One-pot synthesis of ketones and lactones by oxidation of the parent hydrocarbons with KHSO5 catalyzed by manganese(III) porphyrins in a biphasic,solid–liquid,system

The oxidation of alkanes to ketones and lactones by Oxone® (KHSO₄×K₂SO₄×2KHSO₅) catalyzed by manganese porphyrins has been studied in an anhydrous two-phase (solid Oxone®/DCE solution) catalytic system. Under the experimental conditions adopted, i.e., an excess of Oxone® over the organic substrate and catalytic amount of Mn(TDCPP)Cl, almost complete hydrocarbon conversions are obtained. Acyclic alkanes give ketones as main oxygenated product whereas cyclic alkanes give mainly lactones together with minor amounts of alcohols and ketones. The overall process leading to lactones involves two subsequent manganese porphyrin catalyzed oxidative steps and a stoichiometric reaction involving monopersulfate and the intermediate ketone. The lack of a water phase and of strong acids prevents the hydrolysis of the lactones formed. The products are obtained in yields ranging from low to fair depending on the nature of substrate, catalyst, and on phase transfer agent concentration.     

Hydrogenation of Esters to Alcohols Catalyzed by Defined Manganese Pincer Complexes

The first manganese‐catalyzed hydrogenation of esters to alcohols has been developed. The combination of Mn(CO)₅Br with [HN(CH₂CH₂P(Et)₂)₂] leads to a mixture of cationic and neutral Mn PNP pincer complexes, which enable the reduction of various ester substrates, including aromatic and aliphatic esters as well as diesters and lactones. Notably, related pincer complexes with isopropyl or cyclohexyl substituents showed very low activity.     

Nickel‐Catalyzed Homoallylation of Aldehydes and Ketones with 1,3‐Dienes and Complementary Promotion by Diethylzinc or Triethylborane

Regio‐ and stereoselective homoallylation of saturated aldehydes and ketones to give bishomoallyl alcohols 1,3‐anti‐ 1 is achieved with [Ni(acac)₂] (cat.) and Et₂Zn [Eq. (a)]. This new catalyst system thus complements the previously reported combination of [Ni(acac)₂] with Et₃B, which offers advantages in the homoallylation of unsaturated and aromatic aldehydes. acac=acetylacetonato.     

Zirconium borohydride piperazine complex, an efficient, air and thermally stable reducing agent

A zirconium borohydride piperazine complex (Ppyz)Zr(BH₄)₂Cl₂, obtained by the reaction of an ethereal solution of ZrCl₄ and LiBH₄ with piperazine is a stable, selective and efficient reducing agent. (Ppyz)Zr(BH₄)₂Cl₂ reduces aldehydes, ketones, silylethers, α,β-unsaturated carbonyl compounds and esters. The reactions were performed in diethyl ether at room temperature or under reflux, and the yields of the corresponding alcohols were excellent. The selective reduction of aldehydes in the presence of ketones and complete regioselectivity in the reduction of α,β-unsaturated carbonyl groups were observed.     

A new and highly effective method for catalytic oxidation of alcohols to the corresponding carbonyl compounds using the tris[(2-oxazolinyl)phenolato]manganese(III)/Oxone®/n-Bu4NBr oxidation system

Oxone® (2KHSO₅·KHSO₄·K₂SO₄) in the presence of mer-tris[(2-oxazolinyl)phenolato]manganese(III), Mn(phox)₃, as catalyst under biphasic reaction conditions (CH₂Cl₂/H₂O) and tetra-n-butylammonium bromide as phase transfer agent efficiently oxidises alcohols to their corresponding aldehydes and ketones at room temperature with very short reaction times (5 min) and good to quantitative yields.     

Transformation of Oximes and Alcohols to Carbonyl Compounds Using Amberlite IRA-400 Supported Chromic Acid in the Presence of Zirconium Tetrachloride

A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method. A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method.     

The Mn(acac)3—RCN—CCl4 system as a new efficient reagent for the oxidation of secondary alcohols into ketones

The Mn(acac)₃—RCN—CCl₄ system was found to be efficient for the oxidation of secondary alcohols into the corresponding ketones in 80—93% yields. The oxidation proceeds through the formation of alkyl hypochlorites, which are generated from CCl₄ and the alcohols in the presence of the Mn(acac)₃—RCN catalytic system (R = Me, Et, and Ph).     

Vanadium-catalyzed selective aerobic alcohol oxidation in ionic liquid [bmim]PF6

A selective aerobic oxidation of alcohols into the corresponding aldehydes or ketones was developed by using two-component system VO(acac)₂/DABCO in the ionic liquid [bmim]PF₆, and the catalysts can be recycled and reused for three runs without any significant loss of catalytic activity.     

