- Regio- and Enantioselective Properties of the Lipase-catalyzed Irreversible Transesterification of Some 2-Substituted-1,4-Butanediols in Organic Solvents
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The regioselectivity of the Pseudomonas fluorescens (P. cepacia) lipase (PFL)-catalyzed irreversible transesterification of 2-substituted-1,4-butanediols 1a-3a has been studied and, in the case of 3a, it has been shown that (R)- and (S)-diols are acylated
- Ferraboschi, Patrizia,Casati, Silvana,Verza, Elisa,Santaniello, Enzo
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- Palladium-Catalyzed Asymmetric Hydroesterification of α-Aryl Acrylic Acids to Chiral Substituted Succinates
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A palladium-catalyzed asymmetric hydroesterification of α-aryl acrylic acids with CO and alcohol was developed, preparing a variety of chiral α-substituted succinates in moderate yields with high ee values. The kinetic profile of the reaction progress revealed that the alkene substrate first underwent the hydroesterification followed by esterification with alcohol. The origin of the enantioselectivity was elucidated by density functional theory computation.
- Ji, Xiaolei,Shen, Chaoren,Tian, Xinxin,Dong, Kaiwu
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supporting information
p. 8645 - 8649
(2021/10/25)
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- Photocatalytic acyl azolium-promoted alkoxycarbonylation of trifluoroborates
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Despite recent advancements in the selective generation and coupling of organic radical species, the alkoxycarbonyl radical remains underexplored relative to other carbon-containing radical species. Drawing inspiration from new strategies for generating acyl radical equivalents utilizing dual N-heterocyclic carbene catalysis and photocatalysis, we have prepared dimethylimidazolium esters that can function as an alkoxycarbonyl radical surrogate under photocatalytic conditions. We demonstrate the synthetic utility of these azolium-based partners through the preparation of esters arising from the coupling of this radical surrogate with an oxidatively generated alkyl radical.
- Scheidt, Karl A.,Zhu, Joshua L.
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- Synergetic Catalysis for One-pot Bis-alkoxycarbonylation of Terminal Alkynes over Pd/Xantphos?Al(OTf)3 Bi-functional Catalytic System
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Tandem bis-alkoxycarbonylation of alkynes allows for the preparation of 2-substituted succinates from alkynes and nucleophile alcohol via two successive alkoxycarbonylation with advantages of 100 % atomic economy and simplified one-pot operation. Herein, the one-pot tandem bis-alkoxycarbonylation of alkynes was accomplished over the bi-functional catalytic system containing Xantphos-modified Pd-complex and Lewis super-acid of Al(OTf)3. It was found that, via the synergetic catalysis, the involved Xantphos-modified Pd-complex was responsible for the activation of CO and the alkynes through coordination to Pd-center while Al(OTf)3 was in charge of the activation of the alcohol to facilitate the formation of [Pd?H]+ active species. The in situ high-pressure FT-IR analysis, coupled with 1H/13C NMR spectral characterizations, confirmed that the introduced Al(OTf)3 with intensive oxophilicity (via acid-base pair interaction) was able to activate nucleophilic MeOH to be a reliable proton-donor (i. e. hydride-source) to warrant the formation and stability of [Pd?H]+ species upon the oxidation of Pd0 by H+ (Pd0+H+→[PdII?H]+). Over the developed bi-functional catalytic system, the yields of the target diesters were obtained in the range of 36~86 % in this sequence with the wide substrate scope.
- Guo, Wen-Di,Liu, Lei,Yang, Shu-Qing,Chen, Xiao-Chao,Lu, Yong,VO-Thanh, Giang,Liu, Ye
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p. 1376 - 1384
(2020/01/24)
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- Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers
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The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.
- Ponra, Sudipta,Rabten, Wangchuk,Yang, Jianping,Wu, Haibo,Kerdphon, Sutthichat,Andersson, Pher G.
