- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
-
Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
-
supporting information
(2021/06/03)
-
- Chemoselective Hydrogenation of α,β-Unsaturated Carbonyls Catalyzed by Biomass-Derived Cobalt Nanoparticles in Water
-
Herein, we report highly chemoselective hydrogenation of α,β-unsaturated carbonyls to saturated carbonyls catalyzed by cobalt nanoparticles supported on the biomass-derived carbon from bamboo shoots with molecular hydrogen in water, which is the first prototype using a heterogeneous non-noble metal catalyst for such organic transformation as far as we know. The optimal cobalt nanocatalyst, CoOx@NC-800, manifested remarkable activity and selectivity for hydrogenation of C=C in α,β-unsaturated carbonyls under mild conditions. A broad set of α,β-aromatic and aliphatic unsaturated carbonyls were selectively reduced to their corresponding saturated carbonyls in up to 99 % yields with good tolerance of various functional groups. Meanwhile, a new straightforward one-pot cascade synthesis of saturated carbonyls was realized with high activity and selectivity via the cross-aldol condensation of ketones with aldehydes followed by selective hydrogenation. More importantly, this one-pot strategy is applicable for the expedient synthesis of Loureirin A, a versatile bioactive and medicinal molecule, from readily available starting materials, further highlighting the practical utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without significant loss in both activity and selectivity.
- Song, Tao,Ma, Zhiming,Yang, Yong
-
p. 1313 - 1319
(2019/01/25)
-
- Heterogeneous Ru(iii) oxidation catalysts: Via 'click' bidentate ligands on a periodic mesoporous organosilica support
-
A 100% monoallyl ring-type Periodic Mesoporous Organosilica (PMO) is prepared as a novel, versatile and exceptionally stable catalytic support with a high internal surface area and 5.0 nm pores. Thiol-ene 'click' chemistry allows straightforward attachment of bifunctional thiols (-NH2, -OH, -SH) which, exploiting the thioether functionality formed, give rise to 'solid' bidentate ligands. [Ru(acac)2(CH3CN)2]PF6 is attached and complex formation on the solid is studied via density functional theory. All resulting solid catalysts show high activity and selectivity in alcohol oxidation reactions performed in green conditions (25 °C/water). The PMO catalysts do not leach Ru during reaction and are thus easily recuperated and re-used for several runs. Furthermore, oxidation of poorly water-soluble (±)-menthol illustrates the benefits of using hydrophobic PMOs as catalytic supports.
- Clerick, Sander,De Canck, Els,Hendrickx, Kevin,Van Speybroeck, Veronique,Van Der Voort, Pascal
-
p. 6035 - 6045
(2018/06/06)
-
- 3,4-Dihydroisoquinolinium trichloroacetatochromate: A mild and effective new reagent for oxidation of alcohols to carbonyl compounds and arenes to their quinones
-
A new chromium(VI) reagent, 3,4-dihydroisoqinolinium trichloroacetatochromate was prepared by reacting trichloroacetic acid with CrO3in water. This reagent is suitable to oxidize various primary and secondary alcohols to the corresponding carbonyl compounds and anthracene to antraquinone in a good yields.
- Ozen, Recep
-
p. 6081 - 6083
(2015/02/19)
-
- ALPHA-HYDROGEN SUBSTITUTED NITROXYLS AND DERIVATIVES THEREOF AS CATALYSTS
-
The present invention relates to novel alpha-hydrogen substituted nitroxyl compounds and their corresponding oxidized (oxoammonium cations) and reduced (hydroxylamine) forms, and to the use of such compounds, inter alia, for (1) oxidation of primary and secondary alcohols to aldehydes and ketones, respectively; (2) resolution of racemic alcohols; (3) desymmetrization of meso-alcohol; (4) as radicals and spin trapping reagents; and (5) as polymerization agents. The present invention further relates to processes for preparing the novel nitroxyl/oxoammonium/ hydroxylamine compounds from the corresponding amines, and to certain novel amine derivatives and their uses. The compounds of the invention as well as the amine precursors are also useful as ligands for transition metals and as organocatalysts in e.g., aldol reactions.
