- Saegusa Oxidation of Enol Ethers at Extremely Low Pd-Catalyst Loadings under Ligand-free and Aqueous Conditions: Insight into the Pd(II)/Cu(II)-Catalyst System
-
A highly efficient and practical Pd(II)/Cu(OAc)2-catalyst system of Saegusa oxidation, which converts enol ethers to the corresponding enals with a number of diverse substrates at extremely low catalyst loadings (500 mol ppm) under ligand-free and aqueous conditions, is described. Its synthetic utility was demonstrated by large-scale applications of the catalyst system to important nature molecules. This work allows Saegusa oxidation to become a highly practical approach to preparing enals and also suggests new insight into the Pd(II)/Cu(II)-catalyst system for dehydrogenation of carbonyl compounds and decreasing Pd-catalyst loadings.
- Zhu, Quan,Luo, Yunsong,Guo, Yongyan,Zhang, Yushun,Tao, Yunhai
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p. 5463 - 5476
(2021/05/05)
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- Method for preparing olefine aldehyde through catalytic oxidation of enol ether
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The invention relates to the technical field of olefine aldehyde preparation, and provides a method for preparing olefine aldehyde through catalytic oxidation of enol ether. According to the invention, a palladium catalyst, a copper salt, a solvent and enol ether are mixed and subjected to a catalytic oxidation reaction to obtain olefine aldehyde. According to the method, the copper salt is used as the oxidizing agent, the mixed solvent of water and acetonitrile is used as the reaction solvent, and the volume ratio of water to acetonitrile in the mixed solvent is controlled to be (3-7): (3-7), so that the catalytic oxidation reaction can be smoothly carried out in the mixed solvent with a specific ratio, and the generation of palladium black precipitate can be avoided. The method provided by the invention has the advantages of simple steps, low reagent cost, no need of dangerous reagents, wide substrate adaptability and small catalyst dosage. Furthermore, octadecane mercaptan is added to promote the catalytic oxidation reaction, and when the dosage of the palladium catalyst is extremely low, the olefine aldehyde yield can be greatly increased by adding octadecane mercaptan.
- -
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Paragraph 0082-0086; 0088
(2021/06/23)
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- Sulfur-controlled and rhodium-catalyzed formal (3 + 3) transannulation of thioacyl carbenes with alk-2-enals and mechanistic insights
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A rhodium-catalyzed denitrogenative formal (3 + 3) transannulation of 1,2,3-thiadiazoles with alk-2-enals is achieved, producing 2,3-dihydrothiopyran-4-ones in moderate to excellent yields. An inverse KIE of 0.49 is obtained, suggesting the reversibility of the oxidative addition of thioacyl Rh(i) carbenes to alk-2-enals. The late-stage structural modifications of steroid compounds are realized. Moreover, our studies show that thioacyl carbenes have different reactivities to those of α-oxo and α-imino carbenes, and highlight the importance of heteroatoms in deciding the reactivities of heterovinyl carbenes.
- Wu, Qiuyue,Dong, Ziyang,Xu, Jiaxi,Yang, Zhanhui
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p. 3173 - 3180
(2021/04/21)
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- Stereodefined rhodium-catalysed 1,4-H/D delivery for modular syntheses and deuterium integration
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Deuterium-incorporated compounds are of high interest owing to their importance in the pharmaceutical industry, organic synthesis and materials science. So far, the integration of deuterium into the inert, saturated magic methyl or methylene groups of covalent molecules remains challenging. Here, we present a 1,4-H delivery of allylic metallic species to provide a highly stereoselective and straightforward approach to 3-methyl-2(E)-enals or -enones from readily available 2,3-allenols and organoboronic acids. The reaction accommodates many synthetically versatile functional groups as well as multi-pharmacophores, and is not limited to the formation of 3-methyl derivatives. By applying 1,4-H or D delivery, deuterium atom(s) from differently deuterated allenols can be edited into the methyl or methylene groups of versatile organic skeletons, resulting in the efficient formation of 4-monodeuterated, 1,4- and 4,4-doubly deuterated, and 4,4,4-triply deuterated 2(E)-enals or -enones. These powerful platform molecules can provide straightforward paths to other deuterated compounds for different purposes. [Figure not available: see fulltext.].