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p. 13878 - 13883
(2018/10/24)
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- Co-catalysis over a bi-functional ligand-based Pd-catalyst for tandem bis-alkoxycarbonylation of terminal alkynes
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A bi-functional ligand (L1) containing a diphosphino fragment and sulfonic acid group (-SO3H) enabled PdCl2(MeCN)2 to efficiently catalyze the tandem bis-alkoxycarbonylation of terminal alkynes to produce aryl-/alkyl-substituted succinate (α,ω-diesters). It was found that the -SO3H incorporated in L1 indispensably assisted the Pd-catalyst in accomplishing this tandem reaction via intramolecular synergic effects. Co-catalysis over the L1-based Pd-catalyst was not due to the physical mixture of Xantphos and MeSO3H. In situ FTIR analysis verified that the formation and stability of Pd-H active species were facilitated by the presence of L1. The formation of stabilized diacylpalladium intermediate (F) was the critical driving force for the second-step methoxycarbonylation. DFT calculation was carried out to optimize the geometric structure of F, which indicated that the developed intramolecular O?H hydrogen bonds were an important structural feature to stabilize F. In addition, the L1-based Pd-catalyst could be recycled successfully for at least 3 runs in the ionic liquid [Bmim]NTf2 without obvious activity loss and detectable metal leaching.
- Yang, Da,Liu, Huan,Wang, Dong-Liang,Luo, Zhoujie,Lu, Yong,Xia, Fei,Liu, Ye
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p. 2588 - 2595
(2018/06/11)
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- Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy
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The NHC-catalyzed transformation of unsaturated aldehydes into saturated esters through an organocatalytic homoenolate process has been thoroughly studied. Leveraging a unique “Umpolung”-mediated β-protonation, this process has evolved from a test bed for homoenolate reactivity to a broader platform for asymmetric catalysis. Inspired by our success in using the β-protonation process to generate enals from ynals with good E/Z selectivity, our early studies found that an asymmetric variation of this reaction was not only feasible, but also adaptable to a kinetic resolution of secondary alcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach through inclusion of a hydrogen bond donor cocatalyst significantly improved enantioselectivity.
- Wang, Michael H.,Barsoum, David,Schwamb, C. Benjamin,Cohen, Daniel T.,Goess, Brian C.,Riedrich, Matthias,Chan, Audrey,Maki, Brooks E.,Mishra, Rama K.,Scheidt, Karl A.
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p. 4689 - 4702
(2017/05/12)
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- Reprint of: Impact of the corrin framework of vitamin B12 on the electrochemical carbon-skeleton rearrangement in comparison to an imine/oxime planar ligand; tuning selectivity in 1,2-migration of a functional group by controlling electrolysis potential
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Among the coenzyme B12-dependent enzymes, methylmalonyl-CoA mutase (MMCM) catalyzes the carbon-skeleton rearrangement reaction between R-methylmalonyl-CoA and succinyl-CoA. Diethyl 2-bromomethyl-2-phenylmalonate, an alkyl bromide substrate having two different migrating groups (phenyl and carboxylic ester groups) on the β-carbon, was applied to the electrolysis mediated by a hydrophobic vitamin B12 model complex, heptamethyl cobyrinate perchlorate in this study. The electrolysis of the substrate at ? 1.0 V vs. Ag-AgCl by light irradiation afforded the simple reduced product (diethyl 2-methyl-2-phenylmalonate) and the phenyl migrated product (diethyl 2-benzyl-2-phenylmalonate), as well as the electrolysis of the substrate at ? 1.5 V vs. Ag-AgCl in the dark. The electrolysis of the substrate at ? 2.0 V vs. Ag-AgCl afforded the carboxylic ester migrated product (diethyl phenylsuccinate) as the major product. The selectivity for the migrating group was successfully tuned by controlling the electrolysis potential. We clarified that the cathodic chemistry of the Co(III) alkylated heptamethyl cobyrinate is critical for the selectivity of the migrating group through mechanistic investigations and comparisons to the simple vitamin B12 model complex, an imine/oxime-type cobalt complex.
