Parent Carbonyl Compounds Research Articles

Microwave-Assisted Chemoselective Cleavage of Oximes to Their Corresponding Carbonyl Compounds Using 1,3-Dichloro-5,5-dimethyl-hydantoin (DCDMH) as a New Deoximating Reagent

In the presence of alkene and alcohol, oximes are converted into their parent carbonyl compounds in good yields when treated with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) (1), under microwave irradiation. The simple work-up minimizes loss of products.

Reinvestigation of the Mechanism of gem‐Diacylation: Chemoselective Conversion of Aldehydes to Various gem‐Diacylates and Their Cleavage under Acidic and Basic Conditions

AbstractThe mechanism of gem‐diacylate formation has been studied extensively using tetrabutylammonium tribromide (TBATB) as the catalyst. The reaction proceeds by a nucleophilic attack of an anhydride on an aldehydic carbonyl group, nucleophilic attack of the hemiacylate intermediate on a second molecule of the anhydride, followed by an intermolecular attack of a second acetate group to regenerate the anhydride. gem‐Diacylates of various aliphatic and aromatic aldehydes were obtained directly from the reaction of a variety of aliphatic and aromatic acid anhydrides in the presence of a catalytic quantity of tetrabutylammonium tribromide (TBATB) under solvent‐free conditions. A significant electronic effect was observed during its formation as well as deprotection to the corresponding aldehyde. Chemoselective gem‐diacylation of the aromatic aldehyde containing an electron‐donating group has been achieved in the presence of an aldehyde containing an electron‐withdrawing group. Deprotection of the gem‐diacylate to the parent carbonyl compound can be accomplished in methanol in presence of the same catalyst. Here again, chemoselective deprotection of the gem‐diacylate of a substrate containing an electrondonating group has been achieved in the presence of a substrate containing an electron‐withdrawing group. Both the acid and base stability order of the various gem‐diacylates examined follow a similar order. The stability order determined from the present study is: gem‐dibenzoate > gemdipivalate > gem‐diisobutyrate > gem‐diacetate > gem‐dipropionate. All the gem‐diacylals are more stable under basic conditions than acidic condition. No correlation was found between the stability order and the pKa’s of the corresponding acids; rather, the stability order is directly related to the steric crowding around the carbonyl carbon. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

CARO'S ACID SUPPORTED ON SILICA GEL. PART VI. A MILD REAGENT FOR REGENERATION OF CARBONYL COMPOUNDS FROM ACETALS, KETALS, AND 1,1-DIACETATES

Efficient conversion of acetals, ketals, and diacetates to carbonyl compounds is described using Caro's acid supported on silica gel. The deacetalization reactions are carried out in acetonitrile at room temperature. Reaction of diacetates is performed in refluxing dichloromethane, and their parent carbonyl compounds are obtained in good-to-excellent yields.

Facile and Chemoselective Microwave-Assisted Cleavage of Oximes to Their Corresponding Carbonyl Compounds Using N,N′ -Dibromo- N,N′-1,3-propylene- bis[(4-methylphenyl)sulfonamide] as a Deoximating Reagent

Aldoximes and ketoximes are converted to the parent carbonyl compounds in good yields when treated with N,N′-dibromo-N,N′-1,3-propylene-bis[(4-methylphenyl)sulfonamide] (2) under microwave irradiation. The simple workup minimizes the loss of product and oximes have been selectively oxidized in the presence of alcohols and alkenes.

N,N‐Dibromobenzenesulfonamide as a Reagent for Oxidative Cleavage of Oximes to Their Parent Carbonyl Compounds under Non‐Aqueous and Aprotic Conditions.

Deprotection of different oximes to their parent aldehydes and ketones in high yields has been carried out by using N,N-dibromobenzenesulfonamide(dibromoamine-b) under mild conditions.

Organocatalyzed asymmetric alpha-aminoxylation of aldehydes and ketones--an efficient access to enantiomerically pure alpha-hydroxycarbonyl compounds, diols, and even amino alcohols.

The magic of no metal: Enantiomerically pure α-hydroxy aldehydes and ketones as well as diols can be synthesized by a direct (S)-proline-catalyzed asymmetric nitroso-aldol reaction between the parent carbonyl compound and nitrosobenzene. Further elaboration of the obtained adducts provides useful precursors for diversity-oriented synthesis. The one-flask transformation of 3-phenylpropanal into (R)-3-phenylpropane-1,2-diol (98 % ee) is one example.

