Synthesis Of Aldehydes Research Articles

Spinel Structured Copper Ferrite Nano Catalyst with Magnetic Recyclability for Oxidative Decarboxylation of Phenyl Acetic Acids

A simple, efficient and environmentally benign method has been discussed for the synthesis of aldehydes and ketones by the oxidative decarboxylation of phenylacetic acid under ligand free condition using simple, efficient, preparatively easy, magnetically recoverable and low cost spinel CuFe2O4 nanoparticles. The catalyst was characterised using powder-XRD, FTIR, FE-SEM, EDX, VSM and HRTEM. The recyclability was examined and the results showed that the catalyst remained almost equally active up to five consecutive cycles. Spinel Structured Copper Ferrite is a very efficient nano catalyst for Oxidative decarboxylation of Phenyl acetic acids and can be reused up to five cycles without significant loss in catalytic activity.

Reaction Mechanism of the Isomerization of Monoterpene Epoxides with Fe3+ as Active Catalytic Specie: A Computational Approach.

The reaction mechanism of the isomerization of α and β-pinene epoxides with Fe species as catalysts was studied with density functional theory (DFT) calculations and an experimental methodology. β-pinene epoxide can be isomerized into myrtanal and myrtenol in four steps, while in the case of perillyl alcohol, two additional steps are necessary. On the other hand, high selectivity to myrtanal obtained experimentally can be explained by the number of steps and the kind of the hydrogen transference that is easier for this compound in comparison with myrtenol and perillyl alcohol. A thermodynamic analysis showed that transformation into myrtenol, myrtanal, and perillyl alcohol is spontaneous but transformation into myrtanal is the most favorable. In the case of α-pinene epoxide rearrangement, a mechanistic study was carried out toward the optimization of the possible intermediates. Synthesis of campholenic aldehyde and carveol from α-pinene epoxide was carried out through three steps after the coordination of oxygen to iron, showing that in contrast to carveol formation, campholenic aldehyde synthesis is spontaneous. Analysis of ∇2ρ, the total energy density (H = V + G), and the |V|/G ratio evaluated at the bond critical point of the Fe-O bond showed for both epoxides that such interaction is closed shell instead of covalent. Apparently, α-pinene epoxide can be isomerized faster that β-pinene epoxide with Fe3+, which is in agreement with previous experimental results. This is the first report where a reaction mechanism of isomerization of monoterpenes epoxides is studied based on very detailed experimental and computational methodologies.

Aromatic Aldehydes Production by Oxidative Degradation of Solid Residue Derived from Pine Waste Hydrolysis Coupling Acetylation

Xylose and cellulose acetate were prepared by hydrolysis and acetylation of hemicellulose and cellulose in landscaping biomass waste (pine) by dilute acid hydrolysis and acetylation, respectively. The obtained solid residue was rich in lignin that mainly contains three phenylpropane structural units and can be used to prepare aromatic chemicals under hydrothermal conditions. In this work, the synthesis of high value-added aromatic aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde) from the solid residue (rich in lignin) by mild catalytic oxidation was studied. The oxidation degradation of the solid residue in NaOH solution to produce aromatic aldehydes was investigated by single factor experiment. The optimum reaction conditions were obtained as follows: 175 ℃, 90 min, 3.0 g solid residue, 100.0 ml NaOH solution (concentration of 2.0 mol/L), and oxygen pressure of 1.5 MPa. Under these conditions, the total yield of aromatic aldehydes from pine branch residue was 23.8 wt%.

“Enal to Aryl Aldehyde” Benzannulation Strategy for the Synthesis of Biaryl Aldehydes

“Enal to Aryl Aldehyde” Benzannulation Strategy for the Synthesis of Biaryl Aldehydes

Continuous flow synthesis of aryl aldehydes by Pd-catalyzed formylation of phenol-derived aryl fluorosulfonates using syngas.

