- Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
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A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
- Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
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supporting information
p. 2074 - 2077
(2021/04/05)
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- Selective palladium-catalyzed hydroformylation of alkynes to α,β-Unsaturated Aldehydes
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Atom-efficient: A selective palladium catalyst system is used for the hydroformylation of alkynes (see picture). In this syngas reaction, various alkynes were smoothly transformed to synthetically interesting α,β-unsaturated aldehydes in good yields with high regio- and stereoselectivity. Copyright
- Fang, Xianjie,Zhang, Min,Jackstell, Ralf,Beller, Matthias
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p. 4645 - 4649
(2013/05/22)
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- Rhodium-catalyzed hydroformylation of alkynes employing a self-assembling ligand system
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Hydroformylation of alkynes is an underdeveloped atom-economic and redox-neutral method to prepare enals. Applying a new electron poor self-assembling ligand system provides the first general rhodium-catalyst for the chemo- and stereoselective hydroformylation of dialkyl- as well as diaryl-substituted alkynes to furnish enals in excellent chemo- and stereoselectivity.
- Agabekov, Vladislav,Seiche, Wolfgang,Breit, Bernhard
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p. 2418 - 2422
(2013/07/11)
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- Neutral nazarov-type cyclization catalyzed by palladium(0)
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Joining the circle: The first Pd0 catalyzed Nazarov-type cyclization of diketoesters (see scheme) proceeds in 70 % to 95 % yield under strictly neutral pH conditions. Aryl substitution of the diketoesters is not required, so the reaction shows great versatility and can also proceed with aliphatic substrates. Copyright
- Shimada, Naoyuki,Stewart, Craig,Bow, William F.,Jolit, Anais,Wong, Kahoano,Zhou, Zhe,Tius, Marcus A.
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supporting information; experimental part
p. 5727 - 5729
(2012/08/07)
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- Accessing the structural diversity of pyridone alkaloids: Concise total synthesis of rac-citridone A
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A unique route to the structural diversity of pyridone alkaloids is described based on the concept of a common synthetic strategy. Three different core structure analogues corresponding to akanthomycin, septoriamycin A, and citridone A have been prepared by using a highly selective and novel carbocyclization reaction.
- Fotiadou, Anna D.,Zografos, Alexandros L.
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p. 4592 - 4595
(2011/10/17)
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- Palladium/di-1-adamantyl-n-butylphosphine-catalyzed reductive carbonylation of aryl and vinyl halides
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A general and efficient palladium-catalyzed reductive carbonylation with low catalyst loadings (0.5 mol % Pd or below) has been developed. The formylation of aryl and heteroaryl bromides proceeds smoothly in the presence of palladium/di-1-adamantyl-n-butylphosphine at ambient pressure of synthesis gas to afford the corresponding aromatic aldehydes in good yields and excellent selectivity. In addition, vinyl halides react under similar conditions to form α,β-unsaturated aldehydes in good yield.
- Brennführer, Anne,Neumann, Helfried,Klaus, Stefan,Riermeier, Thomas,Almena, Juan,Beller, Matthias
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p. 6252 - 6258
(2008/02/04)
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- Directed regio- and stereoselective hydroformylation of mono- and 1,3-disubstituted allylic alcohols: A catalytic approach to the anti-aldol-retron
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Regioselective and diastereoselective hydroformylation of mono- and 1,3-disubstituted allylic alcohol o-DPPB esters is described. The products represent synthetically important anti-aldol retrons.
- Breit, Bernhard,Demel, Peter,Gebert, Antje
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p. 114 - 115
(2007/10/03)
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- Isomerization of epoxyalkenes to 2,5-dihydrofurans
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Disclosed are processes for the isomerization of epoxyalkenes to dihydrofurans by contacting an epoxyalkene with a catalyst comprising a quaternary organic onium iodide compounds, optionally deposited on a non-acidic support and/or in combination with a Lewis acid co-catalyst. The catalyst may comprise a supported catalyst, an unsupported catalyst or a solution of the catalytically-active components in an inert, organic solvent.
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- Structure-cytoprotective activity relationship of simple molecules containing an α,β-unsaturated carbonyl system
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In previous reports we attributed the cytoprotective activity of several sesquiterpene lactones to the presence of a nonhindered electrophilic acceptor in their structure. We suggested that the mechanism of protection would be, at least in part, mediated through a reaction between the electrophilic acceptor and the sulfhydryl-containing groups of the mucosa. We report here the gastric cytoprotective effect of simple molecules containing an α,β-unsaturated carbonyl group. In the present paper, we undertake the study of molecular accessibility and molecular shape, in addition to conformational, electronic, and steric factors. Our results helped to establish two important facts connecting chemical structure with cytoprotective effect. Firstly, an adequate molecular accessibility appears to be necessary to produce the biological response, and secondly, the α,β- unsaturated carbonyl system has to be included in a cyclic structure or, at least, in the proximity of a cyclic system.
- Rodríguez, Ana M.,Enriz, Ricardo D.,Santagata, Luis N.,Jáuregui, Esteban A.,Pestchanker, Mauricio J.,Giordano, Oscar S.
