- Method for preparing chiral nitrogen-phosphorus ligand L-8 containing pyridocyclopentane
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The invention discloses a method for preparing chiral nitrogen-phosphorus ligand L-8 containing pyridocyclopentane, and belongs to the technical field of medical intermediate chiral ligands. The chiral nitrogen-phosphorus L-8 ligand is prepared from cyclopentanone through the steps of addition, cyclization, chlorination, asymmetric boronation, oxidation, coupling, esterification and the like in sequence, large-scale preparation is relatively easy to achieve through the route, and the defect that in a traditional route, the yield is low in the first step of ring closing reaction and chiral alcohol preparation is overcome, and by selecting a proper chiral ligand, and combining with butyl lithium, asymmetric synthesis of chiral alcohol is realized, and a chiral separation column mode adoptedin literature is avoided.
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Paragraph 0008; 0036-0040
(2021/03/23)
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- Method for synthesizing chiral nitrogen-phosphorus ligand L-8 containing pyridocycloheptane
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The invention discloses a method for synthesizing a chiral nitrogen-phosphorus ligand L-8 containing pyridocycloheptane, and belongs to the technical field of medical intermediate chiral ligands. Thechiral nitrogen-phosphorus L-8 ligand is prepared from cyclopentanone through the steps of addition, cyclization, chlorination, asymmetric boronation, oxidation, coupling, esterification and the likein sequence, large-scale preparation is relatively easy to achieve through the route, and the defect that in a traditional route, the yield is low in the first step of ring closing reaction and chiralalcohol preparation, and by selecting a proper chiral ligand, and combining with butyl lithium, asymmetric synthesis of chiral alcohol is realized, and a chiral separation column mode adopted in literature is avoided.
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Paragraph 0036-0040
(2021/03/23)
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- Ytterbium-Catalyzed Intramolecular [3 + 2] Cycloaddition based on Furan Dearomatization to Construct Fused Triazoles
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The 1,2,3-triazole-containing polycyclic architecture widely exists in a broad spectrum of synthetic bioactive molecules, and the development of expeditious methods to synthesize these skeletons remains a challenging task. In this work, the catalytic cyclization of biomass-derived 2-furylcarbinols with an azide to form fused triazoles is described. This approach takes advantage of a single catalyst Yb(OTf)3 and operates via a furfuryl-cation-induced intramolecular [3 + 2] cycloaddition/furan ring-opening cascade.
- Xu, Xiaoming,Zhong, Ying,Xing, Qingzhao,Gao, Ziwei,Gou, Jing,Yu, Binxun
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supporting information
p. 5176 - 5181
(2020/07/14)
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- Gold(I)-Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to (±)-Laurokamurene B and the Skeletons of the Cycloaurenones and Dysiherbols
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The formal (3+2) cycloaddition between terminal allenes and aryl or styryl gold(I) carbenes generated by a retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes led to indenes and cyclopentadienes, respectively. These cycloaddition processes have been applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols as well as to the total synthesis of (±)-laurokamurene B.
- Yin, Xiang,Mato, Mauro,Echavarren, Antonio M.
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supporting information
p. 14591 - 14595
(2017/10/18)
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- Palladium-Catalyzed Aerobic Oxidative Cyclization of Aliphatic Alkenyl Amides for the Construction of Pyrrolizidine and Indolizidine Derivatives
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An efficient palladium-catalyzed aerobic oxidative cyclization has been developed to synthesize a variety of pyrrolizidine and indolizidine derivatives from simple aliphatic alkenyl amides in moderate to good yields. The reaction features the capability of accessing various N-heterocycles and the use of molecular oxygen (1 atm) as the green oxidant.
- Lo, Kai-Yip,Ye, Liu,Yang, Dan
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supporting information
p. 1570 - 1575
(2017/08/11)
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- Regio- and stereoselective synthesis of chiral nitrilolactones using Baeyer–Villiger monooxygenases
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This work describes the regio- and enantioselective synthesis of nitrile-containing chiral lactones from easily accessible ketone precursors using Baeyer–Villiger monooxygenases. These biocatalysts controlled the distribution of regioisomers much more tightly than commonly used stoichiometric reagents, additionally with good to excellent optical purity of products. A surprising case of strong stereoelectronic control was also observed. We tested a library of 14 catalysts using five-to eight-membered cyclic ketones with two different tether lengths to the nitrile group. In all but the largest series we found suitable wild-type enzymes for preparative scale synthesis of the target compounds. The diverse possibilities to further functionalize lactones and nitriles make this method interesting for the generation of chiral building blocks.