This communication describes the palladium-catalyzed reductive carbonylation of aryl fluorosulfonates (ArOSO2F) using syngas as an inexpensive and sustainable source of carbon monoxide and hydrogen. The conversion of phenols to aryl fluorosulfonates can be conveniently achieved by employing the inexpensive commodity chemical sulfuryl fluoride (SO2F2) and base. The developed continuous flow formylation protocol requires relatively low loadings for palladium acetate (1.25 mol%) and ligand (2.5 mol%). Good to excellent yields of aryl aldehydes were obtained within 45 min for substrates containing electron withdrawing substituents, and 2 h for substrates containing electron donating substituents. The optimal reaction conditions were identified as 120 °C temperature and 20 bar pressure in dimethyl sulfoxide (DMSO) as solvent. DMSO was crucial in suppressing Pd black formation and enhancing reaction rate and selectivity.

Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters

Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane.

Biaryl and atropisomeric biaryl aldehyde synthesis by one-step, metal-free benzannulation of aryl enals and propiolates

The metal-free benzannulation reactions of alkyl propiolates and aryl enals have been developed for biaryl and atropisomeric biaryl aldehyde synthesis.

Visible-light-promoted oxidative decarboxylation of arylacetic acids in air: Metal-free synthesis of aldehydes and ketones at room temperature

A metal-free photocatalytic oxidative decarboxylation reaction at room temperature was developed for the synthesis of aromatic aldehydes and ketones from the corresponding arylacetic acids. The reaction was realized under blue-light irradiation by adding 1 mol% of 4CzIPN as photocatalyst and air as oxidant. This reaction represents a novel decarboxylation of a sp3-hybridized carboxylic acids without traditional heating, additional oxidants, and metal reagents under mild conditions.

Amine-Catalyzed Enantioselective Synthesis of Cyclic β-Amino Aldehydes

Amine-Catalyzed Enantioselective Synthesis of Cyclic β-Amino Aldehydes

Synthesis of Phthalic Aldehyde and Its Diacetals

Acyclic phthalaldehyde diacetal without cyclic 1,3-dihydro-1,3-dimethoxybenzo[c]furan impurity has been obtained via the reaction of 1,2-bis(dibromomethyl)benzene with trimethyl orthoformate (1:6) at 90°C in the presence of 10 mol% of ZnCl2. Hydrolysis of phthalaldehyde diacetal has led to the formation of phthalaldehyde without HBr evolution. The reaction of phthalaldehyde with trimethyl orthoformate in the presence of trifluoroacetic acid has proceeded abnormally, with the formation of the cyclic diacetal. The acyclic diacetal has been phosphorylated by chlorophosphines and the action of PCl3 and a P(III) acid ester in sequence.

Synthesis, characterization, and biological evaluation of indole aldehydes containing N-benzyl moiety

The present study describes the synthesis, characterization and biological evaluation of N-benzyl indole aldehydes. The biological activities of the newly synthesized compounds were examined by investigating their antioxidant and anti-inflammatory activities. The potential of these compounds as an antioxidant was determined by 2,2-diphenylpicrylhydrazyl, Nitric oxide, Superoxide, peroxide radical scavenging methods. We found that aldehydes 4a, 4b, 4c, and 4e and shows promising in vitro DPPH scavenging antioxidant activity while aldehyde 4b and 4e show good in vitro anti-inflammatory activity.

A functionally-distinct carboxylic acid reductase PcCAR4 unearthed from a repertoire of type IV CARs in the white-rot fungus Pycnoporus cinnabarinus