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p. 1827 - 1834
(2007/10/03)
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- Synthesis of aromatic and αβ-unsaturated aldehydes by a friedel-crafts-like electrophilic destamylation using 1,1-dichloromethyl metyhyl ether
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A mild and effective method for the preparation of a variety of aromatic (7a-m), heteroaromatic (7n-r), and α,β-unsaturated aldehydes (8a-f) is described. The reaction of trialkylaryl- (2a-o), heteroaryl- (2p-t), and 1-alkenylstannanes (4a-f and 5a-f) with dichloromethyl methyl ether (1, DCME) in the presence of aluminium trichloride followed by hydrolysis provides the corresponding aldehydes. In the case of arylstannanes the ipso-isomers are generally formed; the p-alde-hydes occur as side products. The electrophilic substitution of 1-alkenylstannanes with 1 leads to α,β-unsaturated aldehydes In an ipso- and stereospecific manner. A comparison of the leaving abilities of the stannyl and silyl groups shows a lower or even zero reactivity of the silyl-substituted compounds 8a-e towards the electrophile 1. In the silylstannylalkene 6c only the stannyl group reacts whereas the stannyl function remains unaffected in the product, aldehyde 11.
- Niestroj, Michael,Neumann, Wilhelm P.
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- Rhodium-catalyzed isomerization of 1,3-diene monoepoxides to α,β-unsaturated carbonyl compounds
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α,β-Unsaturated aldehydes and ketones are readily formed by the rhodium(I) catalyzed isomerization of 1,3-diene monoepoxides.When RhH(PPh3)4 is used as a catalyst, only (E)-α,β-unsaturated carbonyl compounds are obtained selectively.The initial 1,3-diene monoepoxides are prepared regiospecifically from α-trimethylsilyl ketones by a two step procedure, bromination and subsequent vinylative epoxidation of resulting α-bromo ketones.The overall transformation from α-trimethylsilyl ketones to α,β-enones is formally regarded as an equivalent of the regiospecific aldol condensation, and also enables the use of unsymmetrically substituted ketones as an enolate source.The significance of the isomerization as a key step in the synthesis of ar-turmerone is described.
- Sato, Susumu,Matsuda, Isamu,Izumi, Yusuke
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p. 255 - 266
(2007/10/02)
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- SYNTHESIS OF UNSATURATED HYDROXY ACIDS BY THE COBALT CARBONYL AND PHASE TRANSFER CATALYZED CARBONYLATION OF VINYL EPOXIDES
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Phase transfer catalyzed reaction of vinyl epoxides with carbon monoxide, methyl iodide, catalytic amounts of cobalt carbonyl and TDA-1, affords β-hydroxy acids.High regioselectivity was observed in some cases.
- Alper, Howard,Calet, Serge
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p. 1763 - 1766
(2007/10/02)
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- Preparation of 2-methyl-2-alkenals
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2-Methyl-2-alkenals of the formula STR1 where R1 and R2 are each hydrogen, alkyl which may additionally carry aromatic radicals, or an aromatic radical, are prepared by isomerizing a 2-alkylacrolein of the formula STR2 in the presence of hydrogen and of a catalyst which contains palladium and an oxide or salt of a rare earth metal as active components, at from 20° to 120° C. and under from 1 to 100 bar.
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- Method for the production of tiglic aldehyde
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A novel method for producing tiglic aldehyde from ethylacrolein by isomerization in the presence of a hydrogenating catalyst is disclosed. According to the invention, tiglic aldehyde can be prepared in a good yield.
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- Acyloxy-2-butenes and their preparation
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Acyloxy-2-butenes of the formula STR1 where R1, R3 and R4 are each hydrogen or alkyl of 1 to 5 carbon atoms, R2 is alkyl of 1 to 5 carbon atoms, R5 is hydrogen, alkyl of 1 to 5 carbon atoms or R6 --CO--O, and R6 and R7 are each hydrogen, alkyl of 1 to 5 carbon atoms, phenyl or cyclohexyl, the preparation of these acyloxy-2-butenes by reaction of 1-acyloxy-1,3-butadienes of the formula STR2 with carboxylic acids of the formula R7 --COOH and oxygen at 50°-180° C. in the presence of catalysts containing palladium or platinum, and the use of the compounds of the formula I, where R1, R3, R4 and R5 are hydrogen, R2 and R6 are methyl and R7 is methyl or ethyl, for the preparation of 4-acyloxytiglic aldehydes.
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- A REGIO- AND STEREO-CONTROLLED SYNTHESIS OF α,β-UNSATURATED CARBONYL COMPOUNDS
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α,β-Unsaturated carbonyl compounds and butenolides are readily prepared by the rhodium(I) catalyzed isomerization of 1,3-diene monoepoxides and α-alkylidene-γ-butyrolactones, respectively.The former transformation is formally regarded as the equivalent of a regiospecific aldol condensation of an unsymmetrical ketone.
- Sato, Susumu,Matsuda, Isamu,Izumi, Yusuke
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p. 1527 - 1530
(2007/10/02)
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- Pd(II)-CATALYZED 1,3-ALKYL MIGRATION OF 1-ALKENYL ETHYL ACETALS. PREPARATION OF α-ALKYLATED (E)-α,β-UNSATURATED CARBONYL COMPOUNDS.
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Palladium(II) complexes, such as (CH3CN)2PdCl2 and (diene)PdCl2, catalyze 1,3-alkyl migration of 1-alkenyl ethyl acetals and subsequent elimination of ethanol to give α-alkylated (E)-α,β-unsaturated carbonyl compounds in excellent yields.
- Takahashi, Mitsuru,Ishii, Norio,Suzuki, Hiroharu,Moro-Oka, Yoshihiko,Ikawa, Tsuneo
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p. 1361 - 1362
(2007/10/02)
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- Preparation of crotonaldehydes
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Crotonaldehydes are prepared by reacting 1,4-diacyloxy-but-2-enes with water in the presence of a cation exchanger. The products are starting materials for the preparation of dyes, crop protection agents, polymerization inhibitors and vulcanization accelerators.
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