- Abe, Masaaki,Hisaeda, Yoshio,Pan, Ling,Shimakoshi, Hisashi,Tahara, Keishiro,Yamaguchi, Ryoko
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p. 438 - 443
(2017/10/23)
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- Enantioselective β-Protonation by a Cooperative Catalysis Strategy
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An enantioselective N-heterocyclic carbene (NHC)-catalyzed β-protonation through the orchestration of three distinct organocatalysts has been developed. This cooperative catalyst system enhances both yield and selectivity, compared to only the NHC-catalyz
- Wang, Michael H.,Cohen, Daniel T.,Schwamb, C. Benjamin,Mishra, Rama K.,Scheidt, Karl A.
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p. 5891 - 5894
(2015/05/27)
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- Synthesis of α-aryl esters and nitriles: Deaminative coupling of α-aminoesters and α-aminoacetonitriles with arylboronic acids
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Transition-metal-free synthesis of α-aryl esters and nitriles using arylboronic acids with α-aminoesters and α-aminoacetonitriles, respectively, as the starting materials has been developed. The reaction represents a rare case of converting C(sp3)-N bonds into C(sp3)-C(sp2) bonds. The reaction conditions are mild, demonstrate good functional-group tolerance, and can be scaled up. Touch base: A transition-metal-free protocol for the synthesis of α-aryl esters and nitriles by deaminative coupling is presented. Strong bases and transition-metal catalysts are not needed. The new synthetic method uses readily available starting materials and demonstrates wide substrate scope.
- Wu, Guojiao,Deng, Yifan,Wu, Chaoqiang,Zhang, Yan,Wang, Jianbo
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supporting information
p. 10510 - 10514
(2016/02/18)
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- Preparation of chiral 3-arylpyrrolidines via the enantioselective 1,4-addition of arylboronic acids to fumaric esters catalyzed by Rh(I)/chiral diene complexes
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A highly efficient rhodium-catalyzed protocol for the preparation of 2-arylsuccinic esters and 3-arylpyrrolidines of high optical purity has been achieved. In the presence of 1 mol % of a chiral diene/Rh(I) catalyst, asymmetric addition of various arylbor
- Chung, Yu-Chiang,Janmanchi, Damodar,Wu, Hsyueh-Liang
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supporting information; experimental part
p. 2766 - 2769
(2012/07/17)
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- Highly enantioselective iridium-catalyzed hydrogenation of α,β-unsaturated esters
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α,β-Unsaturated esters have been employed as substrates in iridium-catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic- and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals. Asymmetric hydrogenation: A variety of α,β-unsaturated esters were hydrogenated with high enantioselectivities (see scheme). The hydrogenated products have been used in synthetic transformations as well as in formal total syntheses. Copyright
- Li, Jia-Qi,Quan, Xu,Andersson, Pher G.
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supporting information
p. 10609 - 10616
(2012/11/07)
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- Synthesis of a γ-lactam library via formal cycloaddition of imines and substituted succinic anhydrides
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Formal cycloaddition reactions between imines and cyclic anhydrides serve as starting point for the synthesis of diverse libraries of small molecules. The synthesis of succinic anhydrides substituted with electron-withdrawing groups is facilitated by new mild conditions for alkylation of aryl-substituted acetyl esters with ethyl bromoacetate. These anhydrides are then used in formal cycloaddition reactions with imines to produce γ-lactams. 2-Fluoro-5-nitrophenylsuccinic anhydride reacts efficiently with imines to provide lactams that are further diversified by conversion of the nitro group to either an aniline and an azide for subsequent reactions with acylating agents and alkynes, respectively. The synthesis of cyanosuccinic anhydride is reported for the first time, and the use of this compound in reactions with imines and subsequent functionalization of the resultant lactams is demonstrated.
- Tan, Darlene Q.,Atherton, Amy L.,Smith, Austin J.,Soldi, Cristian,Hurley, Katherine A.,Fettinger, James C.,Shaw, Jared T.
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scheme or table
p. 218 - 223
(2012/05/07)
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- DERIVATIVES OF 2-PYRIDIN-2-YL-PYRAZOL-3(2H)-ONE, PREPARATION AND THERAPEUTIC USE THEREOF AS HIF ACTIVATORS
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The present invention relates to novel substituted dihydropyrazolone derivatives, to their preparation and to their therapeutic use as activators of the transcription factor HIF.