Carboxylic acid reductases (CARs) are attracting burgeoning attention as biocatalysts for organic synthesis of aldehydes and their follow-up products from economic carboxylic acid precursors. The CAR enzyme class as a whole, however, is still poorly understood. To date, relatively few CAR sequences have been reported, especially from fungal sources. Here, we sought to increase the diversity of the CAR enzyme class. Six new CAR sequences from the white-rot fungus Pycnoporus cinnabarinus were identified from genome-wide mining. Genome and gene clustering analysis suggests that these PcCAR enzymes play different natural roles in Basidiomycete systems, compared to their type II Ascomycete counterparts. The cDNA sequences of all six Pccar genes were deduced and analysis of their corresponding amino acid sequence showed that they encode for proteins of similar properties that possess a conserved modular functional tri-domain arrangement. Phylogenetic analyses showed that all PcCAR enzymes cluster together with the other type IV CARs. One candidate, PcCAR4, was cloned and over-expressed recombinantly in Escherichia coli. Subsequent biotransformation-based screening with a panel of structurally-diverse carboxylic acid substrates suggest that PcCAR4 possessed a more pronounced substrate specificity compared to previously reported CARs, preferring to reduce sterically-rigid carboxylic acids such as benzoic acid. These findings thus present a new functionally-distinct member of the CAR enzyme class.

Synthesis of the Antimalarial Peptide Aldehyde, a Precursor of Kozupeptin A, Utilizing a Designed Hydrophobic Anchor Molecule.

This Letter describes an efficient method of synthesizing highly bioactive peptide aldehydes without any concern about epimerization by liquid-phase peptide synthesis through the use of newly designed hydrophobic anchor molecules. Peptide elongation reactions effectively proceeded in less polar solvents, and direct crystallization by the addition of polar solvents enabled easy purification. This method also represents a new concept for the efficient synthesis of peptide derivatives. The development of new antimalarial drug candidates will be accelerated using this methodology.

Transaminase-Catalyzed Continuous Synthesis of Biogenic Aldehydes.

The physiological role of biogenic aldehydes, such as 3,4-dihydroxyphenylacetaldehyde (DOPAL), has been associated with cardiovascular and neurodegenerative disorders. The availability of these substrates is limited and robust synthetic methodologies would greatly facilitate further biological studies. Herein, a transaminase-mediated single-step process in continuous mode, which leads to excellent product yields (90-95 %), is reported. Coimmobilization of the pyridoxal phosphate (PLP) cofactor eliminated the need for exogenous addition of this reagent without affecting the longevity of the system, delivering a truly self-sufficient process.

Recent developments and comparison of transformation strategies for organic halides to aldehydes and ketones.

Aldehydes and ketones are parts of millions of compounds and are important classes of chemicals which serve as important precursors for the synthesis of library of compounds. For the synthesis of aldehydes and ketones, one impressive approach to date, because of its excellent selectivity, high yield and stability toward over-reduction and over-oxidation, is the oxidation of organic halides (viz. aliphatic and benzyl halides). The current review covers the conventional and eco-friendly transformational approaches, from 2000 to date, toward synthesis of aldehydes and ketones from organic halides, including mechanistic studies, comparison of different transformational strategies and discussion on scope and cons and pros of each transformational approach. The review would be beneficial to get knowledge about recent synthesis techniques, select finest synthetic approach, develop further new transformational methodologies and improve current transformational approaches.

Mechanistic Insight into Photoelectrochemical Conversion of Alkyl Monohalides to Aldehydes

Aldehydes are important starting materials for a variety of chemical processes such as the synthesis of food preservatives. For example, certain aldehydes may be used for improving sensory quality and shelf-life of milk.1 Synthesis of aldehydes from alkyl monohalides involves a multi-stage reaction which various reagents are needed for each step of the conversion.2 Previous works from our laboratory showed that simultaneous introduction of UV radiation and oxygen during electrolysis of an alkyl monohalide with electrogenerated nickel(I) salen affords the corresponding aldehyde or ketone with relatively high yield (Figure 1). 3,4 The purpose of the present work is to elucidate the mechanism for the above-mentioned conversion. For this purpose, a solution of 1-bromooctane (5 mM) and nickel(II) salen (5 mM) was electrolyzed at –1.0 V in DMF–water containing TMABF4 (0.10 M). At the end of the electrolysis, modified nickel(II) salen was separated from the electrolysis mixture with application of normal phase flash chromatography. Modified nickel(II) salen was dissolved in DMF–water containing TMABF4 (0.10 M) and exposed to UV radiation (440 nm); the product of the photoreaction was identified as octanal. In respect, we believe the reaction passes through a series of the intermediates are proposed in Figure 2. This reaction features a single-step and efficient method for transforming alkyl monohalides into the desired aldehydes. References Kelly, P. Woonton, B. W. Smithers, G. W. Woodhead. Woodhead Publishing Ltd. 2009. 170.Hendrickson, J. B., Sternbach, D. D. J. Org. Chem. 1975, 40, 3450.Vanalabhpatana, P.; Peters, D. G. Tetrahedron Lett. 2003, 44, 3245.Vanalabhpatana, P.; Peters, D. G. J. Electroanal. Chem. 2006, 593, 34. Figure 1