- Fink, Michael J.,Snajdrova, Radka,Winninger, Alexander,Mihovilovic, Marko D.
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p. 7241 - 7248
(2016/10/26)
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- Enantioselective oxidation by a cyclohexanone monooxygenase from the xenobiotic-degrading Polaromonas sp. strain JS666
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A cyclohexanone monooxygenase (CHMO) from the xenobiotic-degrading Polaromonas sp. strain JS666 was heterologously expressed in Escherichia coli, and its ability to catalyze enantio- and regiodivergent oxidations of prochiral and racemic ketones was investigated. The expression system was also used to evaluate this enzyme's potential role in the oxidation of cis-1,2-dichloroethene (cDCE), a groundwater pollutant for which strain JS666 is the only known assimilator. The substrate enantiopreference and -selectivity of the strain JS666 CHMO is similar to that of other CHMO-type enzymes; of note is this enzyme's excellent stereodiscrimination of 2-substituted cyclic ketones. The expression system exhibits no activity with ethene or cDCE as substrates under the tested conditions. Phylogenetic analysis shows that sequence variability among cyclohexanone monooxygenases could be a rich source of new enzyme activities and attributes.
- Alexander, Anne K.,Biedermann, David,Fink, Michael J.,Mihovilovic, Marko D.,Mattes, Timothy E.
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experimental part
p. 105 - 110
(2012/07/28)
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- Effects of phosphorus substituents on reactions of α- alkoxyphosphonium salts with nucleophiles
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The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph3P with Grignard reagents was observed to take place in the presence of O2 to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments. A dramatic change in the reactivity of an α-alkoxyphosphonium salt toward nucleophiles is observed due to the steric and electronic nature of the phosphine substituents. By changing the type of phosphorus substituents, the reaction pathway can be controlled to proceed selectively by substitution or a new radical reaction (see scheme; OTf=trifluoromethansulfonate, TMS=trimethylsilyl, o-tol=tolyl). Copyright
- Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Sawama, Yoshinari,Maegawa, Tomohiro,Fujioka, Hiromichi
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supporting information
p. 11423 - 11432
(2012/11/07)
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- Induced allostery in the directed evolution of an enantioselective Baeyer-Villiger monooxygenase
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The molecular basis of allosteric effects, known to be caused by an effector docking to an enzyme at a site distal from the binding pocket, has been studied recently by applying directed evolution. Here, we utilize laboratory evolution in a different way, namely to induce allostery by introducing appropriate distal mutations that cause domain movements with concomitant reshaping of the binding pocket in the absence of an effector. To test this concept, the thermostable Baeyer-Villiger monooxygenase, phenylacetone monooxygenase (PAMO), was chosen as the enzyme to be employed in asymmetric Baeyer-Villiger reactions of substrates that are not accepted by the wild type. By using the known X-ray structure of PAMO, a decision was made regarding an appropriate site at which saturation mutagenesis is most likely to generate mutants capable of inducing allostery without any effector compound being present. After screening only 400 transformants, a double mutant was discovered that catalyzes the asymmetric oxidative kinetic resolution of a set of structurally different 2-substituted cyclohexanone derivatives as well as the desymmetrization of three different 4-substituted cyclohexanones, all with high enantioselectivity. Molecular dynamics (MD) simulations and covariance maps unveiled the origin of increased substrate scope as being due to allostery. Large domain movements occur that expose and reshape the binding pocket. This type of focused library production, aimed at inducing significant allosteric effects, is a viable alternative to traditional approaches to designed directed evolution that address the binding site directly.
- Wu, Sheng,Acevedo, Juan Pablo,Reetz, Manfred T.