Barbier coupling in water: SnCl2-mediated and Co(acac)2-catalyzed allylation of carbonyls

Co(acac)₂·2H₂O efficiently catalyzes SnCl₂-mediated Barbier coupling in water between carbonyls, including aromatic, aliphatic and α,β-unsaturated aldehydes, ketones, sugars and allyl bromide to afford the corresponding homoallylic alcohols in high yields. The catalyst was reused for several cycles with consistent activity.     

Intercalation chemistry of layered vanadyl phosphate: a review

The intercalation chemistry of layered α_I modification of vanadyl phosphate and vanadyl phosphate dihydrate is reviewed. The focus is on neutral molecular guests and on metal cations used as guest species. The basic condition for the ability of the neutral molecules to be intercalated into vanadyl phosphate is a presence of an electron donor atom in them. The most commonly used guest compounds are those containing oxygen, nitrogen or sulfur as electron donor atoms. Regarding the molecules containing oxygen, various compounds were used as molecular guests starting from water to alcohols, ethers, aldehydes, ketones, carboxylic acids, lactones, and esters. An arrangement of the guest molecules in the interlayer space is discussed in connection with the data obtained by powder X-ray diffraction, thermogravimetry, IR and Raman spectroscopies, and solid-state NMR. In some cases, the local structure was suggested on the basis of quantum chemical calculations. Besides of those O-donor guests, also N-donor guests such as amines, nitriles and nitrogenous heterocycles and S-donor guests such as tetrathiafulvalene were intercalated into VOPO₄. Also intercalates of complexes like ferrocene were prepared. Intercalation of cations is accompanied by a reduction of vanadium(V) to vanadium(IV). In this kind of intercalation reactions, an iodide of the intercalated cation is often used as it serves both as a mild reduction agent and as a source of the intercalated species. Intercalates of alkali metals, hydronium and ammonium were prepared and characterized. In the case of lithium and sodium intercalates, a staging phenomenon was observed. These redox intercalated vanadyl phosphates undergo ion exchange reactions which are discussed from the point of the nature of cations involved in the exchange. Vanadyl phosphates in which a part of vanadium atom is replaced by other metals are also briefly reviewed.     

Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones,Esters, Amides,and α-Ketoamides

A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C−C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O₂) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.     

Oxidation of alcohols by transition metal complexes—iv : The rhodium catalysed synthesis of esters from aldehydes and alcohols

Both RhH(CO)PPh₃)₃ and a catalyst made in _situ from RhCl₃·3H₂O, PPh₃ and Na₂CO₃ catalyse the reaction of a range of aldehydes with simple primary alcohols to give esters together with alcohols formed by reduction of the aldehydes. The proportion of ester can be increased by adding an efficient hydrogen acceptor. The reaction can also be used to produce 5- and 7-membered lactones from aromatic dialdehydes. Propan-2-ol and the _{in situ} catalyst reduce some aromatic aldehydes to the corresponding alcohols without concomitant ester formation.     

Beiträge zur Chemie der Alkylverbindugen von Übergangsmetallen. XXIX. Dibenzylmangan – Darstellung und Reaktionen

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXIX. Dibenzyl Manganese – Preparation and Reactions Manganese(II) acetylacetonate reacts with tribenzyl aluminium and dibenzyl magnesium forming the yellow complexes 3(C₆H₅CH₂)₂Mn · Al(acac)₃ and (C₆H₅CH₂)₂Mn · Mg(acac)₂ Dibenzyl manganese is also formed at the reaction of dibenzyl magnesium or benzyl magnesium chloride with MnCl₂ · 1.5 THF and was separated as the dioxan complex (C₆H₅CH₂)₂Mn · 2C₄H₈O₂, the ligands of which can be removed to a great extent in vacuum. Dibenzyl manganese reacts with CO₂, CS₂ and SO₂ with insertion into the Mn–C-bonds. The corresponding manganese compounds were isolated and furtherly characterized.     

Oxidation of Organic Compounds by Sulfonated Porous Carbon and Hydrogen Peroxide

 The oxidation of organic compounds by sulfonated porous carbon and H2O2 was studied at room temperature. Alkyl and aryl sulfides were oxidized to the corresponding sulfoxides or sulfones in excellent yields. Secondary alcohols were also converted to the corresponding esters/lactones and aldehydes to methyl esters in good yields. Moreover, aliphatic tertiary amines and substituted pyridines were oxidized to N-oxides.     