Quinolinium Fluorochromate as a Reagent for Selective Oxidative Cleavage of Oximes and Phenylhydrazones to Their Parent Carbonyl Compounds under Non‐Aqueous and Aprotic Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Kinetics and mechanism of the oxidative regeneration of carbonyl compounds from phenylhydrazones by [bis(trifluoroacetoxy)iodo]benzene

The oxidation of several aldo- and keto-phenylhydrazones by [bis(trifluoroacetoxy)iodo]benzene (TFAIB), in aqueous acetic acid leads to the regeneration of the parent carbonyl compounds. The reaction exhibits a first order dependence on both the phenylhydrazone and TFIAB. The oxidation of ketoximes is slower than that of aldoximes. The oxidation of aliphatic phenylhydrazones correlates well in terms of Pavelich–Taft dual substituent-parameter equation. The low positive value of the polar reaction constant indicates a nucleophilic attack by TFIAB on the carbonyl carbon. The reaction is subject to steric hindrance by the alkyl group. A mechanism involving the formation of a cyclic activated complex in the rate-determining step is proposed.

Diaryl diselenides and benzisoselenazol-3(2H)-ones as oxygen-transfer agents

Diaryl diselenides and related benzisoselenazol-3(2H)-ones are presented as the catalyst for hydogen peroxide and t-butylhydroperoxide oxidation of various types of organic substrates. Most of the reactions studied in our laboratory have a practical value. The aromatic aldehydes and ketones are oxidized to arenecarboxylic acids or converted to the phenols while cycloalkanones gave cycloalkanecarboxylic acids with ring contraction. From the azomethine compounds, depending on their structure, nitriles, parent carbonyl compounds, carboxylic acids or their esters are produced. Primary benzylamines gave nitriles, while the secondary are oxidized to nitrones. Alkylarenes are oxidized to the alkylaryl ketones and alkenes to epoxides. By oxidation of 1,4-dimethoxysubstituted and some polycondensed arenes the quinones are produced. The postulated mechanisms are discussed and the methods for synthesis of the title compounds are described.

N,N-Dibromobenzenesulfonamide as a Reagent for Oxidative Cleavage of Oximes to Their Parent Carbonyl Compounds Under Non-Aqueous and Aprotic Conditions

Deprotection of different oximes to their parent aldehydes and ketones in high yields has been carried out by using N,N-dibromobenzenesulfonamide(dibromoamine-b) under mild conditions.

Antioxidation capacity of Maillard systems with carbonyl products of sugar fragmentation

A role of reactive C<sub>2</sub>-C<sub>5</sub> α-dicarbonyl and α-hydroxycarbonyl products of sugar fragmentation in the development of antioxidative activity (AOA) was investigated after heating in 0.5M binary aqueous mixtures with amino acids. Several kinetic and activity parameters related to the development of reducing power in the systems with different carbonyl fragments as well as glucose were evaluated and compared. The formation of electrochemically active compounds was correlated with colour development. To assess the antioxidation effects more properly, several different methods were used for AOA evaluation of the systems tested in addition to the HPLC-ECD method. Tests with scavenging of radicals or assays evaluating oxidation in different media (hydrophobic, hydrophilic, emulsions) were employed. Biacetyl was found as by far the most powerful precursor of reducing activity among the fragments tested. The major products possessing reducing power were isolated and characterized revealing dihydroxy dimethylbenzene structures. Based on the comparison of the same concentrations of BHA and a parent carbonyl compound, AOA found by different methods in the most powerful systems is fully comparable with BHA efficiency.

Quinolinium fluorochromate as a reagent for selective oxidative cleavage of oximes and phenylhydrazones to their parent carbonyl compounds under non-aqueous and aprotic conditions

Deprotection of oximes and phenylhydrazones to their parent aldehydes and ketones in high yields has been carried out by using quinolinium fluorochromate as a selective oxidant under mild conditions.