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experimental part
p. 2775 - 2780
(2010/10/03)
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- Diastereoselectivity control of the radical carboazidation of substituted methylenecyclohexanes
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A systematic study of the diastereoselectivity of the radical carboazidation of methylenecyclohexane derivatives is presented. Several substitution patterns leading to a high level of stereocontrol have been identified. Axial attack is the preferred reaction pathway for cyclohexyl radicals, and excellent stereoselectivities can be obtained by introducing an axial substitutent at position 2. In this case, a second equatorial substituent at position 2 may be tolerated without a large detrimental effect on the diastereoselectivity. Finally, a high level of equatorial attack is observed with a very bulky substituent at position 2.
- Cren, Sylvaine,Schar, Pascal,Renaud, Philippe,Schenk, Kurt
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supporting information; experimental part
p. 2942 - 2946
(2009/09/06)
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- Laboratory evolution of robust and enantioselective Baeyer-Villiger monooxygenases for asymmetric catalysis
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The Baeyer-Villiger Monooxygenase, Phenylacetone Monooxygenase (PAMO), recently discovered by Fraaije, Janssen, and co-workers, is unusually thermostable, which makes it a promising candidate for catalyzing enantioselective Baeyer-Villiger reactions in organic chemistry. Unfortunately, however, its substrate scope is very limited, reasonable reaction rates being observed essentially only with phenylacetone and similar linear phenyl-substituted analogs. Previous protein engineering attempts to broaden the range of substrate acceptance and to control enantioselectivity have been met with limited success, including rational design and directed evolution based on saturation mutagenesis with formation of focused mutant libraries, which may have to do with complex domain movements. In the present study, a new approach to laboratory evolution is described which has led to mutants showing unusually high activity and enantioselectivity in the oxidative kinetic resolution of a variety of 2-aryl and 2-alkylcyclohexanones which are not accepted by the wild-type (WT) PAMO and of a structurally very different bicyclic ketone. The new strategy exploits bioinformatics data derived from sequence alignment of eight different Baeyer-Villiger Monooxygenases, which in conjunction with the known X-ray structure of PAMO and induced fit docking suggests potential randomization sites, different from all previous approaches to focused library generation. Sites harboring highly conserved proline in a loop of the WT are targeted. The most active and enantioselective mutants retain the high thermostability of the parent WT PAMO. The success of the "proline" hypothesis in the present system calls for further testing in future laboratory evolution studies.
- Reetz, Manfred T.,Wu, Sheng
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supporting information; experimental part
p. 15424 - 15432
(2010/02/16)
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- Are oxazolidinones really unproductive, parasitic species in proline catalysis? - Thoughts and experiments pointing to an alternative view
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The N,O-acetal and N,O-ketal derivatives (oxazolidinones) formed from proline, and aldehydes or ketones are well-known today, and they are detectable in reaction mixtures involving proline catalysis, where they have been considered 'parasitic dead ends'. We disclose results of experiments performed in the early 1970's, and we describe more recent findings about the isolation, characterization, and reactions of the oxazolidinone derived from proline and cyclohexanone. This oxazolidinone reacts (THF, room temperature) with the electrophiles β-nitrostyrene and chloral (=trichloroacetaldehyde), to give the Michael and aldol adduct, respectively, after aqueous workup (Scheme 5). The reactions occur even at -75° when catalyzed with bases such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or EtN(i-Pr)2 (DIPEA) (10%; Table 1). It is shown by NMR (Figs. 1 and 3) and IR analysis (Figs. 2 and 4) that the primarily detectable product (before hydrolysis) of the reaction with the nitro-olefin is again an oxazolidinone. When dissolved in hydroxylic solvents such as MeOH, 'hexafluoroisopropanol' ((CF3) 2CHOH; HFIP), AcOH, CF3COOH, or in LiBr-saturated THF, the ring of the oxazolidinone from cyclohexanone and proline opens up to the corresponding iminium ion (Tables 2-4), and when treated with strong bases such as DBU (in (D8)THF) the enamino-carboxylate derived from proline and cyclohexanone is formed (Scheme 8). Thus, the two hitherto putative participants (iminium ion and enamine) of the catalytic cycle (Scheme 9) have been characterized for the first time. The commonly accepted mechanism of the stereoselective C,C- or C,X-bond-forming step (i.e., A-D) of this cycle is discussed and challenged by thoughts about an alternative model with a pivotal role of oxazolidinones in the regio- and diastereoselective formation of the intermediate enamino acid (by elimination) and in the subsequent reaction with an electrophile (by trans-addition with lactonization; Schemes 11-14). The stereochemical bias between endo- and exo-space of the bicyclo[3.3.0]octane-type oxazolidinone structure (Figs. 5 and 6) is considered to possibly be decisive for the stereochemical course of events. Finally, the remarkable consistency, with which the diastereotopic Re-face of the double bond of pyrrolidino-enamines (derived from proline) is attacked by electrophiles (Schemes 1 and 15), and the likewise consistent reversal to the Si-face with bulky (Aryl) 2C-substituents on the pyrrolidine ring (Scheme 16) are discussed by invoking stereoelectronic assistance from the lone pair of pyramidalized enamine N-atoms.
