Synthesis Of Carbonyl Compounds Research Articles

Transition-metal Catalyzed Synthesis of Carbonyl Compounds Using Formates or Formamides as Carbonyl Sources

Various available approaches for catalytic carbonylation reactions using formates and formamides with transition metal catalysts are reviewed. Pd complexes catalyze the hydroesterification or hydrocarbamoylation of alkynes using aryl formates or formamides, respectively, as the carbonyl sources. The esterification of aryl halides with aryl formates proceeds in the presence of a Pd catalyst with suitable ligands. Using a Cu complex with a bulky bidentate phosphine ligand is used as a catalyst, boraformylation and silaformylation of allenes efficiently proceeds using alkyl formates as a formyl source.

Palladium/Copper-Catalyzed Oxidative Coupling of Arylboronic Acids with Isocyanides: Selective Routes to Amides and Diaryl Ketones.

An efficient and alternative oxidative cross-coupling strategy starting from arylboronic acids and isocyanides for the selective synthesis of amides and diaryl ketones with palladium/copper catalysis is developed. Various substituted benzamides and benzophenones could be obtained in good yields. The reaction represents an efficient and alternative strategy for the synthesis of carbonyl compounds.

Visible-Light-Promoted and Photoredox-Catalyzed Radical Addition to Triple Bonds

This account details a series of visible-light-promoted and photoredox-catalyzed radical additions to triple bonds, including those of isocyanides, alkynes, cyanides and carbon monoxide. 6-Substituted phenanthridines, 1-substituted isoquinolines and ortho-substituted pyridine derivatives are synthesized via radical addition to isocyanides. A number of (hetero)aromatic compounds are prepared by the addition of radicals to alkynes. Carbonyl compounds can be easily obtained by radical addition to carbon monoxide. Tetracyclic quinazolinones are constructed by radical addition to cyanides. Furthermore, a wide range of quinoline and quinoxaline derivatives are synthesized by way of domino radical isocyanide/alkyne insertions and isocyanide/cyanide insertions, respectively. All the reactions can be carried out in high yields under mild conditions. 1 Introduction 2 Synthesis of Six-Membered Heteroaromatic Rings by Radical Addition to Isocyanides 2.1 Synthesis of 6-Substituted Phenanthridines 2.2 Synthesis of 1-Substituted Isoquinolines 2.3 Synthesis of ortho-Substituted Pyridines 3 Synthesis of (Hetero)aromatic Compounds by Radical Addition to Alkynes 3.1 Synthesis of Six-Membered (Hetero)aromatic Compounds 3.2 Synthesis of Five-Membered (Hetero)aromatic Compounds 4 Synthesis of Carbonyl Compounds by Radical Addition to Carbon Monoxide 5 Synthesis of Tetracyclic Quinazolinones by Radical Addition to Cyanides 6 Synthesis of Quinolines by Domino Radical Isocyanide/Alkyne Insertions 7 Synthesis of Quinoxalines by Domino Radical Isocyanide/Cyanide Insertions 8 Conclusions and Outlook

ChemInform Abstract: Recent Developments in Tsuji‐Wacker Oxidation

AbstractReview: [70 refs.

Thermodynamically Favorable Synthesis of 2-Oxazolidinones through Silver-Catalyzed Reaction of Propargylic Alcohols, CO2, and 2-Aminoethanols.

Development of catalytic routes to incorporate CO2 into carbonyl compounds at mild conditions remains attractive and challenging. Herein, a one-pot three-component cascade reaction of terminal propargylic alcohols, CO2 , and 2-aminoethanols through Ag(I) -based catalysis is reported for the synthesis of carbonyl compounds through C-O/C-N bond formation. This thermodynamically favorable route can be ingeniously regulated to afford a wide range of 2-oxazolidinones along with concurrent production of α-hydroxyl ketone derivatives in excellent yields and selectivity. Preliminary mechanistic studies indicate that such a process proceeds through successive formation of α-alkylidene cyclic carbonate, β-oxopropylcarbamate, and 2-oxazolidinones.