Selenium‐Promoted Oxidation of Organic Compounds: Reactions and Mechanisms

AbstractOxidation reactions are fundamental processes widely applied in organic synthesis. Elemental selenium and more often its compounds have been successfully used as stoichiometric reagents and catalysts for oxidation of different organic substrates. Selenium(IV) oxide, areneseleninic acids and their anhydrides are widely used as stoichiometric oxidants or as oxygen‐transfer agents for oxygen donors, particularly hydrogen peroxide andtert‐butyl hydroperoxide. Organic diselenides (the precursors of seleninic acids) have been used as oxidation catalysts while dimethyl and diphenyl selenoxides are stoichiometric oxidants. Selenenamides, such as 2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one (ebselen) and its analogues, known as glutathione peroxidase mimics acting via active hydroperoxide intermediates, are efficient and selective oxidation catalysts. Selenium(IV) oxide and some organoselenium compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2‐dihydroxylation, and α‐oxyfunctionalization of alkenes as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl, or active methylene groups into formyl groups, oxidation of aldehydes into carboxylic acids, sulfides into sulfoxides, and secondary amines into nitrones, regeneration of parent carbonyl compounds from their azomethine derivatives and for other reactions. The oxidation mechanisms depend on the substrate and oxidant or catalyst used. The electrophilic center localized on the selenium atom or the nucleophilic center localized on the oxygen atom of the selenahydroperoxide group are involved in the reaction mechanism. In both cases the selenium‐containing moiety is a good leaving group. Exceptionally oxidation can proceed via free radical selenium species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Highly Efficient, and Fast Solid State Deprotection of 1,3-Dithianes and 1,3-Dithiolanes using Mercury(II) Nitrate Trihydrate

A variety of 1,3-dithianes and 1,3-dithiolanes are deprotected in the solid state to the corresponding parent carbonyl compounds in excellent yields using mercury(II) nitrate trihydrate in a mild, efficient and fast method.

Deposition of Conductive Ru and RuO2 Thin Films Employing a Pyrazolate Complex [Ru(CO)3(3,5‐(CF3)2‐pz)]2 as the CVD Source Reagent

AbstractThe reaction of Ru3(CO)12 with three equivalent of 3,5‐bis(trifluoromethyl) pyrazole [(3,5‐(CF3)2‐pz)H] at 180 °C produces the double pyrazolate‐bridged ruthenium complex [Ru(CO)3(3,5‐(CF3)2‐pz)]2, (1), in high yield. This ruthenium complex has been characterized by spectroscopic methods, revealing a molecular structure similar to that of the diosmium analogue [Os(CO)3(3,5‐(CF3)2‐pz)]2. Thermogravimetric analysis (TGA) of complex 1 showed an enhanced volatility compared to the parent carbonyl compound Ru3(CO)12 and the closely related, unsaturated 3,5‐di‐tert‐butyl pyrazole complex (2) [Ru2(CO)5(3,5‐t‐Bu2‐pz)2]. Using complex 1 as the CVD source reagent, ruthenium metal with a preferred (002) orientation can be deposited at 400 °C using H2 as the carrier gas. If, however, O2 is used as the carrier gas, RuO2 thin films with a (101) orientation are obtained. The as‐deposited metal thin films were characterized by various surface techniques, as well as by electrical resistivity measurements.

Conversion of Oximes into Carbonyl Compounds with Thalium(III) Nitrate Supported onto HZSM-5 Zeolite Under Microwave Irradiation in Solventless System

Oximes are oxidatively deprotected by thalium(III) nitrate supported onto HZSM-5 zeolite to the parent carbonyl compounds in high yields upon exposure to microwave irradiation.

A Mild and Selective Deoximation Method Using γ‐Picolinium Chlorochromate (γ‐PCC).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Solid State Deprotection of Acetals and Thioacetals Using Benzyltriphenylphosphonium Peroxymonosulfate

A variety of acetals and thioacetals 2 are deprotected to the corresponding parent carbonyl compounds 3 under solvent-free conditions using benzyltriphenyl-phosphonium peroxymonosulfate (1) in the presence of aluminum chloride.

ChemInform Abstract: A Useful and Catalytic Method for Protection of Carbonyl Compounds into the Corresponding 1,3‐Oxathiolanes and Deprotection to the Parent Carbonyl Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A useful and convenient synthetic protocol for interconversion of carbonyl compounds to the corresponding 1,3-oxathiolanes and vice versa employing organic ammonium tribromide (OATB)

A wide variety of carbonyl compounds 1 can be easily protected selectively as the corresponding 1,3-oxathiolanes 2 in good yields using a catalytic amount (0.01–0.1 equiv.) of n-tetrabutylammonium tribromide in dry CH 2Cl 2 at 0–5 °C. On the other hand, various 1,3-oxathiolanes 2 can be deprotected chemoselectively to the parent carbonyl compounds 1 employing 0.5 equivalents of organic ammonium tribromides under identical conditions in very high yields. Mild conditions, high selectivity and yield, highly efficient, less expensive, and no brominations either at the double bond or allylic position and even α- to the keto position or aromatic ring are some of the major advantages of the protocol.