- -
-
Page/Page column 37
(2013/08/28)
-
- Grafting of oxo-vanadium Schiff base on graphene nanosheets and its catalytic activity for the oxidation of alcohols
-
Graphene oxide was found to be a convenient and efficient supporting material for grafting of oxo-vanadium Schiff base via covalent attachment. The low dimensionality and rich surface chemistry of graphene oxide play critical roles in order to achieve a good degree of such grafting. Catalytic potential of the so prepared graphene-bound oxo-vanadium Schiff base and comparison with its homogeneous analogue was studied for the oxidation of various alcohols to carbonyl compounds using tert-butylhydroperoxide as oxidant. The structural and chemical nature of the catalyst was characterized by a variety of techniques including XRD, FTIR, TGA, TEM, and ICP-AES. The immobilized complex was found to be highly efficient and showed comparable catalytic reactivity as its homogenous analogue with the added benefits of facile recovery and recycling of the heterogeneous catalyst. The graphene-bound oxo-vanadium Schiff base was successfully reused for several runs without significant loss in its catalytic activity. The Royal Society of Chemistry 2012.
- Mungse, Harshal P.,Verma, Sanny,Kumar, Neeraj,Sain, Bir,Khatri, Om P.
-
experimental part
p. 5427 - 5433
(2012/06/15)
-
- Cyclization of citronellal in a supercritical solvent in a flow reactor in the presence of Al2O3
-
The reactivity of citronellal under supercritical solvent conditions in a flow reactor in the presence of Al2O3 is examined. It is shown that at 160°C, the main transformation product of citronellal is isopulegol, and when the temperature is increased to 190°C, they are monoterpenes with a para-menthane framework and myrcene. Pleiades Publishing, Ltd., 2012.
- Anikeev,Il'Ina,Volcho,Salakhutdinov
-
p. 1917 - 1919
(2013/01/15)
-
- The oxidation of pyridine and alcohol using the Keggin-type lacunary polytungstophosphate as a temperature-controlled phase transfer catalyst
-
A novel temperature-controlled phase transfer catalyst of [(C 18H37)2(CH3)2N] 7[PW11O39] has been developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were conducted in 1,4-dioxane, and high yields of the corresponding heterocyclic N-oxides and ketones were obtained under relative mild conditions. The catalyst could be easily recovered and reused after reaction with cooling. There was no discernable loss in activity and selectivity after several reaction cycles.
- Ding, Yong,Zhao, Wei
-
experimental part
p. 45 - 51
(2011/04/24)
-
- Menthone aryl acid hydrazones: A new class of anticonvulsants
-
A series of ten compounds (Compounds J1-J10) of (±) 3-menthone aryl acid hydrazone was synthesized and characterized by thin layer chromatography and spectral analysis. Synthesized compounds were evaluated for anticonvulsant activity after intraperitoneal (i.p) administration to mice by maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure method and minimal clonic seizure test. Minimal motor impairment was also determined for these compounds. Results obtained showed that four compounds out of ten afforded significant protection in the minimal clonic seizure screen at 6 Hz. Compound J6, 4-Chloro-N-(2-isopropyl-5- methylcyclohexylidene) benzohydrazide was found to be the most active compound with MES ED50 of 16.1 mg/kg and protective index (pI) of greater than 20, indicating that (±) 3-menthone aryl acid hydrazone possesses better and safer anticonvulsant properties than other reported menthone derivatives viz. menthone Schiff bases, menthone semicarbazides and thiosemicarbazides.
- Jain, Jainendra,Kumar,Sinha, Reema,Kumar, Rajeev,Stables, James
-
experimental part
p. 56 - 61
(2012/01/11)
-
- Menthone semicarbazides and thiosemicarbazides as anticonvulsant agents
-
A series of novel (±) 3-menthone semicarbazides (1-7) and thiosemicarbazides (8-14) were synthesized using an appropriate synthetic route and characterized by thin layer chromatography and spectral analysis. The anticonvulsant activity of synthesized compounds was established after intraperitoneal administration in three seizure models in mice which include maximal electroshock seizure (MES), subcutaneous pentylene tetrazole (scPTZ) induced seizure and minimal neurotoxicity test. Seven compounds exhibited protection in both models and N1 - (4-fluorophenyl) - N4- (menth-3-one) semicarbazide (4) emerged as the most active compound with MES ED50 of 44.15mg/kg and scPTZ ED50 of 38.68mg/kg at 0.25h duration. These compounds were found to elevate γ-amino butyric acid (GABA) levels in the midbrain region, thus indicating that (±) 3-menthone semicarbazides could be considered as a lead molecule in designing of a potent anticonvulsant drug.
- Jain, Endra,Kumar,Stables, James,Sinha, Reema
-
experimental part
p. 44 - 50
(2011/11/12)
-
- Heteropoly acid-based supported ionic liquid-phase catalyst for the selective oxidation of alcohols
-
A supported ionic liquid strategy has been applied for the immobilization of a heteropolyacid, molybdovanadophosphoric acid, onto ionic liquid-modified mesoporous silica SBA-15. The immobilized catalyst demonstrated high activity in the aerobic oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. No overoxidation of the primary alcohols to carboxylic acids was observed. Secondary alcohols were chemoselectively oxidized to ketones in the presence of primary alcohol, hetero atom, and allyl groups. This catalyst could be recycled five times without obvious loss of activity.