Outstanding response of carbon nitride photocatalysts for selective synthesis of aldehydes under UV-LED irradiation

The photocatalytic conversion of alcohols into the corresponding aldehydes constitutes an important reaction in organic synthesis. Optical semiconductors based on carbon nitride were prepared by thermal condensation of dicyandiamide followed by a thermal post-treatment (gCN-T) and further sonication (gCN-TS). The efficiency of these materials was evaluated on the selective conversion of different aromatic alcohols to the corresponding aldehydes, namely anisaldehyde, benzaldehyde, tolualdehyde, piperonal and vanillin. The best performance of gCN-T (1 g L−1) was found for the conversion of anisyl alcohol to anisaldehyde (>99% conversion and selectivity in 45 min of UV-LED irradiation). The alcohol conversion and yield for aldehyde formation was related with the number, electronic nature and position of the functional groups in the aromatic ring. The use of gCN-TS, constituted by carbon nitride nanosheets, also produced >99% conversion and selectivity towards anisaldehyde, while reducing the reaction time to 30 min and the catalyst load to 0.2 g L−1. The immobilization of gCN-TS in glass rings revealed to be a promising strategy for continuous production of aldehydes without the need of a catalyst separation step.

Recent Progress in Catalytic Oxidative Transformations of Alcohols by Supported Gold Nanoparticles

AbstractCatalytic oxidative transformations of alcohols constitute one of the greatly important protocols for the synthesis of various aldehydes, ketones, acids, imines, amides, etc. that are required to make drug intermediates, food additives, plastics, detergents and cosmetics. The potential of gold nanoparticles (Au NPs) in catalytic oxidation reactions is generally competent owing to their tendency to activate oxygen. Supports play a conspicuous and increasingly important role not only in the preparation and stabilization of Au NPs, but also can address the issues of sustainability by facilitating separation and reusability of the catalyst. This review aims to systematically discuss the impressive developments in catalytic oxidative transformations of alcohols promoted by supported Au NPs in the last five years. These Au NPs exhibit unique electronic properties and crystal structures, which gives us an excellent opportunity to correlate atomic structure with intrinsic catalytic properties over Au NPs. The effect of a support on the significant properties of Au NPs in terms of catalytic activity, selectivity, recyclability, and stability is discussed at length. The tentative reaction mechanisms and the structure‐performance relationships are also discussed at appropriate places, which will provide some clues for the design of efficient Au NPs‐based catalysts.magnified image

Transition-Metal-Free Oxidation of Benzylic C-H Bonds of Six-Membered N-Heteroaromatic Compounds.

A novel oxidation of benzylic C-H bonds for the synthesis of diverse six-membered N-heteroaromatic aldehydes and ketones has been developed. The obvious advantages of this approach are the simple operation, mild reaction conditions, and without use of toxic reagent and transition metal. The present method should provide a useful access for the synthesis and modification of N-heterocycles.

Polymer-incarcerated palladium-catalyzed facile in situ carbonylation for the synthesis of aryl aldehydes and diaryl ketones using CO surrogates under ambient conditions

A palladium-incorporated heterogeneous catalyst, Pd@(Merf-FA), was designed for the synthesis of aryl aldehydes and diaryl ketones using carbonylative surrogates.