- 1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
-
Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
-
supporting information
(2019/08/01)
-
- Synthesis of α,β-unsaturated aldehydes based on a one-pot phase-switch dehydrogenative cross-coupling of primary alcohols
-
An efficient one-pot ruthenium-catalyzed hydrogen-transfer strategy for a direct access to α,β-unsaturated aldehydes has been developed. The employment of enolates prepared in situ from alcohols avoided handling unstable aldehydes and provided a very appealing route to different cinnamaldehydes substituted in position 2. A silica-grafted amine was used as phase-switch tag leading to a selective one-pot process in favor of cross-dehydrogenative coupling products.
- Mura, Manuel G.,De Luca, Lidia,Taddei, Maurizio,Williams, Jonathan M. J.,Porcheddu, Andrea
-
supporting information
p. 2586 - 2589
(2014/06/09)
-
- Aldol condensation of benzaldehyde with heptanal to jasminaldehyde over novel Mg-Al mixed oxide on hexagonal mesoporous silica
-
A novel calcined hydrotalcite supported on hexagonal mesoporous silica (CHT/HMS) was synthesized and characterized by XRD, TG-DTA, pore size analysis, SEM-EDAX, and TEM. It possesses high thermal stability, high adsorption capacity and large surface area. 20% (w/w) CHT/HMS was highly active and selective in aldol-condensation of benzaldehyde with heptanal. A kinetic model was developed and validated against experimental data. Jasminaldehyde selectivity of 86% was obtained with heptanal to benzaldehyde mole ratio of 1:5 at 150 °C by using 20% (w/w) CHT/HMS. The results are explained on the basis of the bi-functional character of CHT/HMS, where the role of the weak acid sites is the activation of benzaldehyde by protonation of the carbonyl group which favors the attack of the enolate heptanal intermediate generated on basic sites. The catalyst is stable and reusable.
- Yadav, Ganapati D.,Aduri, Pavankumar
-
experimental part
p. 142 - 154
(2012/03/10)
-
- A selective solvent-free self-condensation of carbonyl compounds utilizing microwave irradiation
-
An environmentally benign microwave-assisted solvent-free self-condensation of carbonyl compounds was developed using catalytic amounts of triethylamine and lithium perchlorate. Changing the amount of lithium perchlorate helps in controlling the ratio of the single-condensation and double-condensation products. The effect of other additives and microwave activation was also investigated. The optimized conditions were then applied to various cyclic/acyclic ketones and aldehydes, with selectivity observed in many cases.
- Sharma, Lalit Kumar,Kim, Kyung Bo,Elliott, Gregory I.
-
supporting information; experimental part
p. 1546 - 1549
(2011/07/31)
-
- A green method for the self-aldol condensation of aldehydes using lysine
-
A self-condensation of aldehydes has been conveniently accomplished by the catalytic action of lysine in water or a solvent-free system under specific emulsion conditions to give α-branched α,β-unsaturated aldehydes in good yields.
- Watanabe, Yutaka,Sawada, Kazue,Hayashi, Minoru
-
experimental part
p. 384 - 386
(2010/08/04)
-
- Inorganic ammonium salts as catalysts for direct aldol reactions in the presence of water
-
Inorganic ammonium salts catalyze the direct aldol reaction between unmodified ketones and aldehydes to furnish the corresponding β-hydroxy ketones in aqueous media. The reactions are highly chemoselective and operationally simple.
- Dziedzic, Pawel,Bartoszewicz, Agnieszka,Córdova, Armando
-
supporting information; experimental part
p. 7242 - 7245
(2010/02/28)
-
- Palladium-nanoparticle-catalysed ullmann reactions in ionic liquids with aldehydes as the reductants: Scope and mechanism
-
An efficient Ullmann-type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd-catalysed dehydrogenation of carbonyl compounds.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Cotugno, Pietro
-
experimental part
p. 1272 - 1279
(2009/08/14)
-
- Rhodium(I) complexes with 1′-(diphenylphosphino)ferrocenecarboxylic acid as active and recyclable catalysts for 1-hexene hydroformylation
-
The rhodium complex trans-[Rh(CO)(Hdpf-κP)(dpf-κ2O, P)] (1), (Hdpf = 1′-(diphenylphosphino)ferrocenecarboxylic acid) was used as an efficient and recyclable catalyst for 1-hexene hydroformylation producing ca. 80% of aldehydes at 10 atm CO/Hsu
- Trzeciak, Anna M.,?těpni?ka, Petr,Mieczyńska, Ewa,Zió?kowski, Józef J.