- Cheng, Bao,Fang, Huayi,Ma, Shengming,Qian, Hui,Wang, Weiyi,Yu, Yibo,Zhang, Xue
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p. 586 - 594
(2021/07/17)
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- Deep eutectic solvent-catalyzed Meyer-Schuster rearrangement of propargylic alcohols under mild and bench reaction conditions
-
The Meyer-Schuster rearrangement of propargylic alcohols into α,β-unsaturated carbonyl compounds has been revisited by setting up an atom-economic process catalyzed by a deep eutectic solvent FeCl3·6H2O/glycerol. Isomerizations take place smoothly, at room temperature, under air and with short reaction times. The unique solubilizing properties of the eutectic mixture enabled the use of a substrate concentration up to 1.0 M with the medium being recycled up to ten runs without any loss of catalytic activity. This journal is
- Ríos-Lombardía, Nicolás,Cicco, Luciana,Yamamoto, Kota,Hernández-Fernández, José A.,Morís, Francisco,Capriati, Vito,García-álvarez, Joaquín,González-Sabín, Javier
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supporting information
p. 15165 - 15168
(2020/12/21)
-
- Heck Reactions of Acrolein or Enones and Aryl Bromides – Synthesis of 3-Aryl Propenals or Propenones and Consecutive Application in Multicomponent Pyrazole Syntheses
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3-(Hetero)aryl propenals or propenones are efficiently prepared by a Heck reaction of (hetero)aryl bromides and acrolein or vinyl ketones using Beller's CataCXium Ptb ligand under Jeffery's and Fu's conditions. The formation of these three-carbon building blocks is embedded into consecutive three- and pseudo-four-component syntheses of 3-(hetero)aryl and 3,5-diarylpyrazoles with a broad substitution pattern in moderate to excellent yield.
- Stephan, Marvin,Panther, Jesco,Wilbert, Fabio,Ozog, Pauline,Müller, Thomas J. J.
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supporting information
p. 2086 - 2092
(2020/03/23)
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- Direct Synthesis of Enones by Visible-Light-Promoted Oxygenation of Trisubstituted Olefins Using Molecular Oxygen
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A one-step synthesis of enones from olefins is described. The reaction was performed under visible-light irradiation in the presence of molecular oxygen and a photocatalyst. The reaction proceeded with various types of trisubstituted olefins to give enones in good yields with high regioselectivity. In particular, oxygen- and nitrogen-containing functional groups, heteroaromatic rings, and cyclopropanes were tolerated. Mechanistic studies and previous reports indicated that the active oxygen species generated in the reaction system is singlet oxygen.
- Harada, Shinji,Matsuda, Daiki,Morikawa, Takahiro,Nishida, Atsushi
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supporting information
p. 1372 - 1377
(2020/10/02)
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- Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
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The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
- Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
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p. 18825 - 18835
(2019/11/28)
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- Iron(III)/O2-Mediated Regioselective Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes
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A simple, efficient, and environmentally benevolent regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes mediated by iron(III) sulfate/O2 has been developed. The reaction offered good yields and excellent regioselectivity and showed good functional group tolerance (31 examples). The method is important, as few reports with limited substrate scope are available for such excellent oxidative cleavage of conjugated dienes.
- Bhowmik, Amit,Fernandes, Rodney A.
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p. 9203 - 9207
(2019/11/14)
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- Heterogeneous Acid-Catalyzed Racemization of Tertiary Alcohols
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Tertiary alcohols are important structural motifs in natural products and building blocks in organic synthesis but only few methods are known for their enantioselective preparation. Chiral resolution is one of these approaches that leaves one enantiomer (50 % of the material) unaffected. An attractive method to increase the efficiency of those resolutions is to racemize the unaffected enantiomer. In the present work, we have developed a practical racemization protocol for tertiary alcohols. Five different acidic resin materials were tested. The Dowex 50WX8 was the resin of choice since it was capable of racemizing tertiary alcohols without any byproduct formation. Suitable solvents and a biphasic system were investigated, and the optimized system was capable of racemizing differently substituted tertiary alcohols.
- G?rbe, Tamás,Lihammar, Richard,B?ckvall, Jan -E.
-
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- Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols
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An asymmetric hydrogenation of β-branched enol esters has been developed for the first time, providing a new route for the synthesis of β-chiral primary alcohols. Using a (S)-SKP-Rh complex bearing a large bite angle and enol ester substrates possessing an O-fomyl directing group, the desired products were obtained in quantitative yields and with excellent enantioselectivities.
- Liu, Chong,Yuan, Jing,Zhang, Jian,Wang, Zhihui,Zhang, Zhenfeng,Zhang, Wanbin
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supporting information
p. 108 - 111
(2018/01/17)
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- Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Scope and Mechanistic Studies
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Although iminium catalysis has become an important tool in organic chemistry, its combination with supramolecular host systems has remained largely unexplored. We report the detailed investigations into the first example of iminium catalysis inside a supramolecular host. In the case of 1,4-reductions of α,β-unsaturated aldehydes, catalytic amounts of host are able to increase the enantiomeric excess of the products formed. Several control experiments were performed and provided strong evidence that the modulation of enantiomeric excess of the reaction product indeed stems from a reaction on the inside of the capsule. The origin of the increased enantioselectivity in the capsule was investigated. Furthermore, the substrate and nucleophile scope were studied. Kinetic investigations as well as the kinetic isotope effect measured confirmed that the hydride delivery to the substrate is the rate-determining step inside the capsule. The exploration of benzothiazolidines as alternative hydride sources revealed an unexpected substitution effect of the hydride source itself. The results presented confirm that the noncovalent combination of supramolecular hosts with iminium catalysis is opening up new exciting possibilities to increase enantioselectivity in challenging reactions.
- Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
-
supporting information
p. 17500 - 17507
(2017/12/15)
-
- Synthetic approaches to mono- and bicyclic perortho-esters with a central 1,2,4-trioxane ring as the privileged lead structure in antimalarial and antitumor-active peroxides and clarification of the peroxide relevance
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The synthesis of 4-styryl-substituted 2,3,8-trioxabicyclo[3.3.1]nonanes, peroxides with the core structure of the bioactive 1,2,4-trioxane ring, was conducted by a multistep route starting from the aryl methyl ketones 1a-1c. Condensation and reduction/oxidation delivered enals 4a-4c that were coupled with ethyl acetate and reduced to the 1,3-diol substrates 6a-6c. Highly diastereoselective photooxygenation delivered the hydroperoxides 7a-7c and subsequent PPTS (pyridinium-p-toluenesulfonic acid)-catalyzed peroxyacetalization with alkyl triorthoacetates gave the cyclic peroxides 8a-8e. These compounds in general show only moderate antimalarial activities. In order to extend the repertoire of cyclic peroxide structure, we aimed for the synthesis of spiro-perorthocarbonates from orthoester condensation of β-hydroxy hydroperoxide 9 but could only realize the monocyclic perorthocarbonate 10. That the central peroxide moiety is the key structural motif in anticancer active GST (glutathione S-transferase)-inhibitors was elucidated by the synthesis of a 1,3-dioxane 15-with a similar substitution pattern as the pharmacologically active peroxide 11-via a singlet oxygen ene route from the homoallylic alcohol 12.
- Griesbeck, Axel G.,Br?utigam, Maria,Kleczka, Margarethe,Raabe, Angela
-
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- Asymmetric Traceless Petasis Borono-Mannich Reactions of Enals: Reductive Transposition of Allylic Diazenes
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The traceless Petasis borono-Mannich reaction of enals, sulfonylhydrazines, and allylboronates, catalyzed by chiral biphenols, results in an asymmetric reductive transposition of the in situ generated allylic diazene. Acyclic 1,4-diene products bearing either alkyl- or aryl-substituted benzylic stereocenters are afforded in excellent yields and enantiomeric ratios of up to 99:1. The use of crotylboronates in the reaction results in concomitant formation of two stereocenters in either a 1,4-syn or anti relationship from the corresponding E- or Z-crotylboronate used in the reaction. The use of β-monosubstituted enals in the asymmetric traceless Petasis borono-Mannich reaction of crotylboronates installs tertiary methyl-bearing stereocenters in good yields and high enantioselectivities.
- Jiang, Yao,Thomson, Regan J.,Schaus, Scott E.
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supporting information
p. 16631 - 16635
(2017/12/13)
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- Metal- and Acid-Free Methyl Triflate Catalyzed Meyer-Schuster Rearrangement
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A novel metal- and acid-free preparation of synthetically useful α,β-unsaturated carbonyl compounds from propargyl alcohols has been realized. This Meyer-Schuster rearrangement process is effectively catalyzed by methyl triflate (20 mol%) to prepare a broad scope of conjugated E -enals and E -enones generally in good to excellent yields (up to 90%). This reaction procedure operates under mild conditions (70 °C), in air, with short reaction times (1 h). Moreover, a carbocation intermediate trapped by the solvent 2,2,2-trifluoroethanol was isolated during this transformation.
- Yang, Lu,Zeng, Qingle
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p. 3149 - 3156
(2017/07/12)
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- Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Modulation of Enantiomeric Excess
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The noncovalent combination of a supramolecular host with iminium organocatalysis is described. Due to cation–π interactions the reactive iminium species is held inside the host and reacts in this confined environment. The products formed differ up to 92 % ee from the control experiments without added host. A model rationalizing the observed difference is presented.
- Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
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p. 7698 - 7701
(2016/07/07)
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- LSD1 INHIBITORS AND USES THEREOF
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Provided are novel compounds of Formula (I) and pharmaceutically acceptable salts thereof, which are useful for treating a variety of diseases, disorders or conditions, associated with LSDl. Also provided are pharmaceutical compositions comprising the novel compounds of Formula (I), pharmaceutically acceptable salts thereof, and methods for their use in treating one or more diseases, disorders or conditions, associated with LSDl.
- -
-
Paragraph 00565-00566
(2016/11/17)
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- Preparation method of alpha-beta-unsaturated carbonyl compound
-
The invention relates to a preparation method of an alpha-beta-unsaturated carbonyl compound, in particular to a method in which the alpha-beta-unsaturated carbonyl compound is prepared from substitute propargyl alcohol in a mode that positive ion modified imvite serves as a catalyst, the substitute propargyl alcohol serves as the raw material, and Meyer-Schuster rearrangement is utilized. According to the method, the substrate is wide in application range, the catalyst is cheap, easy to manufacture, stable, free of pollution to the environment and capable of being recycled, the reaction yield is high, stereoselectivity is good, and an E-type product can be obtained in a singular mode.