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- Electrochemical catalytic carbon-skeleton rearrangement mediated by imine/oxime-type B12 model complex
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An electrochemical carbon-skeleton rearrangement of methylmalonate skeleton to succinate was successfully mediated by an imine/oxime-type cobalt complex using diethyl 2-bromomethyl-2- phenylmalonate as a model substrate of a coenzyme B12-dependent enzymatic reaction. Cyclic voltammetric and mass spectrometric studies revealed that this electrocatalysis of the alkyl bromide with 1,2-migration of a carboxylic ester group was achieved by the duet redox process between the reduction of the monoalkylated complex and the oxidation of the dialkylated complex.
- Tahara, Keishiro,Chen, Yi,Pan, Ling,Masuko, Takahiro,Shimakoshi, Hisashi,Hisaeda, Yoshio
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supporting information; experimental part
p. 177 - 179
(2011/04/14)
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- Practical synthesis of diethyl phenylsuccinate by Mg-promoted carboxylation of ethyl cinnamate
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Mg-promoted reduction of ethyl cinnamate (1a) in the presence of carbon dioxide gave a mixture of β-carboxylated compound 2a and α,β-dicarboxylated compound 3a. Similar reductive carboxylation of 1a followed by acidic decarboxylation of one of the two geminal carboxyl groups of the generated 3a and esterification afforded selective formation of diethyl phenylsuccinate (2a) in good yield.
- Maekawa, Hirofumi,Murakami, Taro,Miyazaki, Takeshi,Nishiguchi, Ikuzo
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supporting information; experimental part
p. 368 - 369
(2011/05/04)
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- Novel one-pot vicinal double C-acylation of styrenes and methacrylates by electroreduction
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Electroreduction of styrenes or alkyl methacrylates in the presence of aliphatic acid anhydrides or N-acylimidazoles with an undivided cell equipped with zinc electrodes as the anode and the cathode brought about novel one-pot vicinal double C-acylation to afford the corresponding 1,4-diketones in satisfactory yields.
- Yamamoto, Yoshimasa,Maekawa, Hirofumi,Goda, Satoshi,Nishiguchi, Ikuzo
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p. 2755 - 2758
(2007/10/03)
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- Silicone as an organosilicon reagent 2. Rhodium-catalyzed conjugate addition of the silicone reagent to α,β-unsaturated carbonyl compounds
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The reaction of poly(phenylmethylsiloxane) with α,β-unsaturated carbonyl compounds in the presence of aqueous K2CO3 and 3 mol% of [Rh(OH)(cod)]2 gives 1,4-conjugate addition product in good yields. Arylchlorosilanes also u
- Koike, Tooru,Du, Xiaoli,Mori, Atsunori,Osakada, Kohtaro
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p. 301 - 303
(2007/10/03)
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- Conjugate addition of arylsilanes to unsaturated carbonyl compounds catalyzed by rhodium in air and water
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ArSiCl3 and Ar2SiCl2, believed to be unstable in aqueous media, reacted efficiently with α,β-unsaturated ketones and esters in air and water (in the presence of sodium fluoride and a rhodium catalyst), giving good to excellent yields of the desired conjugate addition products.
- Huang,Li
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p. 2348 - 2349
(2007/10/03)
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- Rhodium catalyzed conjugated addition of unsaturated carbonyl compounds by triphenylbismuth in aqueous media and under an air atmosphere
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In the presence of a rhodium catalyst, α,β-unsaturated esters and ketones react with triphenylbismuth in aqueous media and under an air atmosphere to give the corresponding conjugated addition products in high yields.
- Venkatraman, Sripathy,Li, Chao-Jun
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p. 781 - 784
(2007/10/03)
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- Quasi-nature catalysis: Conjugated addition of unsaturated carbonyl compounds with aryl and vinyltin reagents catalyzed by rhodium in air and water
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In air and water, trialkylphenyl- or trialkylvinylstannanes react with α,β-unsaturated esters and ketones to give the corresponding conjugated addition products in high yields in the presence of a rhodium catalyst.