- Bordoloi, Ankur,Sahoo, Suman,Lefebvre,Halligudi
-
experimental part
p. 232 - 239
(2009/03/11)
-
- Conjugate reduction of α,β-unsaturated carbonyl compounds promoted by nickel nanoparticles
-
The system composed of nickel(II) chloride, lithium metal, a catalytic polymer-supported arene, and ethanol, has been efficiently applied to the conjugate reduction of a variety of α,β-unsaturated carbonyl compounds (ketones and carboxylic acid derivatives) under very mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Alonso, Francisco,Osante, I?aki,Yus, Miguel
-
p. 3017 - 3020
(2008/02/12)
-
- Insight into the mechanism of oxidative kinetic resolution of racemic secondary alcohols by using manganese(III)(salen) complexes as catalysts
-
The oxidative kinetic resolution of various racemic secondary alcohols with PhI(OAc)2 catalyzed by chiral [MnIII(salen)] complexes in the presence of KBr was studied in a water/organic solvent mixture. The dramatic, synergetic effect of additives, organic solvent, and the substituents of chiral salen ligands on the enantioselectivities of the reactions is reported. Results from UV/Vis spectroscopy and ESI-MS studies provide evidence that these reactions are induced by the formation of a high-valent manganese intermediate.
- Li, Zhen,Tang, Zhong H.,Hu, Xiao X.,Xia, Chun G.
-
p. 1210 - 1216
(2007/10/03)
-
- Thiol-catalyzed acyl radical cyclization of alkenals
-
(Chemical Equation Presented) Thiol-catalyzed direct generation of acyl radicals and their intramolecular addition to olefins of alkenals gave 2-substituted five- and six-membered cyclic ketones in reasonably good yields. The combination of odorless tert-dodecanthiol and AIBN or V-40 was the initiator of choice among surveyed radical generators for the cyclization of alkenals. Aldehydes having electron-deficient olefins cyclized more easily than those having unactivated olefins.
- Yoshikai, Kazuya,Hayama, Tomoharu,Nishimura, Katsumi,Yamada, Ken-Ichi,Tomioka, Kiyoshi
-
p. 681 - 683
(2007/10/03)
-
- Novel Vanadium-Catalyzed Oxidation of Alcohols to Aldehydes and Ketones under Atmospheric Oxygen
-
(Matrix presented) Oxidation of alcohols to aldehydes and ketones has been studied in high yields using atmospheric oxygen and a catalytic amount of V 2O5 in toluene under heating (ca. 100°C). Secondary alcohols can be chemoselectively converted into ketones in the presence of primary hydroxy groups.
- Velusamy, Subbarayan,Punniyamurthy
-
p. 217 - 219
(2007/10/03)
-
- Novel polyaniline-supported molybdenum-catalyzed aerobic oxidation of alcohols to aldehydes and ketones
-
(Chemical Equation Presented) Oxidation of alcohols to aldehydes and ketones has been studied in high yields using molecular oxygen and a catalytic amount of 1 in toluene under stirring (ca. 100°C). The reactions of primary alcohols are faster compared to secondary alcohols and the catalyst 1 can be recycled without loss of activity.
- Velusamy, Subbarayan,Ahamed, Muneer,Punniyamurthy
-
p. 4821 - 4824
(2007/10/03)
-
- The Dual Roles of Oxodiperoxovanadate Both as a Nucleophile and an Oxidant in the Green Oxidation of Benzyl Alcohols or Benzyl Halides to Aldehydes and Ketones
-
One catalyst, two roles: VO(O2)2- reacts as a nucleophilic oxidant under acidic conditions towards benzyl alcohols. Altogether 15 alcohols have been oxidized, in the absence of organic solvent, in excellent yields. Benzyl halides are also oxidized by H2O 2 in water catalyzed by oxodiperoxovanadate and a phase transfer catalyst into aromatic aldehydes and ketones (see scheme). This reaction is the first green oxidation of benzyl halides.
- Li, Chunbao,Zheng, Pengwu,Li, Jie,Zhang, Hang,Cui, Yi,Shao, Qiyun,Ji, Xiujie,Zhang, Jian,Zhao, Pengying,Xu, Yanli
-
p. 5063 - 5066
(2007/10/03)
-
- Oxidation of alcohols using cerium(IV) alkyl phosphonate modified silica
-
The oxidation of a range of alcohols to ketones or carboxylic acids proceeds in good yield using catalytic quantities of cerium(IV) phosphonate modified silica and sodium bromate as the re-oxidant.