- -
-
Paragraph 0119; 0120; 0121; 0122; 0123; 0124; 0125; 0126
(2016/10/09)
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- Enantioselective Hydrogenation of β,β-Disubstituted Unsaturated Carboxylic Acids under Base-Free Conditions
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An additive-free enantioselective hydrogenation of β,β-disubstituted unsaturated carboxylic acids catalyzed by the Rh-(R,R)-f-spiroPhos complex has been developed. Under mild conditions, a wide scope of β,β-disubstituted unsaturated carboxylic acids were hydrogenated to the corresponding chiral carboxylic acids with excellent enantioselectivities (up to 99.3% ee). This methodology was also successfully applied to the synthesis of the pharmaceutical molecule indatraline.
- Yan, Qiaozhi,Kong, Duanyang,Zhao, Wei,Zi, Guofu,Hou, Guohua
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p. 2070 - 2077
(2016/03/15)
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- Solvent-free hydration of alkynes over Hβ zeolite
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Abstract An efficient and environmentally benign catalytic system has been successfully developed for highly Markovnikov selective hydration of various alkynes over heterogeneous catalyst (Hβ zeolite) in solvent-free conditions. The catalyst (Hβ zeolite) is commercial available, recyclable and exhibits excellent catalytic activity towards the hydration of alkynes to ketones. Moreover, the propargylic aryl carbinols undergo Meyer-Schuster rearrangement to give α,β-unsaturated carbonyl compounds in excellent yields.
- Mameda, Naresh,Peraka, Swamy,Marri, Mahender Reddy,Kodumuri, Srujana,Chevella, Durgaiah,Gutta, Naresh,Nama, Narender
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p. 213 - 216
(2015/08/24)
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- Organoselenium-catalyzed, hydroxy-controlled regio- and stereoselective amination of terminal alkenes: Efficient synthesis of 3-amino allylic alcohols
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An efficient route to prepare 3-amino allylic alcohols in excellent regio- and stereoselectivity in the presence of bases by orangoselenium catalysis has been developed. In the absence of bases α,β-unsaturated aldehydes were formed in up to 97% yield. Control experiments reveal that the hydroxy group is crucial for the direct amination.
- Deng, Zhimin,Wei, Jialiang,Liao, Lihao,Huang, Haiyan,Zhao, Xiaodan
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p. 1834 - 1837
(2015/04/27)
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- One-Pot Synthesis of β,β-Disubstituted α,β-Unsaturated Carbonyl Compounds
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TiCl4-promoted aldol reaction of ketones as aldol acceptors followed by elimination of the titanoxy group from the Ti-aldolates affords β,β-disubstituted α,β-unsaturated carbonyl compounds in a one-pot procedure. The use of additives, such as DMF, N,N,N′,N′-tetramethylethylenediamine, and pyridine, in the elimination step was found to be important.
- Sugiura, Masaharu,Ashikari, Yasuhiko,Nakajima, Makoto
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p. 8830 - 8835
(2015/09/15)
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- Silver Tetrafluoroborate-Catalyzed Oxa-Diels-Alder Reaction between Electrically Neutral Dienes and Aldehydes
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Chemoselective oxa-Diels-Alder reactions between electrically neutral 1,3-dienes and various aldehydes were achieved using the commercially available silver tetrafluoroborate (AgBF4) as catalyst. This catalytic process has high functional group tolerance. Heteroatoms at the β-position of the aryl aldehydes can greatly promote the reactivity of the substrates even with heterocyclic aldehydes that were previously believed to be unreactive for the oxa-Diels-Alder reaction. In addition, acroleins with β-heteroatom substitution are also good substrates. High chemoselectivity and regioselectivity were achieved at room temperature for the oxa-Diels-Alder reaction between acroleins and stoichiometric simple 1,3-dienes.
- Zou, Xiaodong,Yang, Lizheng,Liu, Xiangli,Sun, Hao,Lu, Hongjian
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p. 3040 - 3046
(2015/11/03)
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- Br?nsted acid-catalyzed meyer-schuster rearrangement for the synthesis of α, β -unsaturated carbonyl compounds
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An efficient and simple protocol for the Meyer-Schuster rearrangement of propargyl alcohols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of p-toluenesulfonic acid in 1,2-dichloroethane.
- Park, Jungmin,Yun, Jihee,Kim, Jaehyun,Jang, Dong-Jin,Park, Cheol Ho,Lee, Kooyeon
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p. 1924 - 1929
(2014/07/07)
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- [PF6]2 As catalyst for the meyer-schuster rearrangement of arylpropargylic alcohols under mild conditions
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The novel iridium complex [IrCpNCMe2PPh2Me][PF6]2 I efficiently catalyzed the Meyer-Schuster rearrangement of selected arylpropargylic alcohols into α,β-unsaturated aldehydes under mild conditions and without the need of a co-catalyst. A mechanism involving a hydroxy alkenylcarbene intermediate is proposed. [IrCpNCMe2PPh2Me][PF6]2 efficiently catalyzes the rearrangement of propargylic alcohols into α,β-unsaturated aldehydes under mild conditions and without the need of a co-catalyst.