- Seebach, Dieter,Beck, Albert K.,Badine, D. Michael,Limbach, Michael,Eschenmoser, Albert,Treasurywala, Adi M.,Hobi, Reinhard,Prikoszovich, Walter,Linder, Bernard
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p. 425 - 471
(2008/02/07)
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- A mild, chemoselective protocol for the removal of thioketals and thioacetals mediated by Dess-Martin periodinane.
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[reaction: see text] This paper describes the development of a useful procedure for the removal of thioacetals and thioketals using Dess-Martin periodinane (DMP) reagent. In contrast to existing methods, this protocol offers general reactivity, compatibility with a wide range of functional groups, and convenient reaction times. Also discussed are chemoselectivity experiments involving functionalities that may be subject to oxidation by DMP, qualitative effects of substrate on hydrolysis rate, and direct thioacetal to acetal conversions.
- Langille, Neil F,Dakin, Les A,Panek, James S
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p. 575 - 578
(2007/10/03)
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- Orally active, water-soluble antimalarial 3-aryltrioxanes: Short synthesis and preclinical efficacy testing in rodents
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Short chemical syntheses of four new antimalarial trioxanes are presented, starting with inexpensive and commercially available cyclohexanone. Almost exclusive formation of the trioxane 12α-stereoisomers simplifies product purification. Carboxyphenyltrioxanes 3 and 5 are thermally stable in air even at 60°C for 24 h. When administered orally, these new carboxyphenyltrioxanes are highly efficacious in curing malaria-infected mice. Important for their practical in vivo administration, these new synthetic antimalarial trioxanes 3 and 5 are 14-20 times more soluble in water at pH 7.4 than is artelinic acid (1), a leading semisynthetic, herb-derived antimalarial trioxane drug candidate.
- Posner, Gary H.,Jeon, Heung Bae,Ploypradith, Poonsakdi,Paik, Ik-Hyeon,Borstnik, Kristina,Xie, Suji,Shapiro, Theresa A.
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p. 3824 - 3828
(2007/10/03)
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- Efficient and scaleable methods for ω-functionalized nonanoic acids: Development of a novel process for azelaic and 9-aminononanoic acids (nylon-6,9 and nylon-9 precursors)
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A new, convergent synthesis and process of the title open-chain C-9 compounds, valuable monomers for preparation of polyamides with specific properties, are discussed. Starting from relatively inexpensive raw materials, for example, cyclohexanone and activated C-3 olefins, the method provides polymer grade co-functionalized nonanoic acids. An improved protocol for cyanoethylation or carbalkoxyethylation of cyclohexanone in the presence of a catalytic amount of primary or secondary amines gave 3-(2-oxo-cyclohexane) propanecarboxylic acid derivatives 1 in high yield. Cyclohexaneperoxycarboxylic acid (CHPCA) is introduced as highly efficient reagent in Baeyer-Villiger rearrangement of 1. Pyrolysis of 2 (EWG = CN) afforded under optimized conditions 3 in high yield and regioisomeric purity, otherwise a mixture of three unsaturated isomeric ω-cyano nonenoic acids is obtained. Partial hydrogenation of unsaturated acids 3 allowed isolation of saturated long-chain difunctionalized acids 4. Hydrolysis of 4 led to 1,9-nonanedicarboxylic acid (azelaic acid) 5, whereas its hydrogenation at elevated pressure gave 9-aminononanoic acid 6. Alternatively, a practical four-step syntehsis of 5 via isolable 7-substituted oxepan-2-one (EWG = COOMe) 2 has been designed and experimentated. The versatile position of 3-(2-oxo-cyclohexane) propanecarboxylic acid derivatives 1 as raw materials for Fine Chemicals is also discussed.