- Al-Haq, Nazli,Sullivan, Alice C.,Wilson, John R. H.
-
p. 769 - 771
(2007/10/03)
-
- Highly sustainable catalytic dehydrogenation of alcohols with evolution of hydrogen gas
-
The catalytic dehydrogenation of alcohols into aldehydes and ketones in the absence of H-acceptors was studied with several transition metal catalysts in order to develop a large-scale procedure. Applying Ru(OCOCF3)2(CO)(PPh3)2, the so called Robinson catalyst, several secondary alcohols could be dehydrogenated with high selectivity into the corresponding ketones in relatively short reaction times. Highly effective atom utilization could be realized avoiding solvents and giving hydrogen gas as the sole by-product. However, in contrast to Robinson's work the catalytic dehydrogenation of primary alcohols appeared to be problematic due to decarbonylation with concomitant catalyst deactivation and aldol condensation under the strong acid or basic conditions applied.
- Ligthart,Meijer,Donners,Meuldijk,Vekemans,Hulshof
-
p. 1507 - 1509
(2007/10/03)
-
- Catalytic oxidation of alcohols with allyl diethyl phosphate and palladium acetate
-
Allyl diethyl phosphate (ADP) was found to function as a stoichiometric hydrogen acceptor in a catalytic oxidation reaction of alcohols with Pd(OAc)2. A variety of acyclic primary and secondary alcohols were oxidized in good yields and under mild conditions to the corresponding aldehydes and ketones, in the presence of Na2CO3 or K2CO3. Simple aliphatic primary alcohols yielded esters, exclusively. Polar ligand solvents (DMF, DMSO) were found to accelerate the reaction. Slow, but high yield reactions were encountered in THF and acetonitrile as solvents. The reactivity of several other allyl systems serving as H-acceptors, and several Pd compounds serving as catalysts, in the above oxidation reaction, was evaluated. It has been experimentally demonstrated (H-NMR) that ADP is capable of generating a π-allyl-Pd complex using a Pd(0) complex. Consequently, a catalytic cycle was proposed for the above oxidation reaction.
- Shvo, Youval,Goldman-Lev, Vered
-
p. 151 - 156
(2007/10/03)
-
- Silica gel supported jones reagent (SJR): A simple, versatile, and efficient reagent for oxidation of alcohols in non-aqueous media
-
Oxidation of alcohols to carbonyl compounds has been carried out by utilization of Jones reagent supported on silica gel (SJR). The SJR procedure has advantages over traditional Jones oxidation procedure. This procedure is safer to carry out and simplified workup by allowing organic media.
- Ali,Wiggin
-
p. 3383 - 3393
(2007/10/03)
-
- Polymer-supported N-methylmorpholine N-oxide as an efficient and readily recyclable co-oxidant in the TPAP oxidation of alcohols
-
A readily available, polymer supported amine N-oxide has been prepared and shown to be a practicable, efficient, selective, and readily recyclable co-oxidant in the TPAP oxidation of alcohols.
- Brown,Kerr,Lindsay,Pike,Ratcliffe
-
p. 1257 - 1259
(2007/10/03)
-
- Chemoselective C-H oxidation of alcohols to carbonyl compounds with iodosobenzene catalyzed by (Salen)chromium complex
-
Primary and secondary alcohols with benzylically and allylically activated C-H bonds are chemoselectively oxidized to the corresponding carbonyl compounds by the (salen)Cr(III) complex I as the catalyst and iodosobenzene as the oxygen source; the oxidizing species is the Cr(V) oxo complex. Allylic alcohols with fully substituted double bonds give appreciable amounts of epoxides besides the C-H oxidation products enones, while saturated alcohols are less readily oxidized.
- Adam, Waldemar,Gelalcha, Feyissa Gadissa,Saha-Moeller, Chantu R.,Stegmann, Veit R.
-
p. 1915 - 1918
(2007/10/03)
-
- Microwave-assisted oxidation of alcohols using wet alumina supported ammonium chlorochromate in solventless system
-
A simple and selective method for the oxidation of alcohols to carbonyl compounds is described that occurs on wet alumina supported ammonium chlorochromate under microwave irradiation in solventless system.
- Heravi, Majid M.,Aghayan, Maryam M.