- Talavera, María,Bravo, Jorge,Gonsalvi, Luca,Peruzzini, Maurizio,Zuccaccia, Cristiano,Bola?o, Sandra
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p. 6268 - 6274
(2015/02/19)
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- Ruthenium-catalyzed oxidation of allyl alcohols with intermolecular hydrogen transfer: Synthesis of α,β-unsaturated carbonyl compounds
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Ruthenium-catalyzed oxidation of multisubstituted allyl alcohols in the presence of benzaldehyde gives enals or enones in good yields. Unlike the commonly reported ruthenium-catalyzed isomerization reaction of allyl alcohols to give saturated ketones, an intermolecular rather than intramolecular hydrogen transfer is involved in this transformation. This reaction offers an efficient, mild, and high-yielding method for the preparation of substituted α,β-unsaturated compounds.
- Ren, Kai,Hu, Bei,Zhao, Mengmeng,Tu, Yahui,Xie, Xiaomin,Zhang, Zhaoguo
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p. 2170 - 2177
(2014/04/03)
-
- Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols
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Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.
- Larionov, Evgeny,Lin, Luqing,Gune, Laure,Mazet, Clment
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supporting information
p. 16882 - 16894
(2015/01/09)
-
- New Ag(I)-iminophosphorane coordination polymers as efficient catalysts precursors for the MW-assisted meyer-schuster rearrangement of propargylic alcohols in water
-
Treatment of the N-thiophosphorylated iminophosphorane ligands (PTA)=NP(=S)(OR)2 [PTA = 1,3,5-triaza-7-phosphaadamantane, 3a and 3b] and (DAPTA)=NP(=S)(OR)2 [DAPTA = 3,7-diacetyl-1,3,7-triaza-5- bicyclo[3.3.1]nonane, 4a and 4b] with an equimolecular amount of AgSbF 6 leads to high-yield formation of the new one-dimensional coordination polymers [Ag{μ2-N,S-(PTA)=NP(=S)(OR) 2}]x[SbF6]x (5a and 5b) and [Ag{μ2-O,S-(DAPTA)=NP(=S)(OR)2}]x[SbF 6]x (6a and 6b), respectively. These new (iminophosphorane)silver(I) coordination polymers are efficient catalyst precursors for the Meyer-Schuster isomerization of both terminal and internal alkynols. Reactions proceeded in water, under aerobic conditions and using microwave irradiation as heating source, to afford the corresponding α,β-unsaturated carbonyl compounds in excellent yields, without the addition of any cocatalyst. Remarkably, it should be noted that this catalytic system can be recycled up to 10 consecutive runs (1st cycle 45 min, 99%; 10th cycle 6 h, 97%). ESI-MS analysis of 5a in water has been carried out providing valuable insight into the monomeric active species responsible for catalytic activity in water.
- Garcia-Alvarez, Joaquin,Diez, Josefina,Vidal, Cristian,Vicent, Cristian
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p. 6533 - 6542
(2013/07/19)
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- Pd-arylurea complexes for the Heck arylation of crotonic and cinnamic substrates
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A catalyst consisting of the 1:2 complex of Pd(OAc)2 (1 mol %) with N-(4-carbethoxy)-phenylurea promotes the Heck arylation of a range of crotonic and cinnamic substrates, including aldehydes, ketones, esters, and nitriles, with electron-rich - but not electron-deficient - aryl iodides.
- Smith, Matthew R.,Kim, Jung Yun,Ciufolini, Marco A.
-
supporting information
p. 2042 - 2045
(2013/04/24)
-
- Selective reactivity of electron-rich aryl iodides in the Heck arylation of disubstituted alkenes catalyzed by palladium-arylurea complexes
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A catalyst consisting of 1 mol % of the 1:2 complex of Pd(OAc)2 with N-(4-carbethoxyphenyl)urea promotes the Heck arylation of 2- or 3-substituted, conjugated esters, nitriles, aldehydes, and ketones (an uncharacteristically broad range of substrates), but only with electron-rich aryl iodides (an uncharacteristically narrow range of halides).
- Smith, Matthew R.,Jang, Young Jin,Kim, Jung Yun,Ciufolini, Marco A.
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p. 10139 - 10151
(2013/11/06)
-
- Synthesis, modeling and functional activity of substituted styrene-amides as small-molecule CXCR7 agonists
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The chemokine receptor CXCR7 is an atypical G protein-coupled receptor as it preferentially signals through the β-arrestin pathway rather than through G proteins. CXCR7 is thought to be of importance in cancer and the development of CXCR7-targeting ligands is of huge importance to further elucidate the pharmacology and the therapeutic potential of CXCR7. In the present study, we synthesized 24 derivatives based on a compound scaffold patented by Chemocentryx and obtained CXCR7 ligands with pKi values ranging from 5.3 to 8.1. SAR studies were supported by computational 3D Fingerprint studies, revealing several important affinity descriptors. Two key compounds (29 and 30, VUF11207 and VUF11403) were found to be high-potency ligands that induce recruitment of β-arrestin2 and subsequent internalization of CXCR7, making them important tool compounds in future CXCR7 research.