- Cotarca, Livius,Delogu, Pietro,Nardelli, Alfonso,Maggioni, Paolo,Bianchini, Roberto,Sguassero, Stefano,Alini, Stefano,Dario, Roberto,Clauti, Giuliano,Pitta, Giorgio,Duse, Gianpaolo,Goffredi, Fabrizio
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- Asymmetric syntheses of enantiomeric 3-p-fluorophenyl 1,2,4-trioxane analogues of the antimalarial artemisinin
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We have devised an asymmetric synthesis of chiral artemisinin analogues (+)-4a and (-)-4a that retain the tricyclic ring system found in the natural product. The key step in the preparation of (+)-4a involves an asymmetric MgCl2 promoted Michael addition of the (R)-(-)pyrrolidinemethanol-derived enamine 8 to acrylonitrile. This gives the corresponding ketone 9 in 50% yield (>95% ee). Subsequent elaboration of 9 provides the trioxane target (+)-4a in greater than 85% ee. Enantiomeric trioxane (-)-4a was prepared in a similar manner using (S)-(+)-pyrrolidinemethanol in the first step of the sequence.
- O' Neill, Paul M.,Miller, Alison,Bickley, Jamie F.,Scheinmann, Feodor,Oh, Chang Ho,Posner, Gary H.
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p. 9133 - 9136
(2007/10/03)
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- Efficient synthesis of ω-functionalized nonanoic acids
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Starting from cyclohexanone and acrylonitrile, a four-step synthesis of the title open-chain C9 compounds is reported. An improved protocol for cyanoethylation of cyclohexanone in the presence of a catalytic amount of cyclohexylamine afforded 3-(2-oxocyclohexyl)propanenitrile (1) in 92% yield. Cyclohexaneperoxycarboxylic acid (CHPCA) is introduced as a highly efficient reagent in the Baeyer-Villiger rearrangement of 1, yielding over 90% of 2. Pyrolysis of 2 afforded under optimized conditions 3 in 92% yield and 99% regioisomeric purity, otherwise a mixture of three unsaturated isomeric ω-cyano nonenoic acids 3, 10 and 11 is obtained. Partial hydrogenation of 3 allowed the isolation of 4 in 90% yield. Hydrogenation of 4 at elevated hydrogen pressure gave 9-aminononanoic acid (5), whereas hydrolysis of 4 led to 1,9-nonanedioic acid (azelaic acid, 6). Both, 5 and 6 are valuable C9 monomers for the preparation of polyamides with specific properties.
- Cotarca,Delogu,Maggioni,Nardelli,Bianchini,Sguassero
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p. 328 - 332
(2007/10/03)
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- Clay catalysis: Storks alkylation and acylation of cyclohexanone without isolation of enamine
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Cyclohexanone and morpholine in the presence of KSF under azeotropic distillation gave 1-morpholinocyclohexane which is alkylated or acylated in situ without isolation of the enamine. The overall yield of these Stork's reactions are better or equivalent to those obtained by isolation of the enamine.
- Hammadi,Villemin
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p. 2901 - 2904
(2007/10/03)
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- STEREOSELECTIVE SYNTHESIS OF THE TRICYCLIC CONDENSED DERIVATIVES OF THIAZOLIDINE
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The perhydro derivatives of thiazoloquinoline, thiazolocyclopentapyridine, thiazoloindole, and cyclopentapyrrolothiazole and also their 2-methyl derivatives were synthesized by the addition of thiirane and methylthiirane at the C=N bond in bicyclic imines of the 2,3,4,4a,5,6,7,8-octahydroquinoline type.An alternative method involves reaction of the thiiranes with amino ketones of the 2,2-ethylenedioxycyclohexylpropylamine type, protected at the carbomyl group, followed by acid deblocking and cyclization by treatment with alkali.The last method is the only method for the production of perhydrocyclopentapyrrolothiazoles, since 2,3,3a,4,5,6-hexahydrocyclopentapyrrole is not a stable imine.Some of the compounds were obtained in the form of single diastereomers, the configurations of which for the two subjects were determined by NMR.In other cases mixtures of the stereoisomers are formed with a srtong preponderance of one of them; arguments concerning their configurations are presented.It is shown that both methods of synthesis lead to an identical stereochemical result.