Asymmetric Catalysis with Ethylene. Synthesis of Functionalized Chiral Enolates.

Trialkylsilyl enol ethers are versatile intermediates often used as enolate surrogates for the synthesis of carbonyl compounds. Yet there are no reports of broadly applicable, catalytic methods for the synthesis of chiral silyl enol ethers carrying latent functionalities useful for synthetic operations beyond the many possible reactions of the silyl enol ether moiety itself. Here we report a general procedure for highly catalytic (substrate:catalyst ratio up to 1000:1) and enantioselective (92% to 98% major enantiomer) synthesis of such compounds bearing a vinyl group at a chiral carbon at the β-position. The reactions, run under ambient conditions, use trialkylsiloxy-1,3-dienes and ethylene (1 atm) as precursors and readily available (bis-phosphine)-cobalt(II) complexes as catalysts. The silyl enolates can be readily converted into novel enantiopure vinyl triflates, a class of highly versatile cross-coupling reagents, enabling the syntheses of other enantiomerically pure, stereodefined trisubstituted alkene intermediates not easily accessible by current methods. Examples of Kumada, Stille, and Suzuki coupling reactions are illustrated.

A review on transition-metal catalyzed C-H bond carbonylation reactions with CO

Carbon monoxide can be used as an inexpensive and readily available C1 source, which is also in agreement with atom economy. Carbonylation reactions with CO have been and continue to be a very active area of research. Since the pioneering work of Heck in 1974, carbonylations of aryl halides and pseudohalides with CO have become one of the most common methods for the addition of a carbonyl group to organic molecules. Recently, transition-metal-catalyzed chelation-assisted carbonylation of C-H bonds for the synthesis of carbonyl compounds. The progress in carbonylation chemistry has been achieved in both academic laboratories and industry. Hence, in this paper, we have reviewed the research work of transition-metal-catalyzed C-H bond carbonylation reactions with CO in recent years. We made introductions of C-H bond carbonylation reactions from three main parts: sp C-H, sp2 C-H and sp3 C-H bond. Some reaction mechanisms were described in the paper. These C-H bonds carbonylation reactions provide a simple and effective method for the synthesis of acids, ketones, esters, amides and anhydrides.

ChemInform Abstract: Efficient Hydration of Alkynes Through Acid‐Assisted Broensted Acid Catalysis.

AbstractThe combined acid catalyzed hydration of alkynes is an efficient one‐step synthesis of carbonyl compounds.

ChemInform Abstract: Cu(II) 2‐Quinoxalinol Salen Catalyzed Oxidation of Propargylic, Benzylic, and Allylic Alcohols Using tert‐Butyl Hydroperoxide in Aqueous Solutions.

Abstract The synthesis of carbonyl compounds by oxidation of alcohols is a key reaction in organic synthesis. Such oxidations are typically conducted using catalysts featuring toxic metals and hazardous organic solvents. Considering green and sustainable chemistry, a copper(II) complex of sulfonated 2-quinoxalinol salen (sulfosalqu) has been characterized as an efficient catalyst for the selective oxidation of propargylic, benzylic, and allylic alcohols to the corresponding carbonyl compounds in water when in combination with the oxidant tert-butyl hydroperoxide. The reactions proceed under mild conditions (70 °C in water) to produce yields up to 99% with only 1 mol % of catalyst loading. This reaction constitutes of a rare example of propargylic alcohol oxidation in water, and it makes this process greener by eliminating the use of hazardous organic solvents. Excellent selectivity was achieved with this catalytic protocol for the oxidation of propargylic, benzylic, and allylic alcohols over aliphatic alcohols. The alcohol oxidation is thought to go through a radical pathway.

Efficient hydration of alkynes through acid-assisted Brønsted acid catalysis.

The combined acid catalyzed hydration of alkynes is an efficient one-step synthesis of carbonyl compounds. This atom-economical method is effective with a wide range of substrates, and the products are obtained in very good yields with low catalyst loading (0.2%). Furthermore, solid acids like Nafion were also efficient and could be easily recycled multiple times without loss of reactivity.

