cas 100-86-7, 2-Methyl-1-phenyl-2-propanol

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Reactivity of a Palladacyclic Complex: A Monodentate Carbonate Complex and the Remarkable Selectivity and Mechanism of a Neophyl Rearrangement
The ligand N(CH2-2-C5H4N)2(CH2CH2CH2OH), L1, reacted with [Pd(CH2CMe2C6H4)(COD)] to give a new fluxional cycloneophyl organopalladium complex [Pd(CH2CMe2C6H4)(κ2-L1)], 1, which on attempted recrystallization from THF gave the monodentate carbonate complex [Pd(CO3)(κ3-L1)], 2. Complex 2 was prepared in designed syntheses by reaction of [PdCl(κ3-L1)]+ with silver carbonate or by reaction of [Pd(OH)(κ3-L1)]+ with CO2. Complex 1 reacted with aqueous CO2 to give the cationic neophylpalladium complex [Pd(CH2CMe2C6H5)(κ3-L1)]+(HCO3)-, 6. Complex 6 reacts with hydrogen peroxide to give complex 2 with release of a mixture of organic products, the major one being 2-phenyl-2-butanol, PB. The formation of PB involves a neophyl rearrangement with the unprecedented preference for methyl over phenyl migration. A mechanistic basis for this unexpected reaction is proposed, involving β-carbon elimination at a palladium(IV) center.
Behnia, Ava,Fard, Mahmood A.,Blacquiere, Johanna M.,Puddephatt, Richard J.
p. 4759 - 4769
(2017)
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Heterolytic cleavage of peroxide by a diferrous compound generates metal-based intermediates identical to those observed with reactions utilizing oxygen-atom-donor molecules
Under cryogenic stoppedflow conditions, addition of 2-methyl-lphenylprop-2- yl hydroperoxide (MPPH) to the diiron(II) compound, [Fe2(H 2Hbamb)2(NMeIm)2] (1; NMeIm = /V-methylimidazole; H4HBamb: 2,3-bis(2-hydroxybenzamido) dimethylbutane) results in heterolytic peroxide ○-○ bond cleavage, forming a highvalent species, 2. The UV/Vis spectrum of 2 and its kinetic behavior suggest parallel reactivity to that seen in the reaction of 1 with oxygen-atom-donor (OAD) molecules, which has been reported previously. Like the interaction with OAD molecules, the reaction of 1 with MPPH proceeds through a three step process, assigned to oxygen-atom transfer to the iron center to form a high-valent intermediate (2), ligand rearrangement of the metal complex, and, finally, decay to a diferric μ-oxo compound. Careful examination of the order of the reaction with MPPH reveals saturation behavior. This, coupled with the anomalous non-Arrhenius behavior of the first step of the reaction, indicates that there is a preequilibrium peroxide binding step prior to ○-○ bond cleavage. At higher temperatures, the addition of the base, proton sponge, results in a marked decrease in the rate of ○-○ bond cleavage to form 2; this is assigned as a peroxide deprotonation effect, indicating that the presence of protons is an important factor in the heterolytic cleavage of peroxide. This phenomenon has been observed in other iron-containing enzymes, the catalytic cycles of which include peroxide O-O bond cleavage.
Rowe, Gerard T.,Rybak-Akimova, Elena V.,Caradonna, John P.
p. 8303 - 8311
(2008)
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Tiffeneau,Delange
p. 575
(1903)
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Cyclobutylcarbinyl p-Bromobenzenesulfonate Solvolysis. A Stady of Response to Solvent Ionizing Strength
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Roberts, Donald D.
p. 561 - 564
(1982)
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Catalytic Replacement of Unactivated Alkane Carbon-Hydrogen Bonds with Carbon-X Bonds (X = Nitrogen, Oxygen, Chlorine, Bromine, or Iodine). Coupling of Intermolecular Hydrocarbon Activation by MnIIITPPX Complexes with Phase-Transfer Catalysis
A simple system has been devised to facilitate the first processes for the catalytic replacement of unactivated alkane C-H bonds with C-X bonds, X = nitrogen and iodine.The system also enables alkane C-H bonds to be replaced by C-X bonds, X = chlorine, bromine, and oxygen.The system is composed of two liquid phases and the oxidant iodosylbenzene (iodosobenzene).The alkane substrate, the MnIIITPPX catalyst, and the organic solvent (dichloromethane, chlorobenzene, or other aromatic hydrocarbon) constitute one phase, a saturated aqueous solution of the sodium salt of the anion to be incorporated into the alkane, NaX, X = N3(1-), NCO(1-), I(1-), Br(1-), or Cl(1-), constitutes the second phase, and the sparingly soluble oxidant iodosylbenzene constitutes a third phase.When the two liquid phases and the oxidant iodosylbenzene are stirred under an inert atmosphere, both RX and ROH products are produced catalytically based on MnTPP and in reasonable yield based on iodosylbenzene.The MnTPP moiety functions as a catalyst for C-H bond cleavage and for phase transfer of X(1-) from the aqueous phase to the organic phase where the functionalization chemistry takes place.The oxidant hypochlorite can be used in place of, but is less effective than, iodosylbenzene, and the oxidants hydrogen peroxide, periodate, and persulfate are ineffective.Product distributions obtained from the oxidation of cyclohexane, isobutane, 2,3-dimethylbutane, and tert-butylbenzene are most consistent with a product-determining step that involves transfer of X from manganese to a free alkyl radical intermediate.
Hill, Craig L.,Smegal, John A.,Henly, Timothy J.
p. 3277 - 3281
(1983)
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Tuning the selectivity in the aerobic oxidation of cumene catalyzed by nitrogen-doped carbon nanotubes
In this study it is demonstrated that carbon nanotubes (CNTs) with doped nitrogen atoms in graphitic domains (NCNTs) can act as a new class of metal-free catalysts exhibiting excellent activity in the aerobic oxidation of cumene. We proved that NCNTs can promote the decomposition of hydroperoxide cumene with exceptionally high activity, resulting in strongly increased cumene conversion and extraordinarily high selectivity to acetophenone and 2-benzyl-2-propanol. The incorporation of nitrogen altered the surface electron structure of the CNTs and tuned the reactivity and selectivity. DFT calculations revealed that the remarkable improvement of catalytic performance of NCNTs is caused by the strong interaction between hydroperoxide cumene and the NCNTs. NCNTs also exhibited desirable recyclability after four cycling tests. This study not only provides a novel method for the cumene oxidation to high-value-added products at moderate reaction temperatures and oxygen atmospheric pressure, but also gives new insights into the effect of surface nitrogen doping on carbon-catalyzed liquid-phase oxidation of aromatic hydrocarbons. b Copyright
Liao, Shixia,Chi, Yumei,Yu, Hao,Wang, Hongjuan,Peng, Feng
p. 555 - 560
(2014)
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Use of Sacrificial Anodes in Electrochemical Functionalization of Organic Halides
This article reviews the new possibilities in organic synthesis offered by the electroreduction of organic halides in the presence of various electrophiles using sacrificial metallic anodes.
Chaussard, Jacques,Folest, Jean-Claude,Nedelec, Jean-Yves,Perichon, Jacques,Sibille, Soline,Troupel, Michel
p. 369 - 381
(1990)
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Mechanistic Insights into Fe Catalyzed α-C?H Oxidations of Tertiary Amines
We report detailed mechanistic investigations of an iron-based catalyst system, which allows the α-C?H oxidation of a wide variety of amines. In contrast to other catalysts that effect α-C?H oxidations of tertiary amines, the system under investigation exclusively employs peroxy esters as oxidants. More common oxidants (e. g. tBuOOH) previously reported to affect amine oxidations via free radical pathways do not provide amine α-C?H oxidation products in combination with the described catalyst system. The investigations described herein employ initial rate kinetics, kinetic profiling, DFT calculations as well as Eyring, kinetic isotope effect, Hammett, ligand coordination, and EPR studies to shed light on the Fe catalyst system. The obtained data suggest that the catalytic mechanism proceeds through C?H abstraction at a coordinated substrate molecule. This rate-determining step occurs either through an Fe(IV) oxo pathway or a 2-electron pathway at an Fe(II) intermediate with bound oxidant. DFT calculations indicate that the Fe(IV) oxo mechanism will be the preferred route of these two possibilities. We further show via kinetic profiling and EPR studies that catalyst activation follows a radical pathway, which is initiated by hydrolysis of PhCO3tBu to tBuOOH. Overall, the obtained mechanistic data support a non-classical, Fe catalyzed pathway that requires substrate binding, inducing selectivity for α-C?H functionalization.
Legacy, Christopher J.,Hope, Taylor O.,Gagné, Yohann,Greenaway, Frederick T.,Frenette, Mathieu,Emmert, Marion H.
p. 235 - 246
(2021)
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Model dialkyl peroxides of the fenton mechanistic probe 2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH): Kinetic probes for dissociative electron transfer
Two dialkyl peroxides, devised as kinetic probes for the heterogeneous electron transfer (ET), are studied using heterogeneous and homogeneous electrochemical techniques. The peroxides react by concerted dissociative ET reduction of the O-O bond. Under heterogeneous conditions, the only products isolated are the corresponding alcohols from a two-electron reduction as has been observed with other dialkyl peroxides studied to date. However, under homogeneous conditions, a generated alkoxyl radical undergoes a rapid β-scission fragmentation in competition with the second ET resulting in formation of acetone and a benzyl radical. With knowledge of the rate constant for fragmentation and accounting for the diffuse double layer at the electrode interface, the heterogeneous ET rate constant to the alkoxyl radicals is estimated to be 1500 cm s-1. The heterogeneous and homogeneous ET kinetics of the O-O bond cleavage have also been measured and examined as a function of the driving force for ET, ΔGET, using dissociative electron transfer theory. From both sets of kinetics, besides the evaluation of thermochemical parameters, it is demonstrated that the heterogeneous and homogeneous reduction of the O-O bond appears to be non-adiabatic.
Magri, David C.,Workentin, Mark S.
p. 3418 - 3429
(2003)
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Singh
p. 714
(1971)
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Visible-Light-Driven Palladium-Catalyzed Radical Alkylation of C?H Bonds with Unactivated Alkyl Bromides
Reported herein is a novel visible-light photoredox system with Pd(PPh3)4 as the sole catalyst for the realization of the first direct cross-coupling of C(sp3)?H bonds in N-aryl tetrahydroisoquinolines with unactivated alkyl bromides. Moreover, intra- and intermolecular alkylations of heteroarenes were also developed under mild reaction conditions. A variety of tertiary, secondary, and primary alkyl bromides undergo reaction to generate C(sp3)?C(sp3) and C(sp2)?C(sp3) bonds in moderate to excellent yields. These redox-neutral reactions feature broad substrate scope (>60 examples), good functional-group tolerance, and facile generation of quaternary centers. Mechanistic studies indicate that the simple palladium complex acts as the visible-light photocatalyst and radicals are involved in the process.
Zhou, Wen-Jun,Cao, Guang-Mei,Shen, Guo,Zhu, Xing-Yong,Gui, Yong-Yuan,Ye, Jian-Heng,Sun, Liang,Liao, Li-Li,Li, Jing,Yu, Da-Gang
p. 15683 - 15687
(2017)
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Frank,Foster
p. 1019
(1954)
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Hydrocarbon Functionalization by the (Iodosylbenzene)manganese(IV) Porphyrin Complexes from the (Tetraphenylporphinato)manganese(III)-Iodosylbenzene Catalytic Hydrocarbon Oxidation System. Mechanism and Reaction Chemistry