-
p. 815 - 817
(2007/10/03)
-
- The synthesis of menthone by ozonization of menthol
-
A selective method of oxidation of menthol to menthone by Co(OAc)2-catalyzed ozonization in ethyl acetate or Freon-113 was developed.
- Odinokov,Botsman,Emel'yanova
-
p. 2021 - 2022
(2007/10/03)
-
- Biotransformations of racemic acetates by potato and topinambur tubers
-
The hydrolysis of acetates: (±)-1-phenylethyl ((±)-1), (±)-1-(1- naphthyl)ethyl ((±)-2), (±)-1-(naphthyl)ethyl ((±)-3) and (±)-menthyl ((±)-4) with the use of potato and topinambur (artichoke) tubers results in the production of alcohols, which in the same environment are oxygenated to ketones. Pure S-1-phenylethyl acetate has been produced.
- Mironowicz, Agnieszka
-
p. 1531 - 1534
(2007/10/03)
-
- Oxidative deprotection of allyl glycosides
-
Allyl glycosides can be deprotected under the condition of the Kharasch- Sosnovsky reaction and by photoinduced reaction with di-(t)butylperoxide in the presence of bromotrichloromethane.
- Kraehmer, Ralf,Hennig, Lothar,Findeisen, Matthias,Mueller, Dietrich,Welzel, Peter
-
p. 10753 - 10760
(2007/10/03)
-
- Cu/SiO2: An improved catalyst for the chemoselective hydrogenation of α,β-unsaturated ketones
-
Cu/SiO2 can be conveniently used for the quantitative hydrogenation of conjugated enones to saturated ketones, also when another olefinic bond is present in the molecule, under very mild conditions. Molecular H2 or 2-propanol can be used as hydrogen source.
- Ravasio, Nicoletta,Antenori, Marisa,Gargano, Michele,Mastrorilli, Piero
-
p. 3529 - 3532
(2007/10/03)
-
- Transition-metal catalyzed oxidations. 7. Zirconium-catalyzed oxidation of primary and secondary alcohols with hydroperoxides
-
A new procedure for the oxidation (dehydrogenation) of primary and secondary alcohols employing Zr(O-t-Bu)4 or Zr(O-n-Pr)4/tert-butyl hydroperoxide/3 A molecular sieves is presented. Secondary alcohols - if not severely sterically hindered - are usually converted quantitatively to the corresponding ketones. Esters or acids can be by products in the reaction of primary alcohols. However, the aldehydes are obtained in good yield by lowering the reaction temperature, decreasing the amount of TBHP or replacing TBHP by cumene hydroperoxide (CHP), and/or exchanging the catalyst Zr(O-t-Bu)4 by Zr(O-n-Pr)4 or silica gel-supported Zr(OR)(x). A remarkable selectivity of equatorial alcohol groups (e.g., 11 and 13) is observed in contrast to chromium(VI)-based oxidations. Strongly chelating substrates such as furfuryl alcohol (18) or 1,2-diol 25 that prevent hydride transfer in the six-membered transition state A are not converted.
- Krohn, Karsten,Vinke, Ingeborg,Adam, Horst
-
p. 1467 - 1472
(2007/10/03)
-
- Oxidation by Polychromates
-
The oligomeric chromates, potassium trichromate, K2Cr3O10, (K3C), and potassium tetrachromate K2Cr4O13, (K4C), are soluble in solvents such as acetone, acetonitrile, ethyl acetate, DMF and THF. Solutions of K3C or K4C in acetonitrile readily oxidized alcohols to the corresponding aldehydes or ketones in moderate to good yields.
- Carlsen, P. H. J.,Kjaerstad, Cathrine,Aasboe, Kari
-
p. 152 - 154
(2007/10/02)
-
- A Novel Hexanuclear Heteropolyperoxo Oxidation Catalyst: Preparation, X-Ray Crystal Structure and Reactions of 3W6O13(O2)4(OH)2(OH2)>*4H2O
-
The crystal structure of the title compound, 1, reveals the presence of two distinct types of tungsten atom in which the four bearing peroxo groups have distorted pentagonal-bipyramidal geometries and the remaining two are octahedral; 1 is an effective catalyst for monoalkene epoxidation, and the oxidation of primary and secondary alcohols, with H2O2 as co-oxidant.
- Griffith, William P.,Parkin, Bernardeta C.,White, Andrew J. P.,Williams, David J.