- Sokolov, V. V.,Potekhin, A. A.,Ovchinnikova, I. V.,Gindin, V. A.,Smirnov, S. N.
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p. 582 - 589
(2007/10/02)
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- Ruthenium-Catalyzed Hydration of Nitriles and Transformation of δ-Ketonitriles to Ene-lactams: Total Synthesis of (-)-Pumiliotoxin C
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Hydration of nitriles with 1-2 equivalents of water can be performed efficiently by using RuH2(PPh3)4 catalyst to give the corresponding amides.Under the similar reaction conditions, δ-ketonitriles can be converted into the corresponding ene-lactams, which are versatile synthetic intermediates.The efficiency of the reaction is demonstrated by the short-step synthesis of (-)-pumiliotoxin C.
- Murahashi, Shun-Ichi,Sasao, Shigehiro,Saito, Eiichiro,Naota, Takeshi
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p. 8805 - 8826
(2007/10/02)
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- A SIMPLE METHOD FOR DETHIOACETALIZATION
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Thioacetals and thioketals can be cleaved to carbonyl compounds in high yieeds by treatment with bis (trifluoroacetoxyiodobenzene)
- Stork, Gilbert,Zhao, Kang
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p. 287 - 290
(2007/10/02)
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- New Reagents: Part 5 - Aluminium Chloride-Sodium Iodide System as a Highly Selective Reagent for Non-hydrolytic Cleavage of Esters
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Aluminium chloride-sodium iodide is found to be a highly selective reagent for non-hydrolytic cleavage of esters.This reagent is almost ineffective towards phenyl esters and aryl alkyl ethers.
- Bhatt, M. Vivekananda,Setty, K. S. Sundara
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p. 467 - 468
(2007/10/02)
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- Synthesis of Ketones by Cyclization of Cyano and Acetylenic Radicals: Use of δ-Hydroxy Nitriles and δ- or ε-Hydroxy Acetylenes
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The radical intermediates generated by deoxygenation of alcohols undergo intramolecular ring closure when suitably located triple bonds (CC or CN) are present; the reaction provides a new synthesis of bicyclic ketones from either monocyclic ketones or cyclic olefins.
- Clive, Derrick L. J.,Beaulieu, Pierre L.,Set, Lu
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p. 1313 - 1314
(2007/10/02)
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- Process for producing difunctional aliphatic organic compounds
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Process industrially and economically useful for preparing difunctional aliphatic organic compounds of formula in which n=6,7, X=--COOH, --COOR, Y=--CN, --COOH, --CONH2, --CH2 --NH2 --COOR wherein R is a linear or branched alkyl containing 1-6 carbon atoms. The process starts from a ketone of the formula STR1 in which n=2,3 and R1 =--CN, --COOH. The ketone (I) is changed to the corresponding hydroperoxide by means of H2 O2, the hydroperoxide is catalytically split by means of a catalyst Fe++ /Cu++ to give an unsaturated acid of the formula and this is catalytically hydrogenated to the compound When R1 is different from Y, R1 is changed to Y through known methods.
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- Enamine Chemistry. Part 27. The Effect of Additional α- and β-Heteroatoms on the p?-Conjugation and Reactivity of Enamines. Sub- or Super-Enamines?
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Enamines derived from isoxazolidine and 1,3-dioxa-5-azacyclohexane have been prepared.The effect of the addition a α- or β-heteroatoms is to decrease the p?-conjugation between the nitrogen lone pair of electrons and the ?-electrons of the double bond, as reflected in the spectral properties of the enamines and their reactivity with electrophiles.The reasons for this are discussed.
- Ahmed, Md. Giasuddin,Ahmed, S. Asghari,Hickmott, Peter W.
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p. 2383 - 2386
(2007/10/02)
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