- Wijtmans, Maikel,Maussang, David,Sirci, Francesco,Scholten, Danny J.,Canals, Meritxell,Muji?-Deli?, Azra,Chong, Milagros,Chatalic, Kristell L.S.,Custers, Hans,Janssen, Elwin,De Graaf, Chris,Smit, Martine J.,De Esch, Iwan J.P.,Leurs, Rob
-
supporting information; experimental part
p. 184 - 192
(2012/07/14)
-
- Efficient one-to-one coupling of easily available 1,3-dienes with carbon dioxide
-
An efficient one-to-one coupling reaction of atmospheric pressure carbon dioxide with 1,3-dienes is realized for the first time through PSiP-pincer type palladium-catalyzed hydrocarboxylation. The reaction is applicable to various 1,3-dienes including easily available chemical feedstock such as 1,3-butadiene and isoprene. This protocol affords a highly useful method for the synthesis of β,γ-unsaturated carboxylic acid derivatives from CO2.
- Takaya, Jun,Sasano, Kota,Iwasawa, Nobuharu
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supporting information; experimental part
p. 1698 - 1701
(2011/05/04)
-
- Iron-facilitated direct oxidative C-H transformation of allyl arenes to alkenyl aldehydes
-
A direct oxidative approach to alkenyl aldehydes from allyl arenes via allyl sp3 C-H functionalization was disclosed. An inexpensive iron catalyst was employed to facilitate this transformation. The mechanistic studies indicate that the cleavage of the allyl sp3 C-H bond is involved in the rate-determining step.
- Wang, Teng,Xiang, Shi-Kai,Qin, Chong,Ma, Jun-An,Zhang, Li-He,Jiao, Ning
-
supporting information; experimental part
p. 3208 - 3211
(2011/06/28)
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- Two-carbon homologation of aldehydes and ketones to α,β- unsaturated aldehydes
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Phosphonate reagents were developed for the two-carbon homologation of aldehydes or ketones to unbranched- or methyl-branched α,β- unsaturated aldehydes. The phosphonate reagents, diethyl methylformyl-2- phosphonate dimethylhydrazone and diethyl ethylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condensation of the reagent with the starting aldehyde, followed by removal of the dimethylhydrazone protective group with a biphasic mixture of 1 M HCl and petroleum ether. This robust two-step process worked with a variety of aldehydes and ketones. Overall isolated yields of unsaturated aldehyde products ranged from 71% to 86% after the condensation and deprotection steps.
- Petroski, Richard J.,Vermillion, Karl,Cosse, Allard A.
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experimental part
p. 5062 - 5078
(2011/08/21)
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- Iron(III) chloride-promoted isomerization of propargyl alcohols to α,β-unsaturated carbonyl compounds
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Aryl propargyl alcohols bearing a terminal alkynyl moiety can undergo a facile iron(III) chloride-promoted transformation to the corresponding α,β-unsaturated aldehyde in good yield and excellent stereoselectivity.
- El Douhaibi, Ahmad Samih,Judeh, Zaher M. A.,Basri, Hedaya,Moussa, Ziad,Messali, Mouslim,Qi, Gao
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experimental part
p. 533 - 540
(2011/04/22)
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- A simple and versatile re-catalyzed meyer-schuster rearrangement of propargylic alcohols to α,β-unsaturated carbonyl compounds
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The development of a general catalytic procedure for the rapid and efficient 1,3-rearrangement of free secondary and tertiary propargylic alcohols to the corresponding α,β-unsaturated carbonyl compounds using available [ReOCl3(OPPh3)-(SMe2)] complex, was reported. The reaction was carried out under neutral environmental conditions with no racemization of potentially enolizable stereocenters with virtually complete E stereoselectivity. The reaction under dimethoxyethane, proceeded at the lower rate than in THF, but with reduced by-products and the yield obtained were highly significant. The reaction was reported to increase constantly at the expense of the (Z)-isomer 2b, where the double bong isomerization was attributed to a catalytic effect of the rhenium complex. The resulted new version of Meyer-Schuster rearrangement will find enormous application in organic synthesis to develop one-pot multistep reaction sequences.
- Stefanoni, Massimo,Luparia, Marco,Porta, Alessio,Zanoni, Giuseppe,Vidari, Giovanni
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experimental part
p. 3940 - 3944
(2009/12/03)
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- Microwave-assisted InCl3-catalyzed Meyer-Schuster rearrangement of propargylic aryl carbinols in aqueous media: a green approach to α,β-unsaturated carbonyl compounds
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A novel, efficient, simple and environmentally benign protocol for the Meyer-Schuster isomerization of propargylic aryl carbinols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of InCl3, pure water as the solvent, and microwave irradiation as the heating source.