O-Silylated enolates in organic synthesis: α-Alkylation of carbonyl compounds by 1,3-dithienium fluoroborate.

The O-silylated enolates of ketones, aldehydes, esters, and lactones can be regiospecifically alkylated by 1,5-dithienium fluoroborate to give the selectivity protected β-dicarbonyl compounds.     

α-Alkylation and α-alkylidenation of carbonyl compounds: Lewis acid-promoted phenylthioalkylation of o-silylated enolates

The O-silylated enolates of ketones, aldehydes, esters, and lactones can be phenylthioalkylated in the presence of Lewis acids; reductive or oxidative sulphur-removal gives the regiospecifically α-alkylated or alkylidenated carbonyl compounds.     

Oxidant-dependent selective oxidation of alcohols utilizing multinuclear copper-triethanolamine complexes

Multinuclear Cu(II)-triethanolamine complexes were employed as catalysts for the selective oxidation of primary and secondary alcohols using tert-butylhydroperoxide (TBHP) and O₂/2,2′,6,6′-tetramethylpiperidinyl-1-oxyl (TEMPO) system, respectively. The catalytic performances, especially in terms of selectivities, were oxidant-dependent in forming the corresponding carbonyl compounds as the major products. Excellent selectivities and moderate to good yields were obtained for the transformation of secondary alcohols to ketones in the case of TBHP and also for the conversion of benzylic primary alcohols to aldehydes in the case of O₂/TEMPO system.     

Oxidation of monohydric and dihydric alcohols with CCl4 catalyzed by molybdenum compounds

Mo(CO)₆ catalyzed oxidation of alcohols and diols with tetrachloromethane. Primary oxidation products in reaction of alcohols with CCl₄ are alkyl hypochlorites, and final products depending on the structure of initial alcohol are aldehydes (as acetals), ketones, chloroketones, and esters.     

Manganese(II) β-diketonate catalyzed oxidation of cyclohexane bytert-butyl hydroperoxide

Oxidation of cyclohexane bytert-butyl hydroperoxide was carried out in acetonitrile solution at room temperature in the presence of manganese(II) β-diketonate complexes, Mn(acac)₂, Mn(acac)₂.2H₂O, Mn(ba)₂.H₂O, Mn(dbm)₂ and Mn(dbm)₂.2H₂O (where acacH=acetylacetone, baH=benzoylacetone and dbmH=dibenzoyl-methane). Cyclohexanol and cyclohexanone were obtained as the products. Oxidation ofcis-cyclooctene gave the corresponding epoxide together with two minor byproducts in the presence of Mn(acac)₂.2H₂O and Mn(dbm)₂.2H₂O. A mechanistic pathway predominantly involving autoxidation is proposed. IPCL communication No. 322     

Solvent and salt effects on the redox behaviour of trisacetylacetonato manganese(III)

The polarographic and voltammetric behaviour of trisacetylacetonato manganese(III) [Mn(acac)₃] has been studied in methanol, ethanol, tetrahydrofurane, butyrolactone, propylenecarbonate, N,N-dimethylformamide, acetonitrile, nitromethane, N-methylpyrrolidone(2), 1,2-dichloroethane, dichloromethane, dimethylsulfoxide and acetic acid, Mn(acac)₃ was found to undergo a reversible one-electron reduction to Mn(acac)₃^? in most of the solvents mentioned. A further reduction at very negative potentials has been also observed in several solvents. The oxidation of Mn(acac)₃ to Mn(acac)₃⁺ has been studied by cyclovoltammetry in dichloromethane, nitromethane, acetonitrile, propylenecarbonate, N-methylpyrrolidinone(2), N,N-dimethylformamide and dimethylsulfoxide. The polarographic behaviour of NaMn(acac)₃ and Mn(acac)₂ has been investigated in the seven solvents listed above as well as in methanol. The half-wave potentials and the peak potentials referred to bisbiphenylchromium(I)/bisbiphenylchromium(0) as a reference redox system were found to vary with the nature of the solvent. Conductivity studies of Mn(acac)₃ and NaMn(acac)₃ have been carried out in these solvents. U.v.-visible and near i.r. spectra have been recorded of Mn(acac)₃, NaMn(acac)₃, Mn(acac)₂ and Na(acac) in the solvents mentioned. It has further been observed that the half-wave potentials for the polarographic reduction of Mn(acac)₃ shifted to more positive values by the addition of alkali metal ions and to more negative values by the addition of halide ions. The interactions of the solvent with Mn(acac)₃ and the variation of redox potentials with both the solvent and the added electrolytes will be discussed.