The two types of complexes isolated from the reaction of (tetraphenylporphinato)manganese(III) derivatives, XMnIIITPP, with iodosylbenzene - IVTPP(OIPh)>2O, 1, X = Cl- or Br-, and IVTPP>2O, 2, X = N3- - are capable of oxidizing alkane substrates in good yields at room temperature.Several lines of evidence establish the intermediacy of free alkyl radicals in the reactions of 1 and 2 with alkanes.Oxygen exchange with water in both the iodosyl (Mn-O-I) and μ-oxo (Mn-O-Mn) moieties of 1 suggests the formation of oxo manganese porphyrin complexes from these moieties.Hydrogen abstraction from the alkane substrate by an oxo manganese porphyrin intermediate is postulated to be mechanism for reaction of 1 and 2 with alkanes.Observation of a monomeric manganese(IV) porphyrin intermediate by EPR spectroscopy during the reactions of 1 with alkanes is consistent with the formation of a hydroxymanganese(IV) porphyrin complex resulting from substrate hydrogen abstraction by an oxo intermediate.The formation of RX product from oxidation of RH by 1 has been determined to result from ligand-transfer oxidation of free alkyl radicals by the porphyrin complexes in solution.Through competition reactions and time-dependent product formation studies, ligand-transfer oxidation by XMnIIITPP was found to be the major pathway for RX production.Observation of MnIITPP by EPR spectroscopy during the reactions of 1 with alkanes supports this conclusion.Formation of ROH product may result from ligand-transfer oxidation of free radicals or from the collapse of an intermediate caged radical pair.The mechanism of ROH product formation in the caged radical pair is postulated to be an outer-sphere electron-transfer process due to the expected slow rate of inner-sphere ligand transfer for the high-spin d3 hydroxymanganese(IV) porphyrin complex.Thus the ability of the substrate radical to undergo electron-transfer oxidation determines the ratio of radicals that undergo cage escape to give free radicals to radicals that undergo oxidation and subsequent formation of alcohol product in the caged species.Studies with tertiary substrates support these conclusions.
Smegal, John A.,Hill, Craig L.
p. 3515 - 3521
(1983)
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Highly powerful and practical acylation of alcohols with acid anhydride catalyzed by Bi(OTf)3
Bi(OTf)3-catalyzed acylation of alcohols with acid anhydride was evaluated in comparison with other acylation methods. The Bi(OTf)3/acid anhydride protocol was so powerful that sterically demanding or tertiary alcohols could be acylated smoothly. Less reactive acylation reagents such as benzoic and pivalic anhydride are also activated by this catalysis. In these cases, a new technology was developed in order to overcome difficulty in separation of the acylated product from the remaining acylating reagent: methanolysis of the unreacted anhydride into easily separable methyl ester realized quite easy separation of the desired acylation product. The Bi(OTf)3/acid anhydride protocol was applicable to a wide spectrum of alcohols bearing various functionalities. Acid-labile THP- or TBS-protected alcohol, furfuryl alcohol, and geraniol could be acylated as well as base-labile alcohols. Even acylation of functionalized tertiary alcohols was effected at room temperature.
Orita,Tanahashi,Kakuda,Otera
p. 8926 - 8934
(2001)
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UN NOVEAU SYNTHON ORGANOSILICIE: LE BENZYLTRIMETHYLSILANE
In the presence of tetrabutylammonium fluoride (TBAF) as the catalyst, benzyltrimethylsilane adds to aldehydes and ketones to afford, upon hydrolysis, the corresponding alcohols.The use of PhCH2SiMe3 as a general benzylation reagent is here reported for the first time.
Bennetau, Bernard,Dunogues, Jacques
p. 4217 - 4218
(1983)
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A polymer-supported diacetatobis(2-quinolylbenzimidazole)copper(II) complex as an efficient catalyst for oxidation of alcohols with tert-butyl hydroperoxide
A polymer-supported diacetatobis(2-quinolylbenzimidazole)copper(II) complex [PS-(QBIM)2Cu(II)] was synthesized by functionalization of chloromethylated polystyrene cross-linked with 6.5 % divinyl benzene with 2-(2′-quinolyl)benzimidazole and subsequent treatment with Cu(OAc) 2 in methanol. The complex was characterized by physical, analytical and spectroscopic techniques. Electronic and ESR spectra, together with magnetic susceptibility measurements, indicated that the complex was paramagnetic with distorted octahedral geometry around the copper. The complex was found to be active toward oxidation of various alcohols including phenol, benzyl alcohol and cyclohexanol using 70 % aqueous tert-butyl hydroperoxide under mild conditions. Under the optimized reaction conditions, cyclohexanol gave 100 % conversion to cyclohexanone, benzyl alcohol gave 98 % yield of benzaldehyde and phenol gave 89 % yield of catechol and 4 % of hydroquinone. The complex was recycled five times without much loss in catalytic activity.
Shilpa,Gayathri
p. 53 - 62
(2013)
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Generation of Anionic Intermediates by Intramolecular Nucleophilic Attack at Silicon
Benzyl and allyl anion equivalents can be generated from benzyl- and allylsilanes by intramolecular alkoxide attack.
Hudrlik, Paul F.,Abdallah, Yousef M.,Hudrlik, Anne M.
p. 6747 - 6750
(1992)
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Ultrafast Grignard addition reactions in the presence of water
The addition of allylmagnesium bromide and benzylmagnesium chloride to carbonyl compounds was investigated in the presence of protic reagents such as water and the rate of carbonyl addition was found to be comparable to the rate of protonation by the reagent. The Royal Society of Chemistry 2010.
Osztrovszky, Gyorgyi,Holm, Torkil,Madsen, Robert
p. 3402 - 3404
(2010)
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Controlled stepwise release of fragrance alcohols from dendrimer-based 2-carbamoylbenzoates by neighbouring group participation
2-Carbamoylbenzoates which are chemically bound to the surface of dendrimers were found to release tertiary fragrance alcohols by neighbouring group assisted alkaline hydrolysis under mild reaction conditions. Owing to the excellent separation of the intermediate reaction products by analytical HPLC, the kinetic rate constants of the first two consecutive reaction steps of fragrance release could be determined for a series of modified dendrimers with increasing size. Because of the intramolecular neighbouring group effect, the kinetic rate constants were found to be independent of the dendrimer generation and are not influenced by steric effects on the surface of the macromolecules. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
Frerot, Eric,Herbal, Karim,Herrmann, Andreas
p. 967 - 971
(2003)
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Preparation of Samarium(II) Triflate and It Mediated Grignard-type Reaction. In Situ Formation and Reaction of New Organosamarium Reagents
Samarium(II) triflate was readily prepared by reaction of samarium(III) triflate with sec-butyllithium at room temperature in THF.Its reducing ability was examined by pinacol coupling of carbonyl compounds.Sm(OTf)2 mediated Grignard-type reaction in THF-HMPA effectively; alkylation and allylation of ketones or aldehydes by simple alkyl, allyl, and benzyl halides proceeded via organosamarium intermediates.
Fukuzawa, Shin-ichi,Tsuchimoto, Teruhisa,Kanai, Takeshi
p. 1981 - 1984
(1994)
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Samarium-mediated Barbier reaction of carbonyl compounds
Samarium metal in the presence of catalytic amounts of iodine was found to be effective for the Barbier reaction of carbonyl compounds.
Basu, Manas K.,Banik, Bimal K.
p. 187 - 189
(2001)
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Highly reactive and chemoselective cleavage of allyl esters using an air- and moisture-stable [CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF6 catalyst
A new catalytic process for allyl ester cleavage has been developed by using a robust cationic CpRu(IV) π-allyl complex of 2-quinolinecarboxylic acid that can be stored for over six months in air without any loss of catalytic activity. The deprotection of various alcohols and acids can be attained simply with high reactivity and chemoselectivity under mild conditions. Furthermore, with continuous removal of the low-boiling point coproduct, a turnover number of 1 000 000 can be achieved.
Tanaka, Shinji,Saburi, Hajime,Murase, Takanori,Ishibashi, Yoshitaka,Kitamura, Masato
p. 295 - 298
(2007)
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REACTIVITE DE LA LIAISON δ ACTINIDE-CARBONE : LE TRIS(BISTRIMETHYLSILYLAMIDO)METHYLURANIUM, UN AGENT METHYLANT NUCLEOPHILE A HAUTE SELECTIVITE
The title compound 1 reacts with carbonyl derivatives as a very highly selective nucleophilic methylating reagent.
Dormond, A.,Aaliti, A.,Moise,, C.
p. 1497 - 1498
(1986)
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[CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF 6 complex: A robust catalyst for the cleavage and formation of allyl ethers
A facile and efficient method for the quantitative synthesis of [CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF 6 from [CpRu(CH3CN)3]PF6, 2-quinolinecarboxylic acid, and 2-propen-1-ol has been established. The cationic Ru(IV) complex is air- and moisture-stable, and can be stored in a vial for at least six months. This complex realizes a simple and easy operation for both the deallylation of allyl ethers in methanol and the dehydrative allylation of alcohols. Furthermore, with removal of the volatile allyl methyl ether co-product from the reaction system, the robust catalyst can attain a turnover of 10000 cycles of allyl ether cleavage.
Tanaka, Shinji,Saburi, Hajime,Kitamura, Masato
p. 375 - 378
(2006)
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Tuning the Diiron Core Geometry in Carboxylate-Bridged Macrocyclic Model Complexes Affects Their Redox Properties and Supports Oxidation Chemistry
We introduce a novel platform to mimic the coordination environment of carboxylate-bridged diiron proteins by tethering a small, dangling internal carboxylate, (CH2)nCOOH, to phenol-imine macrocyclic ligands (H3PIMICn). In the presence of an external bulky carboxylic acid (RCO2H), the ligands react with [Fe2(Mes)4] (Mes = 2,4,6-trimethylphenyl) to afford dinuclear [Fe2(PIMICn)(RCO2)(MeCN)] (n = 4-6) complexes. X-ray diffraction studies revealed structural similarities between these complexes and the reduced diiron active sites of proteins such as Class I ribonucleotide reductase (RNR) R2 and soluble methane monooxygenase hydroxylase. The number of CH2 units of the internal carboxylate arm controls the diiron core geometry, affecting in turn the anodic peak potential of the complexes. As functional synthetic models, these complexes facilitate the oxidation of C-H bonds in the presence of peroxides and oxo transfer from O2 to an internal phosphine moiety.
Wang, Fang,Becker, Sabine,Minier, Mikael A.,Loas, Andrei,Jackson, Megan N.,Lippard, Stephen J.
p. 11050 - 11058
(2017)
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The chemistry of alkylstrontium halide analogues, Part 2: Barbier-type dialkylation of esters with alkyl halides
The chemistry of an alkylstrontium halide analogue was examined. In the presence of metallic strontium, the Barbier-type alkylation of esters with alkyl iodides proceeded smoothly at room temperature, under argon, to afford the corresponding dialkylated alcohols in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Miyoshi, Norikazu,Matsuo, Tsuyoshi,Wada, Makoto
p. 4253 - 4255
(2005)
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Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
supporting information
p. 8738 - 8741
(2021/09/08)