- Cadierno, Victorio,Francos, Javier,Gimeno, José
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experimental part
p. 4773 - 4776
(2011/03/19)
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- Stereochemical course of baker's yeast mediated reduction of the tri- and tetrasubstituted double bonds of substituted cinnamaldehydes
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A comprehensive study of the stereochemical course of baker's yeast mediated reduction of substituted cinnamaldehydes is reported. Hydride addition to the β position of β-methylcinnamaldehydes preferentially afforded isomers of (3S)-3-phenylbutan-1-ol. The reduction of (E)-2,3-dimethyl- cinnamaldehyde (15) produced a mixture of (2S,3S)- and (2R,3S)-2-methyl-3- phenylbutan-1-ol (13 and 14), respectively, with 93 % ee. Conversely (Z)-2,3-dimethylcinnamal-dehyde (16) afforded, a mixture of 13 and 14 with 33 % ee. Accordingly, the reduction of trisubstituted β-methylcinnam-aldehydes 34 and 35 proceeded with the same stereochemical preference and with higher enantioselectivity to give (S) 3-phenylbutan-1-ol (37). In addition, deuterium, incorporation and 2H NMR studies demonstrated that the addition of the second hydrogen atom to the a position proceeded with very low stereochemical control and the overall process is formally a mixture of cis/trans hydrogen addition to the double bond. Alternatively, α-methylcinnamaldehyde is reduced to (S)-2-methyl-3-phenylpropan-1-ol (24) with preferential addition of the hydride to the opposite β face with good stereochemical control of the irons addition of hydrogen to the double bond. Wiley-VCH Verlag GmbH & Co. KGaA.
- Fronza, Giovanni,Fuganti, Claudio,Serra, Stefano
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experimental part
p. 6160 - 6171
(2010/03/24)
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- Alkyne-enol ether cross-metathesis in the presence of CuSO4: Direct formation of 3-substituted crotonaldehydes in aqueous medium
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An efficient synthesis of 3-substituted crotonaldehydes via alkyne-enol ether cross-metathesis in the presence of CuSO4 and in aqueous medium was developed. Crotonaldehydes were obtained in good yields from terminal aryl-alkynes as well as from
- Castagnolo, Daniele,Botta, Lorenzo,Botta, Maurizio
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supporting information; experimental part
p. 3172 - 3174
(2009/08/07)
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- Simple one-pot conversion of aldehydes and ketones to enals
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A simple and efficient method to convert aldehydes into α,β-unsaturated aldehydes with a two-carbon homologation is presented. Hydroboration of ethoxy acetylene with BH3·SMe 2 generates tris(ethoxyvinyl) borane. Transmetalation with
- Valenta, Petr,Drucker, Natalie A.,Bode, Jeffrey W.,Walsh, Patrick J.
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supporting information; experimental part
p. 2117 - 2119
(2009/10/18)
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- Competitive inhibition of aristolochene synthase by phenyl-substituted farnesyl diphosphates: Evidence of active site plasticity
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Analogues of farnesyl diphosphate (FPP, 1) containing phenyl substituents in place of methyl groups have been prepared in syntheses that feature use of a Suzuki-Miyaura reaction as a key step. These analogues were found not to act as substrates of the sesquiterpene cyclase aristolochene synthase from Penicillium roqueforti (AS). However, they were potent competitive inhibitors of AS with KI-values ranging from 0.8 to 1.2 M. These results indicate that the diphosphate group contributes the largest part to the binding of the substrate to AS and that the active sites of terpene synthases are sufficiently flexible to accommodate even substrate analogues with large substituents suggesting a potential way for the generation of non-natural terpenoids. Molecular mechanics simulations of the enzyme bound inhibitors suggested that small changes in orientations of active site residues and subtle alterations of the conformation of the backbones of the inhibitors are sufficient to accommodate the phenyl-farnesyl-diphosphates. This journal is The Royal Society of Chemistry.
- Miller, David J.,Yu, Fanglei,Young, Neil J.,Allemann, Rudolf K.
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p. 3287 - 3298
(2008/09/20)
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- Asymmetric allylboration of α,β-enals as a surrogate for the enantioselective synthesis of allylic amines and α-amino acids
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(Chemical Equation Presented) Optically pure allylic amines have been synthesized from α,β-unsaturated aldehydes via allylboration with (-)-B-allyldiisopinocampheylborane, followed by Overman rearrangement. By incorporating crotyl and alkoxyallylboration, functionalization at δ-position was readily accomplished. By applying this methodology, the synthesis of several chiral α-amino acids has been achieved.