-
p. 2183 - 2184
(2007/10/02)
-
- The Crystal Structures of 22> and 2 and Their Use as Catalytic Oxidants
-
The new trinuclear heteropolyperoxo complexes 22> (R = Ph, M = Mo 1 or W 2) have been isolated and the crystal structure of the molybdenum complex is reported.A series of analogous molybdenum complexes (R = Me, Et, n-Bu, or t-Bu; M = Mo) have also been synthesised and characterised.The use of these compounds as catalysts for the epoxidation of alkenes, oxidation of alcohols and of tertiary amines with hydrogen peroxide as cooxidant has been studied, and complex 2 is shown to be particularly effective for such oxidations.The crystal structure of the new tetranuclear isopolyperoxo species 2 3 is also reported and its properties as a catalyst for alkene epoxidation with hydrogen peroxide as cooxidant studied.
- Griffith, William P.,Parkin, Bernadeta C.,White, Andrew J. P.,Williams, David J.
-
p. 3131 - 3138
(2007/10/03)
-
- Oxo Complexes of Ruthenium with N,N'-Donors as Oxidation Catalysts for Alkenes, Alkanes and Alcohols, and their Osmium Analogues
-
Catalysis of the epoxidation of alkenes and oxidation of alkanes and alcohols by a variety of bis-bipy (2,2'-bipyridyl) and bis-phen (1,10-phenanthroline) ruthenium complexes with NaIO4 or IO4 as co-oxidants has been investigated together with similar oxidations with >*1.5H2O.The new complexes > and > (L-L = bipy, phen or 2,2'-dipyridylamine) have been prepared and characterised.
- Bailey, Alan J.,Griffith, William P.,Savage, Paul D.
-
p. 3537 - 3542
(2007/10/03)
-
- Cobalt catalyzed oxidation of secondary alcohols with dioxygen in the presence of 2-methylpropanal
-
Cobalt schiff base complex 2 catalyses the oxidation of a wide range of secondary alcohols to the corresponding ketones in the presence of dioxygen and 2-methylpropanal.
- Kalra, Swinder Jeet Singh,Punniyamurthy,Iqbal, Javed
-
p. 4847 - 4850
(2007/10/02)
-
- A New Epoxidation Catalyst: the Reactivity and X-Ray Crystal Structure of >*1.5H2O (bipy = 2,2'-bipyridine)
-
The crystal structure of >*1.5H2O 1 is reported: with NaIO4 or NBun4IO4 as cooxidant it is an efficient catalyst for alkene epoxidations under mild conditions; it also oxidises primary alcohols to aldehydes and secondary alcohols to ketones.
- Bailey, Alan J.,Griffith, William P.,White, Andrew J. P.,Williams, David J.
-
p. 1833 - 1834
(2007/10/02)
-
- Studies on Polyoxo- and Polyperoxo-metalates. Part 1. Tetrameric Heteropolyperoxotungstates and Heteropolyperoxomolybdates
-
New heteropolyperoxometalates of the type R34> (3+) (en = ethane-1,2-diamine); X = P or As; M = Mo or W> have been characterized by IR, Raman and where appropriate 31P NMR spectroscopy.Epoxidation of cyclic and linear alkenes by these species with H2O2 as co-oxidant has been studied; 4>(3-) was found to be the most effective.The oxidation of alcohols by 4>(3-) with H2O2 has been investigated.
- Dengel, Andrew C.,Griffith, William P.,Parkin, Bernardeta C.
-
p. 2683 - 2688
(2007/10/02)
-
- Acyl Radicals: Intermolecular and Intramolecular Alkene Addition Reactions
-
A full study of the use of phenyl selenoesters as precursors to acyl radicals and their subsequent participation in intermolecular and intramolecular alkene addition reactions is detailed.Primary alkyl-, vinyl-, and arylsubstituted acyl radicals generated by Bu3SnH treatment of the corresponding phenyl selenoesters participate cleanly in intermolecular addition reactions with alkenes bearing electron-withdrawing or radical-stabilizing substituents at rates that exceed those of the potentially competitive decarbonylation or reduction.Similarly, their intramolecular addition to activated or unactivated alkenes proceeds without significant competitive reduction or decarbonylation and at rates generally >/= 1 x 106 s-1 with some occuring at rates >/= 3 x 107 s-1.Consistent with their behavior in intermolecular addition reactions, the 5-exo-trig cyclizations of secondary and tertiary alkyl-substituted acyl radicals to an unactivated olefin acceptor may be accompanied by varying degrees of decarbonylation, even under low-temperature free-radical conditions.Studies are presented which suggest that the intramolecular additions of acyl radicals to alkenes under the conditions detailed herein may be regarded as irreversible, kinetically controlled processes which exhibit regioselectivity that is predictable based on well-established empirical rules set forth for the analogous free-radical cyclization reactions of alkyl radicals.
- Boger, Dale L.,Mathvink, Robert J.