An asymmetric Salamo-based Zn complex supported on Fe3O4MNPs: a novel heterogeneous nanocatalyst for the silyl protection and deprotection of alcohols under mild conditions
In this study, a magnetic asymmetric Salamo-based Zn complex (H2L = salen type di-Schiff bases)-supported on the surface of modified Fe3O4(Fe3O4@H2L-Zn) as a new catalyst was designed and characterizedvianumerous analytical techniques such as FT-IR spectroscopy, XRD, EDS, ICP-AES, SEM, TEM, TGA and VSM. An efficient and sustainable synthetic protocol has been presented for the synthesis of silyl ether substructuresviathe silyl protection of alcohols under mild conditions. The synthetic protocol involves a two-component solvent-free reaction between various hydroxyl-bearing substrates and hexamethyldisilazane (HMDS) as an inexpensive silylating agent using Fe3O4@H2L-Zn MNPs as a magnetically separable, recyclable and reusable heterogeneous catalyst. Fe3O4@H2L-Zn MNPs were also applied for the removal of silyl protecting groups from hydroxyl functions using water in CH2Cl2under green conditions. The catalyst demonstrated good to excellent catalytic yield efficiency for both the reactions compared to the commercial metal-based catalysts under green conditions for a wide range of substrates.
Yao, Hongyan,Wang, Yongsheng,Razi, Maryam Kargar
p. 12614 - 12625
(2021/04/14)