-
p. 3260 - 3267
(2007/10/03)
-
- Synthesis and sensorial properties of 2-alkylalk-2-enals and 3-(acetylthio)-2-alkyl alkanals
-
Parallel synthesis was applied to prepare a series of 3-(acetylthio)-2-alkyl alkanals by Michael addition of thioacetic acid under alkaline conditions to α,β-unsaturated 2-alkyl-substituted aldehydes, which were obtained by aldol condensation of the corresponding primary aldehydes as starting materials. The target compounds were characterized in terms of GC, MS, and NMR data. The sensory properties of the odorants, such as odor quality and odor detection threshold value, were determined with a trained panel. Structure-activity relationships are discussed, suggesting that the 1,3-oxygen-sulfur functionality, required for the "olfactophore" of tropical/vegetable notes, can further be extended to the acetylthio derivatives.
- Robert, Fabien,Heritier, Julien,Quiquerez, Joelle,Simian, Herve,Blank, Imre
-
p. 3525 - 3529
(2007/10/03)
-
- Aldol Condensations on Solid Catalysts: A Cooperative Effect between Weak Acid and Base Sites
-
An amorphous aluminophosphate (ALPO) catalyst containing weak acid and base centers can carry out the aldol condensation of heptanal with benzaldehyde at much higher rates and selectivities than conventional solid acid (amorphous or crystalline aluminosil
- Climent,Corma,Fornes,Guil-Lopez,Iborra
-
p. 1090 - 1096
(2007/10/03)
-
- Acid-base bifunctional catalysts for the preparation of fine chemicals: Synthesis of jasminaldehyde
-
Jasminaldehyde was prepared by condensation between benzaldehyde and heptanal. Large-pore acid zeolites (HY and Beta), mesoporous aluminosilicate (Al MCM-41), and amorphous aluminophospates (ALPO) were used as catalysts. The results indicated that zeolites showed lower activity and selectivity than mesoporous aluminosilicate (Al MCM-41). These results were attributed to the confinement effects of the reactants and products inside of the voids of the microporous materials, which lead to the preferential formation of the heptanal self-condensation product, as well as to a fast deactivation of the catalyst. However, the amorphous aluminophosphate (ALPO) which possesses weaker acid sites than zeolites and MCM-41, but combines acidic and basic sites, showed the maximum activity and selectivity to jasminaldehyde. This finding was explained on the basis of the acid-base bifunctional character of the ALPO catalyst. The role of the weak acid sites is to activate benzaldehyde by protonation of the carbonyl group, favoring then the attack of the enolate heptanal intermediate generated on the relatively weak basic sites of ALPO.
- Climent,Corma,Garcia,Guil-Lopez,Iborra,Fornes
-
p. 385 - 393
(2007/10/03)
-
- Pyrrolidine-catalyzed homo-aidol condensation reactions of aldehydes
-
The first example of synthetically useful pyrrolidine-catalyzed homocoupling reaction of aliphatic aldehydes accelerated by benzoic acid is presented together with a plausible reaction mechanism. Thieme Stuttgart.
- Ishikawa, Teruhiko,Uedo, Eiji,Okada, Siho,Saito, Seiki
-
p. 450 - 452
(2007/10/03)
-
- Polyoxometalates as reduction catalysts: Deoxygenation and hydrogenation of carbonyl compounds
-
Excellent deoxygenation of ketones and aldehydes is achieved with Keggin-type polyoxometalates in the presence of hydrogen (see Equation (1) for an example). The mixed addenda phosphovanadomolybdate [PV2Mo10O4]5- was found to be the best catalyst. X-ray diffraction and IR studies suggest that the polyoxometalates are structurally stable under the strongly reducing conditions.