-
p. 1429 - 1443
(2007/10/02)
-
- Synthesis of Bis(pyridodipyrimidines) as Autorecycling Redox Catalysts and Their Remarkable Turnover in the Oxidation of Alcohols
-
Bis(pyridodipyrimidines) (bis-PP's) as redox catalysts, in which two pyridodipyrimidine moieties are linked with polymethylene chains, have been synthesised by the condensation of bis(6-chloro-5-formyluracil-3-yl)alkanes with 6-alkylaminouracils.These bis-PP's oxidized alcohols more efficiently than monomeric pyridodipyrimidines to give the corresponding carbonyl compounds.Particularly, bis(7-methyl-10-(n-octyl)pyridodipyrimidin-3-yl)decane (5j) exhibitet remarkable oxidizing ability toward cyclopentanol as a turnover catalyst, and its maximum effective concentration(MEC) was determined.The MEC of 5j was 6.7E-5 mmol (59 μg)/3 ml of cyclopentanol at 115 deg C, and the MEC under introduction of oxygen (5 ml of oxygen/min) was 2E-4 mmol (177 μg)/3 ml of cyclopentanol at 100 deg C.Apart from the chemical yield of cyclopentanone, even an amount of only 2E-11 mmol (17.7 pg) of catalyst 5j oxidized cyclopentanol to give cyclopentanone in 13300000000000 percent yield based on the catalyst.This implies that the turnover number of catalyst 5j is 8.9E7 mol min-1 (mol of catalyst)-1, which would surpass that of bovine liver catalase, although the condition is quite different.
- Yoneda, Fumio,Tanaka, Kiyoshi,Yamato, Hirotake,Moriyama, Kenji,Nagamatsu, Tomohisa
-
p. 9199 - 9202
(2007/10/02)
-
- HOMOLYTIC CYCLIZATION OF SELENOL ESTERS. SYNTHESIS OF CHROMANONES
-
Acyl radicals produced by tributyltin hydride-azobisisobutyronitrile induced homolysis of phenylselenol esters undergo highly selective 6-exo-trig addition to double bonds, affording, in a chain reaction, cyclic oxo-compounds in very high yield.Suitably substituted phenylselenosalicylates are thus converted into the corresponding chromanes.
- Bachi, Mario D.,Denenmark, Daniella
-
p. 583 - 588
(2007/10/02)
-
- Stereochemical Aspects in the Insertion by Alkylidenemethylene Carbenoids into the α-C-H Bond of Alkoxides
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Primary alkoxides (R1CH2OM; M=K or Li) when treated with haloalkenes (R3R4C=CXY; X=Cl or Br, Y=H or Cl) in the presence of n-BuLi in THF at 0 deg C gave allylic alcohols (R1CH(OH)CH=CR3R4) through the insertion reaction of the corresponding alkylidenemethylene carbenoid () into the α-C-H bond of alkoxides.Secondary alkoxides (R1R2CHOM), under similar reaction conditions, gave butyl adducts (R1R2C(OH)C4H9) in addition to the insertion products.In particular, the C-H insertion of menthyl oxide proceeded without stereospecificity to give a mixture of the axial and equatorial insertion products.These results provided evidence for the hydride abstraction-recombination mechanism in the carbenoid insertion reaction.The regioselective, nonstereospecific insertion reaction was also observed when alkoxides were treated with separately prepared ((2,3-benzo-2-cyclohexylidene)chloromethyl)lithium at temperatures from -95 to -40 deg C.The absence of H-D scrambling in crossover experiments under these reaction conditions clearly showed that the hydride abstraction-recombination mechanism proceeded within a solvent cage.An inversion of configuration on the carbenoid carbon in the hydride abstraction step was proposed on the basis of the E/Z stereoselectivity in the insertion products.
- Oku, Akira,Harada, Toshiro,Hattori, Kazuhiro,Nozaki, Yohko,Yamaura, Yasunari
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p. 3089 - 3098
(2007/10/02)
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- Structure-Odor Correlation, V. - From Menthone to Shyobunone - Change of Odor with Structure
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Derivatives of menthone (4) were prepared by substitution at C-2 or C-3 whereby increasing similarity with the shyobunones (1, 2) should be achieved.Thus, the 3,3-disubstituted ketones 5-11 were synthesized by 1,4-addition to piperitone(3).The ketones 18 and 19 substituted at C-2 were prepared via the silyl ether 15.Analogously the ketones 22-25 have been synthesized.The ketones 28 and 29 were obtained from 15 via the diketone 20 and the aldol 21. - Key compound for the synthesis of 43 and 44 as well as 1 and 2 by 1,4-addition was the known ketone 40.While preparing 40 the side products 41 and 42 have also been obtained.The olfactory properties of the substituted menthones change stepwise from the minty odor of 4 by addition of spicy and woody notes up to those of 1 and 2 which possess a fruity-earthy-woody odor.