Cu(II) 2-quinoxalinol salen catalyzed oxidation of propargylic, benzylic, and allylic alcohols using tert-butyl hydroperoxide in aqueous solutions

The synthesis of carbonyl compounds by oxidation of alcohols is a key reaction in organic synthesis. Such oxidations are typically conducted using catalysts featuring toxic metals and hazardous organic solvents. Considering green and sustainable chemistry, a copper(II) complex of sulfonated 2-quinoxalinol salen (sulfosalqu) has been characterized as an efficient catalyst for the selective oxidation of propargylic, benzylic, and allylic alcohols to the corresponding carbonyl compounds in water when in combination with the oxidant tert-butyl hydroperoxide. The reactions proceed under mild conditions (70 °C in water) to produce yields up to 99% with only 1 mol % of catalyst loading. This reaction constitutes of a rare example of propargylic alcohol oxidation in water, and it makes this process greener by eliminating the use of hazardous organic solvents. Excellent selectivity was achieved with this catalytic protocol for the oxidation of propargylic, benzylic, and allylic alcohols over aliphatic alcohols. The alcohol oxidation is thought to go through a radical pathway.

アルデヒド類の脱カルボニル化を基軸としたカルボニル化合物の新合成法

Formyl compounds represent one of synthetic integrants essential for the construction of complex organic molecules. In general, their activation at the carbonyl carbon by a Brønsted or Lewis acid has been used for the new bond formation at the carbon with a wide variety of nucleophiles. On the other hand, transition metal, especially late transition metal, complexes often activate a formyl C-H bond to generate an acylmetal hydride species (RC(=O)-M-H), which can react with a C-C unsaturated bond, leading to the hydroacylation. Furthermore, the C-H bond cleavage, followed by the migratory extrusion of the carbonyl moiety, generates a metal carbonyl species (M-CO) along with the release of R-H. This is recognized as the decarbonylation. The account describes a novel method for synthesis of carbonyl compounds, in which the decarbonylation process of formyl compounds is used as a carbonyl-donating process (CO gas-free carbonylation). It provides more reliable and accessible carbonylation reactions for synthetic organic chemists.

Solvent free clean selective oxidation of alcohols catalyzed by mono transition metal (Co, Mn, Ni)-substituted Keggin-phosphomolybdates using hydrogen peroxide

Traditional procedures for synthesis of carbonyl compounds suffer from a lack of selectivity, use of organic solvents, toxicity of the reagents, and waste production. As a cleaner alternative, an environmentally benign solvent free oxidation of alcohols catalyzed by mono transition metal-substituted Keggin-phosphomolybdates, PMo11M (M=Co, Mn, Ni) using hydrogen peroxide was carried out under mild conditions. The influence of different parameters such as mole ratio of benzyl alcohol to H2O2, amount of the catalyst, reaction time and reaction temperature on oxidation of benzyl alcohol was investigated. Further, oxidation of various alcohols such as cyclopentanol, 1-hexanol and 1-octanol with PMo11M was carried out under optimized conditions. The catalytic activity of recycled catalysts was also evaluated and it was found that catalysts are stable under present reaction conditions. All the catalysts are very much efficient, especially in terms of % selectivity of the desire product.

Synthesis of Carbonyl Compounds from Alcohols Using Electrochemically Generated Superoxide Ions in RTILs

We show that the superoxide ion (O2 •−) generated electrochemically from oxygen dissolved in room-temperature ionic liquids (RTILs) reacts with primary and secondary alcohols to form the corresponding ketones and carboxylic acids, respectively. Specifically, we study the conversion of benzhydrol to benzophenone and benzyl alcohol to benzaldehyde/benzoic acid. The kinetics (e.g., rate, selectivity, and yield) for these reactions are also determined as functions of the variations in the structure of the ionic liquids. The RTILs used here are imidazolium-based cations where the functional groups on the imidazolium ring are modified. Specifically, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], 1-butyl-2,3-dimethylimidazolium hexafluorophosphate [bdmim][PF6], and 1-hexyl-3-methylimidazolium hexafluorophosphate [hmim][PF6] are used as the reaction medium. These results are compared to an ammonium-based RTIL (N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide). The results show that the nucleophilic attack by the O2 •− of both the RTIL and the alcohol, especially that of the H atom at the R2 position of the [bmim][PF6] and [hmim][PF6], greatly affects the yields. No RTIL degradation products were detected for the reactions in [bdmim][PF6] and N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide ionic liquids. For the benzyl alcohol oxidation reaction in the RTIL, N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide, benzaldehyde formed did not undergo further oxidation to form benzoic acid, which may be due to the greater hydrophobicity of this RTIL. The competitive reaction kinetics between the alcohol and RTIL component must be considered in the selection of the RTIL solvent system.