An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
p. 8042 - 8048
(2020/09/21)

DECOMPOSITION OF ORGANIC PEROXIDES AND HYDROGEN PEROXIDE BY THE IRON THIOLATES AND RELATED COMPLEXES
Disclosed herein is a method of reducing or disproportionating peroxide, comprising combining an organic chalcogenide, an iron salt, and the peroxide in the presence of an additional reductant, which can be the organic chalcogenide. The method can be used to, e.g., prepare alcohols from peroxides and to disproportionate hydrogen peroxide into water and oxygen.
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Paragraph 0730; 0733; 0786-0792

(2020/07/04)

Photocatalytic carbanion generation-benzylation of aliphatic aldehydes to secondary alcohols
We present a redox-neutral method for the photocatalytic generation of carbanions. Benzylic carboxylates are photooxidized by single electron transfer; immediate CO2 extrusion and reduction of the in situ formed radical yields a carbanion capable of reacting with aliphatic aldehydes as electrophiles giving the Grignard analogous reaction product.
Donabauer, Karsten,Maity, Mitasree,Berger, Anna Lucia,Huff, Gregory S.,Crespi, Stefano,K?nig, Burkhard
p. 5162 - 5166
(2019/06/05)

Oxidative Deprotection of p-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis
An efficient and greener deprotection method for p-methoxybenzyl (PMB) ethers using a metal-free visible light photoredox catalyst and air and ammonium persulfate as the terminal oxidants is presented. Various functional groups and protecting groups were tolerated in the developed method to achieve good to excellent yields in short reaction times. Significantly, the developed method was compatible with PMB ethers derived from primary, secondary, and tertiary alcohols and a gram-scale reaction. Mechanistic studies support a proposed reaction mechanism that involves single electron oxidation of the PMB ether.
Ahn, Deok Kyun,Kang, Young Woo,Woo, Sang Kook
p. 3612 - 3623
(2019/03/11)

Silica gel-mediated hydrohalogenation of unactivated alkenes using hydrohalogenic acids under organic solvent-free conditions
Silica gel-mediated hydrochlorination of unactivated alkenes using 35% hydrochloric acid under organic solvent-free conditions proceeded to give the corresponding chlorides in good yields. Hydrobromination or hydriodination using 47% hydrobromic acid or 55% hydriodic acid afforded the corresponding halides, respectively. Silica gel could be recycled five times without any significant loss of activities.
Tanemura, Kiyoshi
supporting information
p. 4293 - 4298
(2018/11/10)

Mild alkaline hydrolysis of hindered esters in non-aqueous solution
Sterically hindered esters of carboxylic acids, which are considered very resistant to saponification, were rapidly and efficiently saponified in a non-aqueous medium using NaOH in MeOH/CH2Cl2 (1:9) at room temperature. Furthermore, this reaction protocol was extended and successfully applied to the hydrolysis of tosylates and N-tosyl indoles.
Theodorou, Vassiliki,Alagiannis, Michalis,Ntemou, Nikoleta,Brentas, Alexios,Voulgari, Pinelopi,Polychronidou, Vasiliki,Gogou, Marina,Giannelos, Marios,Skobridis, Konstantinos
p. 308 - 319
(2018/11/26)