- Weyerstahl, Peter,Rilk, Reiner,Marschall-Weyerstahl, Helga
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- Highly Chemoselective Palladium-Catalyzed Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds with Silicon Hydrides and Zinc Chloride Cocatalyst
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A three-component system comparised of a soluble palladium catalyst, hydridosilane, and zinc chloride is capable of efficient conjugate reduction of α,β-unsaturated ketones and aldehydes.The optimal set of condition includes diphenylsilane as the most effective hydride donor, any soluble palladium complex in either the 0 or II oxidation state, when it is stabilized by phosphine ligands, and ZnCl2 as the best Lewis acid cocatalyst.The reaction is very general with respect to a broad range of unsaturated ketones and aldehydes, and it is highly selective for these Michael acceptors, as reduction of α,β-unsaturated carboxylic acid derivatives is very sluggish under these conditions.When dideuteriodiphenylsilane is used to reduce unsaturated ketones, deuterium is stereoselectively introduced at the less-hindered face of the substrate and regioselectively at the β-position.Conversely, when reductions are carried out in the presence of traces of D2O, deuterium incorporation occurs at the α-position.On the basis of deuterium-incorporation experiments and 1H NMR studies, a catalytic cycle is postulated in which the first step involves reversible coordination of the palladium complex to the electron-deficient olefin and oxidative addition of silicon hydride to form a hydropalladium olefin complex.Migratory insertion of hydride into the coordinated olefin produces an intermediate palladium enolate which, via reductive elimination, collapses back to the Pd(0) complex and a silyl enol ether, which is then hydrolyzed to the saturated ketone.In addition to catalyzing that hydrolysis, ZnCl2 facilitates the hydrosilation process.
- Keinan, Ehud,Greenspoon, Noam
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p. 7314 - 7325
(2007/10/02)
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- 3-CARBOXYPYRIDINIUM DICHROMATE (NDC) AND 4-CARBOXYPYRIDINIUM DICHROMATE (INDC). TWO NEW MILD, STABLE, EFFICIENT AND INEXPENSIVE CHROMIUM (VI) OXIDATION REAGENTS
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Two mild new chromium (VI) reagents derived from nicotinic acid and isonicotinic acid are described.Nicotinium dichromate (NDC) and isonicotinium dichromate (INDC) oxidize alcohols into carbonyl compounds, mercaptanes into disulfides and hydroquinones into quinones.Oxidation of polynuclear aromatic hydrocarbons is made.Pyridine assisted oxidations by means of these reagents are also described.
- Lopez, C.,Gonzalez, A.,Cossio, F. P.,Palomo, C.
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p. 1197 - 1212
(2007/10/02)
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- EXCLUSIVE 1-4 REDUCTION OF CONJUGATED KETONES BY SODIUM DITHIONITE
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α-β unsaturated aldehyde and ketones were exclusively reduced to the corresponding saturated aldehyde and ketones by the use of sodium dithionite under phase- transfer catalysis conditions.Neither allylic nor saturated alcohols are formed.
- Louis-Andre, O.,Gelbard, G.
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p. 831 - 832
(2007/10/02)
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- PHOTOCHEMICAL TRANSFORMATIONS-IV. OXYFUNCTIONALIZATION OF SOME SATURATED HYDROCARBONS WITH HYDROXYL RADICALS
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It is shown that hydroxylation of saturated hydrocarbons by hydrogen peroxide occurs under the influence of light.This reaction has been investigated on acyclic, monocyclic and bicyclic hydrocarbons.These reactions were also studied using performic acid as the source of hydroxyl radicals and results compared with those obtained with peracetic acid.As expected, the preferred attack was on tertiary centres, followed by secondary and then primary.
- Sharma, S. N.,Sonawane, H. R.,Dev, Sukh
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p. 2483 - 2492
(2007/10/02)
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- FACILE HOMOGENEOUS HYDROGENATIONS OF HINDERED OLEFINS WITH PF6
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The title complex readily hydrogenates a number of hindered steroidal olefin groups from the α face, without reducing ketone carbonyl groups, carbon-halogen bonds or cyclopropane rings.
- Suggs, J. William,Cox. S. D.,Crabtree, Robert H.,Quirk, Jennifer M.
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p. 303 - 306
(2007/10/02)
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