- Venkatraman, Sripathy,Meng, Yue,Li, Chao-Jun
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p. 4459 - 4462
(2007/10/03)
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- Asymmetric conjugate 1,4-addition of arylboronic acids to α,β-unsaturated esters catalyzed by rhodium(I)/(S)-binap
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Arylboronic acids underwent the conjugate 1,4-addition to α,β-unsaturated esters to give β-aryl esters in high yields in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yields and high enantioselectivity exceeding 90% ee in the presence of 3 mol % of Rh(acac)(C2H4)2 and (S)-binap at 100 °C. The rhodium/(S)-binap complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on α,β-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.
- Sakuma, Satoshi,Sakai, Masaaki,Itooka, Ryoh,Miyaura, Noria
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p. 5951 - 5955
(2007/10/03)
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- Monoamine Oxidase-Catalyzed Oxidative Rearrangement of trans,trans-1-(Aminomethyl)-2-methoxy-3-phenylcyclopropane
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trans,trans-1-(Aminomethyl)-2-methoxy-3-phenylcyclopropane (3) was synthesized in three steps from (Z)-β-methoxystyrene and ethyl diazoacetate. Compound 3 was shown to be a substrate and inactivator of mitochondrial beef liver monoamine oxidase (MAO) with
- Lu, Xingliang,Yang, Shengtian,Silverman, Richard B.
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p. 8961 - 8966
(2007/10/03)
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- OXIDATIVE CARBONYLATION OF STYRENE TO ETHYL CINNAMATE
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A detailed study was made of the products of oxidative carbonylation of styrene in the presence of the catalyst system PdCl2-CuCl2-Cu(OAc)2-Mn(OAc)2 at 100 deg C and 3.2 MPa.The target product, ethyl cinnamate, reached a molar proportion of 95percent.The principal side reaction products were acetophenone and diethylphenyl succinate.Investigation of the influence of the composition of the catalyst system on the yield of the target product and the selectivity of the reaction showed that Mn(OAc)2 was of greatest importance as a co-catalyst in the multicomponent Pd catalyst system.The results are discussed with reference to an alcoholate mechanism for oxidative carbonylation of olefins.Keywords: oxidative carbonylation, styrene, ethyl cinnamate, acetophenone, diethylphenyl succinate, catalysis, palladium, complex.
- El'man, A. R.,Boldyreva, O. V.,Slivinskii, E. V.,Loktev, S. M.
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p. 435 - 438
(2007/10/02)
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- PREPARATION AND SOME REACTIONS OF 4- AND 5-ARYL-4,5-DIHYDROPYRIDAZIN-3(2H)-ONES
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Efficient preparations of 4- and 5-phenyl-4,5-dihydropyridazin-3(2H)-ones have been developed, the main reactions of these compounds have been studied, and the synthetic routes have been used to give analogues with substituents in the phenyl rings.In the best synthesis of the 4-phenyldihyropyridazinone (72 percent overall yield) the product was obtained from phenylacetic acid by three simple stages.This approach was applied in preparations of the 2- and 4-hydroxyphenyl compounds and, in conjunction with a recent method for amine protection, the 4-aminophenyl analogue.A four stage synthesis starting from benzaldehyde gave the 5-phenyldihydropyridazinone in 47 percent overall yield; hydroxybenzaldehydes were similarly converted into 5-(allyloxyphenyl)dihydropyridazinones.Oxidation to phenylpyridazinones occured more readily with the 4- and 5-phenyldihydropyridazinones than with the 6-phenyl isomer.The 4- and 5-dihydropyridazinones were smoothly reduced to tetrahydropyridazinones by hydrogenation over platinum but were uneffected by palladium in the presence of hydrazine or cyclohexene.
- Breukelman, Stephen P.,Meakins, G. Denis
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p. 1627 - 1636
(2007/10/02)
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- Inhibition of Liver Alcohol Dehydrogenase and Ethanol Metabolism by 3-Substituted Thiolane 1-Oxides
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3-Substituted thiolane oxides (methyl, n-butyl, n-hexyl, and phenyl) were prepared and tested as inhibitors of horse, monkey, and rat liver alcohol dehydrogenases and of ethanol metabolism in rats.These compounds inhibit alcohol oxidation in an uncompetit
- Chadha, Vijay K.,Leidal, Kevin G.,Plapp, Bryce V.
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