Hypervalent iodine(III)-mediated decarboxylative acetoxylation at tertiary and benzylic carbon centers
The decarboxylative acetoxylation of carboxylic acids using a combination of PhI(OAc)2 and I2 in a CH2Cl2/AcOH mixed solvent is reported. The reaction was successfully applied to two types of carboxylic acids containing an α-quaternary and a benzylic carbon center under mild reaction conditions. The resulting acetates were readily converted into the corresponding alcohols by hydrolysis.
Kiyokawa, Kensuke,Okumatsu, Daichi,Minakata, Satoshi
supporting information
p. 1046 - 1050
(2019/11/11)

Iron-Catalyzed Nucleophilic Addition Reaction of Organic Carbanion Equivalents via Hydrazones
Earth-abundant and well-defined iron complexes are found to be cheap and effective catalysts for a series of "umpolung" nucleophilic additions of hydrazones. The new catalytic system not only maintains the broad substrate scope of an earlier expensive ruthenium system but also attains chemoselectivity of different kinds of carbonyl groups. Furthermore, the iron catalyst enables this reaction at ambient temperature.
Li, Chen-Chen,Dai, Xi-Jie,Wang, Haining,Zhu, Dianhu,Gao, Jian,Li, Chao-Jun
supporting information
p. 3801 - 3805
(2018/07/25)

The Oxidation of Hydrophobic Aromatic Substrates by Using a Variant of the P450 Monooxygenase CYP101B1
The cytochrome P450 monooxygenase CYP101B1, from a Novosphingobium bacterium is able to bind and oxidise aromatic substrates but at a lower activity and efficiency than norisoprenoids and monoterpenoid esters. Histidine 85 of CYP101B1 aligns with tyrosine 96 of CYP101A1, which, in the latter enzyme forms the only hydrophilic interaction with its substrate, camphor. The histidine residue of CYP101B1 was mutated to phenylalanine with the aim of improving the activity of the enzyme for hydrophobic substrates. The H85F mutant lowered the binding affinity and activity of the enzyme for β-ionone and altered the oxidation selectivity. This variant also showed enhanced affinity and activity towards alkylbenzenes, styrenes and methylnaphthalenes. For example the rate of product formation for acenaphthene oxidation was improved sixfold to 245 nmol per nmol CYP per min. Certain disubstituted naphthalenes and substrates, such as phenylcyclohexane and biphenyls, were oxidised with lower activity by the H85F variant. Variants at H85 (A and G) designed to introduce additional space into the active site so as to accommodate these larger substrates did not improve the oxidation activity. As the H85F mutant of CYP101B1 improved the oxidation of hydrophobic substrates, this residue is likely to be in the substrate binding pocket or the access channel of the enzyme. The side chain of the histidine might interact with the carbonyl groups of the favoured norisoprenoid substrates of CYP101B1.
Sarkar, Md. Raihan,Lee, Joel H. Z.,Bell, Stephen G.
p. 2119 - 2128
(2017/10/12)

Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
supporting information
p. 6592 - 6603
(2017/07/15)

Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds
Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.
Wang, Haining,Dai, Xi-Jie,Li, Chao-Jun
p. 374 - 378
(2017/04/03)

PROCESS FOR PREPARING ARYL KETONE
A process for preparing aryl ketones is disclosed. The process includes photo-oxidizing a compound of formula (V), (VI), (VII) or (VIII): in the presence of an oxidative system comprising at least one bromide compound to form aryl ketones. X1, X2, R1, R2, R3, L1, L2, L3, L4, t, n, m and p have the meanings as described in the specification and claims.
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Paragraph 0154; 0155

(2017/06/12)

Polypeptides having peroxygenase activity and polynucleotides encoding same
The present invention relates to isolated polypeptides having peroxygenase activity, and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
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Page/Page column 37-40

(2016/08/07)

Nonheme iron complex-catalyzed efficient alcohol oxidation by t-BuOOH with N-hydroxyphthalimide (NHPI) as co-catalyst: Implication of high valent iron-oxo species
Two iron catalysts ([Fe(bpc)Cl2][Et4N] (1a) and [Fe(Me2bpb)Cl2][Et3NH] (1b)) displayed efficient catalysis in oxidation of various alcohols to the corresponding carbonyl products using t-BuOOH as an oxidant in the presence of N-hydroxyphthalimide (NHPI) under mild conditions. 1a having an electron-withdrawing group showed a little better catalytic activity than that of 1b with an electron-donating group. The mechanistic studies through Hammett plot, deuterium isotope effect, and the use of 2-methyl-1-phenylprop-2-yl hydroperoxide (MPPH) as a mechanistic probe suggested that the reactive oxidants responsible for the alcohol oxidation possibly involved FeIV[Formula presented]), and phthalimide N-oxyl radical [Formula presented]. On the other hand, the presence of imidazole increased the heterolytic cleavage of Fe-OOR intermediate to form FeV[Formula presented] species and accelerated its [Formula presented] bond cleavage rate. In particular, the formation of FeV[Formula presented] intermediate via the heterolytic cleavage of Fe-OOR species in the presence of imidazole in the catalytic oxidation systems of nonheme iron complexes with t-BuOOH was substantialized, for the first time, to the best of our knowledge.
Bae, Jeong Mi,Lee, Myoung Mi,Lee, Seul Ah,Lee, Sun Young,Bok, Kwon Hee,Kim, Jinheung,Kim, Cheal
p. 8 - 15
(2016/07/14)

Benzyllithiums bearing aldehyde carbonyl groups. A flash chemistry approach
Reductive lithiation of benzyl halides bearing aldehyde carbonyl groups followed by reaction with subsequently added electrophiles was successfully accomplished without affecting the carbonyl groups by taking advantage of short residence times in flow microreactors.
Nagaki, Aiichiro,Tsuchihashi, Yuta,Haraki, Suguru,Yoshida, Jun-ichi
supporting information
p. 7140 - 7145
(2015/07/01)

Synthesis of Ethers via Reaction of Carbanions and Monoperoxyacetals
Although transfer of electrophilic alkoxyl ("RO+") from organic peroxides to organometallics offers a complement to traditional methods for etherification, application has been limited by constraints associated with peroxide reactivity and stability. We now demonstrate that readily prepared tetrahydropyranyl monoperoxyacetals react with sp3 and sp2 organolithium and organomagnesium reagents to furnish moderate to high yields of ethers. The method is successfully applied to the synthesis of alkyl, alkenyl, aryl, heteroaryl, and cyclopropyl ethers, mixed O,O-acetals, and S,S,O-orthoesters. In contrast to reactions of dialkyl and alkyl/silyl peroxides, the displacements of monoperoxyacetals provide no evidence for alkoxy radical intermediates. At the same time, the high yields observed for transfer of primary, secondary, or tertiary alkoxides, the latter involving attack on neopentyl oxygen, are inconsistent with an SN2 mechanism. Theoretical studies suggest a mechanism involving Lewis acid promoted insertion of organometallics into the O-O bond.
Kyasa, ShivaKumar,Meier, Rebecca N.,Pardini, Ruth A.,Truttmann, Tristan K.,Kuwata, Keith T.,Dussault, Patrick H.
p. 12100 - 12114
(2016/01/09)