- Ramachandran, P. Veeraraghavan,Burghardt, Thomas E.,Reddy, M. Venkat Ram
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p. 2329 - 2331
(2007/10/03)
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- An investigation of the behaviour of α,β-unsaturated sulfoxides in the presence of trimethylsilyl iodide
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A mild, efficient and seemingly general method for converting α,β-unsaturated sulfoxides into carbonyl compounds by means of trimethylsilyl iodide (TMSI) is described. Experiments on different substrates and trimethylsilyl halides lead to the conclusion that the oxidation state of the sulfur atom, on one hand, and halogen kind in TMSX on the other, assume a determining role in the progression of the reaction. The ease of experimental procedure, the possibility of 1H NMR monitoring, and good yields of final products constitute advantages of the TMSI-promoted conversion of α,β-unsaturated sulfoxides into carbonyl compounds.
- Aversa, Maria C.,Barattucci, Anna,Bonaccorsi, Paola,Giannetto, Placido
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p. 10145 - 10150
(2007/10/03)
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- Stereocontrolled IMDA reaction of styrene derivatives. A way to enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines
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IMDA reactions on chiral perhydro-1,3-benzoxazines, derived from (-)-8-amino menthol, bearing a styrene substituent at C-2 acting as diene and an acryl amide acting as dienophile occur with high stereoselection and excellent chemical yields. After elimination of the chiral appendage, enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines are prepared in this way. The effect of the substituents at both diene and dienophile are studied, showing that a methyl group at C-1 in the diene inhibited the reaction, while the ene adduct, instead of the IMDA product, was obtained when a methyl group was at C-2.
- Pedrosa, Rafael,Andres, Celia,Nieto, Javier
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p. 782 - 789
(2007/10/03)
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- Nickel-catalyzed preparation of stereodefined allylic alcohols using silicon-tethered ynals
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The nickel-catalyzed cyclization of silicon-tethered ynals is reported. The silicon heterocycles obtained may be converted into allylic alcohols that possess a stereodefined alkene unit via a cleavage process that involves stereospecific protodesilylation of the vinyl silane functionality.
- Lozanov, Mario,Montgomery, John
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p. 3259 - 3261
(2007/10/03)
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- Efficient ruthenium-catalysed synthesis of 3-hydroxy-1-propen-1-yl benzoates: En route to an improved isomerization of 2-propyn-1-ols into α,β-unsaturated aldehydes
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A two-step ruthenium(II) and acid-catalysed one-pot selective transformation of 2-propyn-1-ols into α,β-unsaturated aldehydes has been developed. The complex [(dppe)Ru(η3CH2C(Me)CH2)2] (dppe = Ph2PCH2CH2PPh2) is an efficient precatalyst for the anti-Markovnikov addition of benzoic acid to 2-propyn-1-ols with the formation of 3-hydroxy-1- propen-1-yl benzoates in good yields. The latter readily undergo rapid transformation into α,β-unsaturated aldehydes on treatment with a catalytic amount of an acid such as PTSA or HBF4 at room temperature.
- Picquet, Michel,Fernandez, Aranzazu,Bruneau, Christian,Dixneuf, Pierre H.
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p. 2361 - 2366
(2007/10/03)
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- Applications of High-Temperature Aqueous Media for Synthetic Organic Reactions
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Preparative organic synthesis was investigated in aqueous media at temperatures up to 300°C. Experiments were conducted with a recently disclosed pressurized microwave batch reactor (MBR) or in conventionally heated autoclaves. Thirty-six examples are presented. Among these, methods were developed for a Fischer synthesis, an intramolecular aldol condensation that was scaled up, decarboxylation of indole-2-carboxylic acid, Rupe rearrangement of 1-ethynyl-l-cyclohexanol, isomerization of carvone to carvacrol, and conversion of phenylacetylene to acetophenone. The applicability of high-temperature water was also demonstrated for biomimetic processes important in food, flavor, and aroma chemistry and for tandem reactions such as formation of 2-methyl-2,3- dihydrobenzofuran from allyl phenyl ether. When addition of acid or base was necessary, less agent was usually required for high-temperature processes than for those at and below boiling, and the reactions often proceeded more selectively. In some instances the requirement was orders of magnitude lower, with obvious consequences for safe, economic processing and for lowering costs of effluent disposal. The diversity of reactions indicates that high-temperature aqueous media could play an increasingly important role in the development of new preparative processes.
- An, Jingyi,Bagnell, Laurence,Cablewski, Teresa,Strauss, Christopher R.,Trainor, Robert W.
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p. 2505 - 2511
(2007/10/03)
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- Selective isomerisation of prop-2-yn-1-ols into α,β-unsaturated aldehydes catalysed by Ru[η3-CH2C(Me)CH2]2(Ph 2PCH2CH2PPh2)
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The complex Ru[η3-CH2C(Me)CH2]2(Ph 2PCH2CH2PPh2) is an efficient catalyst precursor for the isomerisation of prop-2-yn-1-ols into conjugated enals under mild conditions in the presence of benzoic acid via (Z)-3-hydroxyprop-1-en-1-yl benzoates.
- Picquet, Michel,Bruneau, Christian,Dixneuf, Pierre H.
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p. 1201 - 1202
(2007/10/03)
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