- Kogan, Vladimir,Aizenshtat, Zeev,Neumann, Ronny
-
p. 3331 - 3334
(2007/10/03)
-
- Use of mesoporous MCM-41 aluminosilicates as catalysts in the preparation of fine chemicals: A new route for the preparation of jasminaldehyde with high selectivity
-
α-n-Amylcinnamaldehyde (Jasminaldehyde) has been prepared with high selectivity and using low ratios of benzaldehyde/heptanal by means of mesoporous molecular sieve catalysts and a process which involves the acetalization of heptanal with methanol, followed, in the same pot, by a slow hydrolysis of dimethylacetal and the aldolic condensation of the two aldehydes as the final step. A large pore zeolite (Beta) as well as mesoporous silica-aluminas with regular pore sizes such as MCM-41 and SAM have been used as catalysts. The results indicate that mesoporous silica-aluminas with a very narrow range of pore diameter such as MCM-41 are the most adequate catalysts to produce in one pot the three consecutive reactions, avoiding in a very large extent the self-condensation of heptanal and undesired consecutive reactions. This new route allows us to achieve Jasminaldehyde with high selectivity and with a relative high global reaction rates. The influence of the concentration of acid sites on MCM-41, reaction temperature, and molar ratio of the reactants have been also studied.
- Climent,Corma,Guil-Lopez,Iborra,Primo
-
-
- Synthesis of jasminaldehyde by solid-liquid phase transfer catalysis without solvent, under microwave irradiation
-
α-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82% yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W.
- Abenhaim,Ngoc Son,Loupy,Ba Hiep
-
p. 1199 - 1205
(2007/10/02)
-
- Synthesis of α,β-Unsaturated Carbonyl Compounds by Titanium Tetraalkoxide-Induced Aldol Condensation under Neutral Conditions
-
Aldehydes and ketones, when treated with titanium tetraalkoxides in a hydrocarbon solvent at 20-140 deg C, undergo aldol condensation to give α,β-unsaturated carbonyl compounds.To avoid Meerwein-Ponndorf-Verley type reduction of the carbonyl compounds, titanium tetra-tert-butoxide is used, if the reaction is carried out at higher temperatures.In all other cases titanium tetraisopropoxide can be successfully employed.The outlined procedure offers the possibility of performing aldol condensations under neutral conditions.
- Mahrwald, Rainer,Schick, Hans
-
p. 592 - 595
(2007/10/02)
-
- The Dehydrogenation of Alcohols with Tris-(o-methoxyphenyl)carbenium Chloride.
-
Heptan-1-ol, benzyl alcohol, and cyclohexanol are dehydrogenated by tris-(o-methoxyphenyl)carbenium chloride (2) in dichloromethane solution under mild conditions without concomitant formation of quinonoid adducts (6) (through the intermediacy of which part of the alcohols would be trapped and escape oxidation).The yields of the resulting benzaldehyde and cyclohexanone are good to excellent; but the yield of the saturated aldehyde heptanal is at best moderate.In contrast to benzaldehyde and cyclohexanone, heptanal is sensitive to the reagent (2) under the prevailing conditions, and is further transformed into mixtures of heptanoic acid, heptyl heptanoate and 2-pentylnon-2-enal.
- Huszthy, Peter,Lempert, Karoly,Simig, Gyula,Tamas, Jozsef,Hegedus-Vajda, Judit,Almasy, Attila
-
p. 2524 - 2540
(2007/10/02)
-
- Alkylation of Lithium Trialkylalkynylborates with Benzo-1,3-dithiolium Fluoroborate
-
Lithium trialkylalkynylborates react in a stereoselective fashion with benzo-1,3-dithiolium fluoroborate to give vinylboranes which on oxidation yield protected 3-oxo-aldehydes and on hydrolysis give protected αβ-unsaturated aldehydes; the hydrolysis is highly selective giving rise eventually to stereospecifically defined αβ-unsaturated aldehydes by a novel process.
- Pelter, Andrew,Rupani, Pushpa,Stewart, Peter
-
p. 164 - 165
(2007/10/02)
-