(I) oxide mediated monoprotection of symmetrical diols
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Treatment of symmetrical diol with Ag2O and alkyl halide gave the monoprotected derivative in good to excellent yield.
- Bouzide, Abderrahim,Sauve, Gilles
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p. 5945 - 5948
(2007/10/03)
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- Diastereo- and enantioselective synthesis of 1,2-amino alcohols and protected α-hydroxy aldehydes from glycol aldehyde hydrazones
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Starting from chiral glycol aldehyde hydrazones (S)-2, we prepared differently protected α-hydroxy aldehydes (R)- or (S)-4 as well as N-acetyl-protected 1,2-amino alcohols (R)-11 in high enantiomeric excesses via azaenolate α-alkylation or nucleophilic 1,2-addition to the CN double bond. The successive introduction of two vicinal stereogenic centres opens a new, flexible syn-diastereo- and enantioselective route to functionalised, N-acetyl-protected, vicinal amino alcohols (R,R)-13, which was demonstrated in the case of the γ-amino-β-hydroxycarboxylic acid statin (R,R)-15 and its analogues B. VCH Verlagsgesellschaft mbH, 1996.
- Enders, Dieter,Reinhold, Ulrich
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- Aminodiol HIV protease inhibitors. Synthesis and structure - Activity relationships of P1/P1′ compounds: Correlation between lipophilicity and cytotoxicity
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A series of novel aminodiol inhibitors of HIV protease based on the lead compound 1 with structural modifications at P1′ were synthesized in order to reduce the cytotoxicity of 1. We have observed a high degree of correlation between the lipophilicity and the cytotoxicity of this series of inhibitors. It was found that appropriate substitution at the para position of the P1′ phenyl group of 1 resulted in the identification of equipotent (both against the enzyme and in cell culture) compounds (101, 10m, 10n, and 15c) which possess significantly decreased cytotoxicity.
- Chen, Ping,Cheng, Peter T. W.,Alam, Masud,Beyer, Barbara D.,Bisacchi, Gregory S.,Dejneka, Tamara,Evans, Adelaide J.,Greytok, Jill A.,Hermsmeier, Mark A.,Humphreys, W. Griffith,Jacobs, Glenn A.,Kocy, Octavian,Lin, Pin-Fang,Lis, Karen A.,Marella, Michael A.,Ryono, Denis E.,Sheaffer, Amy K.,Spergel, Steven H.,Sun, Chong-Qing,Tino, Joseph A.,Vite, Gregory,Colonno, Richard J.,Zahler, Robert,Barrish, Joel C.
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p. 1991 - 2007
(2007/10/03)
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- Stereoselective Radical Additions of γ-Oxy-α,β-unsaturated Ester Derivatives; 1,2-Asymmetric Induction in Acyclic and Cyclisation Systems
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Examination was made of 1,2-asymmetric induction in the addition of alkyl radicals to γ-oxy-α,β-unsaturated ester derivatives 1 and 2 prepared from ethyl lactate and (R)-2,3-O-isopropylideneglyceraldehyde 3, respectively.The addition reactions of hexyl, cyclohexyl and 3-phenylpropyl radicals to (Z)-2 derived from aldehyde 3 gave β-addition products with syn-stereoselectivity (syn:anti = 8.6:1 - syn only).The reactions of (E)-2 were non-stereoselective.Based on allylic strain, a transition-state model for the syn-stereoselectivity is proposed. 1,2-Asymmetric induction was carried out in radical cyclisation to synthesize optically active cyclohexane derivatives.
- Morikawa, Tsutomu,Washio, Yoshiaki,Harada, Susumu,Hanai, Ryo,Kayashita, Takashi,et al.
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p. 271 - 282
(2007/10/02)
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- Effective 1,5-asymmetric induction in tin(IV) chloride promoted reactions between aldehydes and (4-alkoxy-2-alkenyl)tributylstannanes
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Transmetallation of (S)-4-benzyloxy-2-pentenyl(tributyl)stannane (1) using tin(IV) chloride generates an allyltin trichloride which reacts in situ with aldehydes to give 1-substituted syn-(3Z)-5-benzyloxyhexenols with excellent stereoselectivity. With chiral aldehydes, the stereoselectivity of the reaction is dominated by the reagent, except for 2-alkoxyaldehydes which show matching and mismatching consistent with preferred Felkin-Anh diastereofacial selectivity.