Catalytic oxidation of alkanes by a (salen)osmium(VI) nitrido complex using H2O2 as the terminal oxidant
The osmium(vi) nitrido complex, [OsVI(N)(L)(CH3OH)]+ (1, L = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) is an efficient catalyst for the oxidation of alkanes under ambient conditions using H2O2 as the oxidant. Alkanes are oxidized to the corresponding alcohols and ketones, with yields up to 75% and turnover numbers up to 2230. Experimental and computational studies are consistent with a mechanism that involves O-atom transfer from H2O2 to [OsVI(N)(L)]+ to generate an [OsVIII(N)(O)(L)]+ active intermediate.
Chen, Man,Pan, Yi,Kwong, Hoi-Ki,Zeng, Raymond J.,Lau, Kai-Chung,Lau, Tai-Chu
supporting information
p. 13686 - 13689
(2015/09/02)

Photoredox removal of p-methoxybenzyl ether protecting group with hydrogen peroxide as terminal oxidant
We report a mild protocol for removal of the p-methoxybenzyl ether protecting group under acidic conditions with eosin Y combined with LEDs as a photoredox catalysis system and hydrogen peroxide as the terminal oxidant. This protocol is compatible with ethers derived from primary, secondary, and tertiary alcohols, as well as with various functional groups. The protocol showed unusual selectivity for a tertiary ether over a primary ether. The scale up to gram scale is also explored and identical reactivity is observed.
Liu, Zheng,Zhang, Yi,Cai, Zheren,Sun, Hao,Cheng, Xu
supporting information
p. 589 - 593
(2015/03/05)

Epoxidation of strained alkenes catalysed by (1,2-dimethyl-4(1H)pyridinone-3-olate)2MnIIICl
The mild epoxidation of strained alkenes using (DMPO)2MnCl catalyst (DMPO = 1,2-dimethyl-4(1H)-pyridinone-3-olate) in the presence of various oxidants was studied. Hydrogen peroxide and monopersulfate were found to be the best oxidants when used with imidazole in acetonitrile at 4 °C, with up to 94% conversion. Dismutation of hydrogen peroxide was also observed when used as an oxidant. The epoxidation using hydrogen peroxide or monoperoxysulfate appears to be mild and very selective for strained alkenes. A mechanism is proposed where imidazole is required for activation of the oxidant and where a detected MnV = O species is proposed as the active species. Competitive reaction between H2O2 and the substrate for the active species is proposed and homolytic vs heterolytic scissions of the OO bond of the oxidant are discussed.
Robinson-Miller, Adam P.,Wyatt, Mark F.,Tétard, David
p. 376 - 390
(2015/01/30)

Transition-metal-free synthesis of phenanthridinones from biaryl-2-oxamic acid under radical conditions
Na2S2O8-promoted decarboxylative cyclization of biaryl-2-oxamic acid for phenanthridinones has been developed. This work illustrates the first example of intramolecular decarboxylative amidation of unactivated arene under transition-metal-free conditions. Additionally, this approach provides an efficient and economical method to access biologically interesting phenanthridinones, an important structure motif in many natural products. (Chemical Equation Presented).
Yuan, Ming,Chen, Li,Wang, Junwei,Chen, Shenjie,Wang, Kongchao,Xue, Yongbo,Yao, Guangmin,Luo, Zengwei,Zhang, Yonghui
supporting information
p. 346 - 349
(2015/02/19)

Mechanochemical ritter reaction: A rapid approach to functionalized amides at room temperature
A fast and efficient mechanochemical Ritter reaction between alcohols and nitriles under mild conditions is demonstrated. The reaction proceeds rapidly at room temperature in a solvent-free or low-solvent environment by using a Br?nsted acid catalyst. Its general application has been verified through a substrate screening comprising a wide range of functionalized nitriles as well as secondary and tertiary alcohols. Gentle Ritter: A fast and efficient mechanochemical Ritter reaction under mild conditions is described. The reaction proceeds rapidly at room temperature in a solvent-free or low-solvent environment by using sulfuric acid as catalyst.
Dokli, Irena,Gredi?ak, Matija
supporting information
p. 2727 - 2732
(2015/04/27)

Highly efficient alkane oxidation catalyzed by [MnV(N)(CN) 4]2-. Evidence for [MnVII(N)(O)(CN) 4]2- as an active intermediate
The oxidation of various alkanes catalyzed by [MnV(N)(CN) 4]2- using various terminal oxidants at room temperature has been investigated. Excellent yields of alcohols and ketones (>95%) are obtained using H2O2 as oxidant and CF3CH 2OH as solvent. Good yields (>80%) are also obtained using (NH4)2[Ce(NO3)6] in CF 3CH2OH/H2O. Kinetic isotope effects (KIEs) are determined by using an equimolar mixture of cyclohexane (c-C6H 12) and cyclohexane-d12 (c-C6D12) as substrate. The KIEs are 3.1 ± 0.3 and 3.6 ± 0.2 for oxidation by H2O2 and Ce(IV), respectively. On the other hand, the rate constants for the formation of products using c-C6H12 or c-C6D12 as single substrate are the same. These results are consistent with initial rate-limiting formation of an active intermediate between [Mn(N)(CN)4]2- and H2O2 or CeIV, followed by H-atom abstraction from cyclohexane by the active intermediate. When PhCH2C(CH3)2OOH (MPPH) is used as oxidant for the oxidation of c-C6H12, the major products are c-C6H11OH, c-C6H10O, and PhCH2C(CH3)2OH (MPPOH), suggesting heterolytic cleavage of MPPH to generate a Mn=O intermediate. In the reaction of H2O2 with [Mn(N)(CN)4]2- in CF 3CH2OH, a peak at m/z 628.1 was observed in the electrospray ionization mass spectrometry, which is assigned to the solvated manganese nitrido oxo species, (PPh4)[Mn(N)(O)(CN)4] -·CF3CH2OH. On the basis of the experimental results the proposed mechanism for catalytic alkane oxidation by [MnV(N)(CN)4]2-/ROOH involves initial rate-limiting O-atom transfer from ROOH to [Mn(N)(CN)4]2- to generate a manganese(VII) nitrido oxo active species, [MnVII(N)(O) (CN)4]2-, which then oxidizes alkanes (R'H) via a H-atom abstraction/O-rebound mechanism. The proposed mechanism is also supported by density functional theory calculations.
Ma, Li,Pan, Yi,Man, Wai-Lun,Kwong, Hoi-Ki,Lam, William W.Y.,Chen, Gui,Lau, Kai-Chung,Lau, Tai-Chu
p. 7680 - 7687
(2014/06/10)