ChemInform Abstract: Efficient Synthesis of Carbonyl Compounds: Oxidation of Azides and Alcohols Catalyzed by Vanadium Pentoxide in Water Using tert‐Butylhydroperoxide.

AbstractBenzylic azides are conveniently oxidized to the corresponding acids or ketones.

Solvent-free hydration of alkynes over a heterogeneous silver exchanged silicotungstic acid catalyst

Silver exchanged silicotungstic acid (AgSTA) catalysts were prepared and characterized by X-ray diffraction, FT-IR spectroscopy, laser Raman, temperature programmed desorption of ammonia, FT-IR pyridine adsorption and X-ray photo electron spectroscopy. The activity of the catalysts was evaluated for the hydration of non-activated alkynes to corresponding carbonyl compounds without addition of any acid co-catalyst under solvent-free conditions. The highest catalytic activity was obtained for the catalyst with partially silver exchanged STA. This catalytic system provides one of the most straight forward syntheses of carbonyl compounds from terminal alkynes with Markovnikov-type regioselectivity. The catalyst can be recovered by simple filtration and is reusable without loss of activity and selectivity. A plausible reaction mechanism for the AgSTA catalyzed hydration of alkynes is proposed.

Efficient synthesis of carbonyl compounds: oxidation of azides and alcohols catalyzed by vanadium pentoxide in water using tert-butylhydroperoxide

Catalytic amount of vanadium reagent with tert-butylhydroperoxide as the oxidant was found to be an excellent oxidizing agent in aqueous medium. Vanadium pentoxide with aq tert-butylhydroperoxide readily oxidizes primary benzylic azides to the corresponding acids and secondary benzylic azides to the corresponding ketones in excellent yields. Further, vanadium pentoxide and aq tert-butylhydroperoxide combination turned out to be an effective catalyst for the oxidation of alcohols. Using vanadium pentoxide and aq tert-butylhydroperoxide primary alcohols were oxidized to the corresponding acids, whereas secondary alcohols underwent a smooth transformation to furnish corresponding ketones in excellent yields. All the oxidations are performed in water.

Mild and Selective Vanadium-Catalyzed Oxidation of Benzylic, Allylic, and Propargylic Alcohols Using Air

Transition metal-catalyzed aerobic alcohol oxidation is an attractive method for the synthesis of carbonyl compounds, but most catalytic systems feature precious metals and require pure oxygen. The vanadium complex (HQ)(2)V(V)(O)(O(i)Pr) (2 mol %, HQ = 8-quinolinate) and NEt(3) (10 mol %) catalyze the oxidation of benzylic, allylic, and propargylic alcohols with air. The catalyst can be easily prepared under air using commercially available reagents and is effective for a wide range of primary and secondary alcohols.

ChemInform Abstract: An Efficient Electrochemical Method for the Paired Synthesis of Carbonyl Compounds and Homoallylic Alcohols in a Simple Home‐Made Cell

AbstractElectrochemical anodic oxidation of alcohols to carbonyl compounds followed by electrochemical cathodic allylation affords the homoallyl alcohols in good yields.

ChemInform Abstract: Unified Oxidation Protocol for the Synthesis of Carbonyl Compounds Using a Manganese Catalyst.

AbstractThe use of MnCl2/BTP and MCPBA or KHSO5 offers an efficient and selective protocol for the oxidation of a variety of ethers, benzylic compounds and alcohols.