- McNeill,Thomas
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p. 322 - 334
(2007/10/02)
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- Diastereoselectivity of the thio-Claisen rearrangement of acyclic precursors bearing a chiral centre adjacent to carbon 6
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A number of chiral allylic alcohols have been prepared and submitted to a Mitsunobu reaction with dithioacetic acid. Allyl dithioesters were deprotonated by LDA at -30°C and resulting enethiolates were quenched with iodomethane to afford quantitatively S-
- Desert, Stephane,Metzner, Patrick
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p. 10327 - 10338
(2007/10/02)
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- REDUCTION OF ACETALS WITH CpTiCl3-LiAlH4
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The reduction of cyclic acetals and ketals derived from aromatic or aliphatic aldehydes and ketones with CpTiCl3-LiAlH4 system in diethyl ether at 30 deg C affords the corresponding hydroxyethyl ethers and the corresponding alkyl benzene or aliphatic hydrocarbons.
- Shaozu, Wu,Yin, Chen,Yulan, Zhang
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p. 421 - 424
(2007/10/02)
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- A efficient method for the reductive cleavage of aromatic acetals with ZrCl4-LiAlH4
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In our survey of the chemistry of ZrCl4-LiAlH4, we have found that acetals can be reduced to the corresponding ethers.We have explored the reductive condition and studied the reductive cleavage of different-membered cyclic acetals
- Shaozu, Wu,Yulan, Zhang,Tianhui, Ren
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p. 445 - 447
(2007/10/02)
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- 1,5-Asymmetric induction in reactions between δ-alkoxyallylstannanes and aldehydes induced by tin (IV) chloride
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Treatment of (S)-4-benzyloxypent-(2E)-2-enyl(tributyl)stannane (3) with tin (IV) chloride at -78°C, followed by the addition of an aldehyde, gives 1,5-diol derivatives (6) with excellent 1,5-diastereoselectivity.
- McNeill,Thomas
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p. 6239 - 6242
(2007/10/02)
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- Stereoselective Synthesis of 1- and 2-O-α-D-Cellotriosyl-3-deoxy-2(R)- and 2(S)-glycerols Related to Rhynchosporoside
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The stereoselective synthesis of 1- and 2-O-α-D-cellotriosyl-3-deoxy-2(R)- and 2(S)-glycerols, which determined the structure of rhynchosporoside produced by Rhynchosporium secalis, and their phytotoxicity toward the host plant (Hordeum vulgare) are described in detail.
- Sugawara, Fumio,Nakayama, Haruhiko,Stroebel, Gary A.,Ogawa, Tomoya
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p. 2261 - 2272
(2007/10/02)
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- MICROBIAL REDUCTION OF 2-PHENYLPROPIONIC ACID, 2-BENZYLOXYPROPIONIC ACID AND 2-(2-FURFURYL)PROPIONIC ACID
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Racemic 2-phenylpropionic acid and 2-benzyloxypropionic acid were subjected to microbial reduction and simultaneous resolution with several molds. i. e., Malus and Prunus strains of Glomerella cingulata, Gloeosporium olivarum and Gloeosporium laeticolor, yielding (R)-2-phenylpropanol and (S)-2-benzyloxypropanol , and leaving (R)-2-phenylpropionic acid , respectively.The microbial reduction of racemic 2-(2-furfuryl)propionic acid gave optically inactive (+/-)-2-(2-furfuryl)propanol .Keywords- asymetric reduction; 2-benzyloxypropionic acid; 2-(2-furfuryl)prioionic acid; microbial reduction; microbial resolution; 2-phenylpropionic acid
- Tsuda, Yoshiko,Kawai, Ken-Ichi,Nakajima, Shoichi
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p. 4657 - 4661
(2007/10/02)
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- Acyclic Stereoselection. 32. Synthesis and Characterization of the Diastereomeric (4S)-Pentane-1,2,3,4-tetrols.
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The stereochemistry of the reaction of the lithium enolate of ester 1 and ketene acetal 3 with aldehyde 2 jas been investigated.The diastereomeric (4S)-pentane-1,2,3,4-tetrols and their corresponding tetraacetate esters have been prepared and characterize
- Takai, Kazuhiko,Heathcock, Clayton H.
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p. 3247 - 3251
(2007/10/02)
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