Catalysis and molecular magnetism of dinuclear iron(iii) complexes with N-(2-pyridylmethyl)-iminodiethanol/-ate
The reaction of N-(2-pyridylmethyl)iminodiethanol (H2pmide) and Fe(NO3)3·9H2O in MeOH led to the formation of a dimeric iron(iii) complex, [(Hpmide)Fe(NO3)] 2(NO3)2·2CH3OH (1). Its anion-exchanged form, [(pmide)Fe(N3)]2 (2), was prepared by the reaction of 1 and NaN3 in MeOH, during which the Hpmide ligand of 1 was also deprotonated. These compounds were investigated by single crystal X-ray diffraction and magnetochemistry. In complex 1, one iron(iii) ion was bonded with a mono-deprotonated Hpmide ligand and a nitrate ion. The two iron(iii) ions within the dinuclear unit were connected by two ethoxy groups with an inversion center. In 2, one iron(iii) ion was coordinated with a deprotonated pmide ligand and an azide ion. The Fe(pmide)(N3) unit was related by symmetry through an inversion center. Both 1 and 2 efficiently catalyzed the oxidation of a variety of alcohols under mild conditions. The oxidation mechanism was proposed to involve an FeIVO intermediate as the major reactive species and an FeVO intermediate as a minor oxidant. Evidence for this proposal was derived from reactivity and Hammett studies, KIE (kH/kD) values, and the use of MPPH (2-methyl-1-phenylprop-2-yl hydroperoxide) as a mechanistic probe. Both compounds had significant antiferromagnetic interactions between the iron(iii) ions via the oxygen atoms. 1 showed a strong antiferromagnetic interaction within the Fe(iii) dimer, while 2 had a weak antiferromagnetic coupling within the Fe(iii) dimer.
Shin, Jong Won,Bae, Jeong Mi,Kim, Cheal,Min, Kil Sik
p. 3999 - 4008
(2014/03/21)

Nickel-catalyzed regiodivergent opening of epoxides with aryl halides: Co-catalysis controls regioselectivity
Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position, presumably via TiIII-mediated radical generation. 1,2-Disubstituted epoxides are opened under both conditions to form predominantly the trans product.
Zhao, Yang,Weix, Daniel J.
supporting information
p. 48 - 51
(2014/01/23)

Sulfonylcarbamate as a versatile and unique hydroxy-protecting group: A protecting group stable under severe conditions and labile under mild conditions
The sulfonylcarbamate group is a unique hydroxyl protecting group. In contrast to typical acyl protecting groups, the sulfonylcarbamate group is stable under harsh basic conditions, while showing labile behavior under mild basic conditions. Its compatibility with other hydroxyl protecting groups and application to carbohydrate chemistry is demonstrated.
Manabe, Shino,Yamaguchi, Masanori,Ito, Yukishige
supporting information
p. 8332 - 8334
(2013/09/23)

Application of SO3H silica gel to deprotection of silyl ethers
A newly developed SO3H silica gel cleaved the O-Si bonds in various aryl and alkyl silyl ethers to give the corresponding phenols and alcohols in good to excellent yield. The crude filtrates contained no silyl residues. The solid phase 29Si NMR analyses of the SO3H silica gel strongly suggested that the silyl residues were captured by silanol groups on the surface of the silica gel. The SO3H silica gel could be recycled at least ten times without any loss of activity. The disappearance of silyl residues in the crude filtrate was observed in even the 10th repetition. Our method provides an easily handled desilylation method that requires no further purification. Our method was also applicable to a selective desilylation reaction of a derivative 5 with different siloxy groups or desilylation of an alkaloid derivative 7.
Fujii, Hideaki,Yamada, Takaaki,Hayashida, Kohei,Kuwada, Miki,Hamasaki, Atom,Nobuhara, Kazunori,Ozeki, Sumio,Nagase, Hiroshi
p. 2685 - 2691
(2013/01/15)

Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
p. 15 - 23
(2013/01/14)

Aromatic Hydroxylation at a Non-Heme Iron Center: Observed Intermediates and Insights into the Nature of the Active Species
Mechanism of substrate oxidations with hydrogen peroxide in the presence of a highly reactive, biomimetic, iron aminopyridine complex, [Fe II(bpmen)(CH3CN)2][ClO4] 2 (1; bpmen=N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2- diamine), is elucidated. Complex 1 has been shown to be an excellent catalyst for epoxidation and functional-group-directed aromatic hydroxylation using H2O2, although its mechanism of action remains largely unknown.1, 2 Efficient intermolecular hydroxylation of unfunctionalized benzene and substituted benzenes with H2O2 in the presence of 1 is found in the present work. Detailed mechanistic studies of the formation of iron(III)-phenolate products are reported. We have identified, generated in high yield, and experimentally characterized the key FeIII(OOH) intermediate (Imax=560 nm, rhombic EPR signal with g=2.21, 2.14, 1.96) formed by 1 and H2O2. Stopped-flow kinetic studies showed that FeIII(OOH) does not directly hydroxylate the aromatic rings, but undergoes rate-limiting self-decomposition producing transient reactive oxidant. The formation of the reactive species is facilitated by acid-assisted cleavage of the O-O bond in the iron-hydroperoxide intermediate. Acid-assisted benzene hydroxylation with 1 and a mechanistic probe, 2-Methyl-1-phenyl-2-propyl hydroperoxide (MPPH), correlates with O-O bond heterolysis. Independently generated FeIV=O species, which may originate from O-O bond homolysis in FeIII(OOH), proved to be inactive toward aromatic substrates. The reactive oxidant derived from 1 exchanges its oxygen atom with water and electrophilically attacks the aromatic ring (giving rise to an inverse H/D kinetic isotope effect of 0.8). These results have revealed a detailed experimental mechanistic picture of the oxidation reactions catalyzed by 1, based on direct characterization of the intermediates and products, and kinetic analysis of the individual reaction steps. Our detailed understanding of the mechanism of this reaction revealed both similarities and differences between synthetic and enzymatic aromatic hydroxylation reactions.
Makhlynets, Olga V.,Rybak-Akimova, Elena V.
supporting information; scheme or table
p. 13995 - 14006
(2011/04/12)

Efficient chemoselective addition of grignard reagents to carbonyl compounds in 2-methyltetrahydrofuran
Compared with tetrahydrofuran (THF) as a solvent for the addition reactions between Grignard reagents and carbonyl compounds 2-methyltetrahydrofuran affords the corresponding adducts in higher yields with higher chemoselectivities. Moreover, 2-methyltetrahydrofuran can be readily recycled and reused, which lowers the cost of the process and makes the reaction greener.
Zhong, Weihui,Wu, Yaotiao,Zhang, Xingxian
experimental part
p. 370 - 373
(2009/12/25)

A magnetically separable heterogeneous deallylation catalyst: [CpRu(n 3-C3H5)(2-pyridinecarboxylato)]PF6 complex supported on a ferromagnetic microsize particle Fe3O 4@SiO2
The highly reactive and chemoselective homogeneous deallylation catalyst CpRu(η3-C3H5)(4-substituted-2- pyridinecarboxylato) was immobilized on microsize spherical Fe3O 4@SiO2 particles. The resultant heterogeneous catalyst displays high saturation magnetization, weak coercive forces and high levels of dispersibility. The catalyst has increased the utility of deallylation by allowing the reaction to be conducted without extra additives. The only co-product of the reaction is a volatile allyl ether compound. Here, we demonstrate the efficient deallylation and separation of highly polar multifunctional compounds as well as multiple rounds of catalyst recycling without significant loss of reactivity. The usefulness of this catalyst has been confirmed by the synthesis of a triribonucleotide 3-5 U.
Hirakawa, Takuya,Tanaka, Shinji,Usuki, Naoki,Kanzaki, Hisao,Kishimoto, Mikio,Kitamura, Masato
supporting information; experimental part
p. 789 - 792
(2009/06/28)

P-toluenesulfonyl chloride (p-TsCl)-catalyzed trimethylsilylation of hydroxyl groups using hexamethyldisilazane and their regeneration under mild conditions: The first example for catalytic application of p-toluenesulfonyl chloride
The first catalytic application of p-toluenesulfonyl chloride (p-TsCl) for the efficient and selective trimethylsilylation of various types of hydroxyl groups with hexamethyldisilazane (HMDS) in dichloromethane and desilylation of these compounds in water is reported. The reactions were carried out at room temperature and were found to proceed in good to excellent yields.
Khazaei, Ardeshir,Rostami, Amin,Mantashlo, Fatemeh
experimental part
p. 2288 - 2296
(2010/04/06)

Titanocene-promoted intermolecular couplings of epoxides with nitriles. An easy access to β-hydroxyketones
(Chemical Equation Presented) Radical couplings of epoxides and nitriles mediated by Cp2TiCl provide a diastereoselective route to the synthesis of β-hydroxyketones. The conditions of this "aldol- like" reaction are mild enough to avoid the dehydration of the β-hydroxyketone. The scope of the coupling reaction with functionalized and tetrasubstituted epoxides has been studied. The radical character of the coupling reactions is demonstrated.
Fernandez-Mateos,Encinas Madrazo,Herrero Teijon,Rubio Gonzalez
supporting information; experimental part
p. 3913 - 3918
(2009/10/20)

SUBSTITUTED HETEROCYCLIC COMPOUNDS AND METHODS OF USE
The present invention relates to pyridines, pyrimidines and derivatives thereof, and pharmaceutically acceptable salts thereof. Also included is a method of treatment of inflammation, rheumatoid arthritis, Pagets disease, osteoporosis, multiple myeloma, uveititis, acute or chronic myelogenous leukemia, pancreatic beta cell destruction, osteoarthritis, rheumatoid spondylitis, gouty arthritis, inflammatory bowel disease, adult respiratory distress syndrome (ARDS), psoriasis, Crohn's disease, allergic rhinitis, ulcerative colitis, anaphylaxis, contact dermatitis, asthma, muscle degeneration, cachexia, Reiter's syndrome, type I diabetes, type II diabetes, bone resorption diseases, graft vs. host reaction, Alzheimer's disease, stroke, myocardial infarction, ischemia reperfusion injury, atherosclerosis, brain trauma, multiple sclerosis, cerebral malaria, sepsis, septic shock, toxic shock syndrome, fever, myalgias due to HIV-1, HIV-2, HIV-3, cytomegalovirus (CMV), influenza, adenovirus, the herpes viruses or herpes zoster infection in a mammal comprising administering an effective amount a compound as described above.
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Page/Page column 16

(2010/10/20)

Synthesis of cyclic peroxides by chemo- and regioselective peroxidation of dienes with Co(II)/O2/Et3SiH
(Chemical Equation Presented). In the competitive peroxidation of mixtures of two alkenes with Co(II)/O2/Et3SiH, it was found that the relative reactivities of the alkene substrates are influenced by three major factors:. (1) relative stability of the intermediate carbon-centered radical formed by the reaction of the alkene with HCo(III) complex, (2) steric effects around the C=C double bond, and (3) electronic factors associated with the C=C double bond. Consistent with results from simple alkenes, the chemo-and regioselective peroxidation of dienes was also realized. Depending on the diene structure, the product included not only the expected acyclic unsaturated triethylsilyl peroxides but also 1,2-dioxolane and 1,2-dioxane derivatives via intramolecular cyclization of the unsaturated peroxy radical intermediates.
Tokuyasu, Takahiro,Kunikawa, Shigeki,McCullough, Kevin J.,Masuyama, Araki,Nojima, Masatomo
p. 251 - 260
(2007/10/03)

Method of removing allyl series protecting group using novel ruthenium complex and method of synthesizing allyl ethers
A cyclopentadienyl ruthenium (II) complex or (iv) complex having an α-imino acid type ligand or an α-amino acid type ligand.
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Page/Page column 4

(2010/02/14)

Simple deprotection of acetal type protecting groups under neutral conditions
Heating acetals with ethylene glycol causes the deprotection of acetal type protecting groups. When acetals such as MOM ethers, MEM ethers, and THP ethers were heated in ethylene glycol or propylene glycol, solvolysis proceeded smoothly to produce alcohols in excellent yield. This reaction is a very promising method for chemoselective deprotection of acetal type protecting groups.
Miyake, Hideyoshi,Tsumura, Takatsugu,Sasaki, Mitsuru
p. 7213 - 7215
(2007/10/03)

CpRuIIPF6/quinaldic acid-catalyzed chemoselective allyl ether cleavage. A simple and practical method for hydroxyl deprotection
Matrix presented. A cationic CpRuII complex in combination with quinaldic acid shows high reactivity and chemoselectivity for the catalytic deprotection of hydroxyl groups protected as allyl ethers. The catalyst operates in alcoholic solvents without the need for any additional nucleophiles, satisfying the practical requirements of operational simplicity, safety, and environmental friendliness. The wide applicability of this deprotection strategy to a variety of multifunctional molecules, including peptides and nucleosides, may provide new opportunities in protective group chemistry.
Tanaka, Shinji,Saburi, Hajime,Ishibashi, Yoshitaka,Kitamura, Masato
p. 1873 - 1875
(2007/10/03)