- Stereoselective alkane hydroxylations by metal salts and m-chloroperbenzoic acid
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Simple metal (M=Mn, Fe, Co) perchlorates associated with m-chloroperbenzoic acid are able to conduct stereoselective alkane hydroxylations via a mechanism involving metal-based oxidants; the catalytic activity of the metal salts is in the order of Co(ClO4)2>Mn(ClO4)2>Fe (ClO4)2.
- Nam, Wonwoo,Ryu, Ju Yeon,Kim, Inwoo,Kim, Cheal
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- Participation of two distinct hydroxylating intermediates in iron(III) porphyrin complex-catalyzed hydroxylation of Alkanes
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We have obtained evidence that acylperoxo-iron(III) porphyrin complexes 1a are involved as reactive hydroxylating intermediates in the hydroxylation of alkanes by m-chloroperoxybenzoic acid (m-CPBA) catalyzed by electron-deficient iron(III) porphyrin complexes containing chloride as an anionic axial ligand in a solvent mixture of CH2Cl2 and CH3CN at -40 °C. In addition to the intermediacy of 1a, oxoiron(IV) porphyrin cation radical complexes 2 are formed as the reactive hydroxylating intermediates in the alkane hydroxylations by m-CPBA catalyzed by the iron(III) porphyrin complexes containing triflate (CF3SO3-) as an anionic axial ligand under the same reaction conditions. In line with the recent proposal by Newcomb, Coon, Vaz, and co-workers for cytochrome P-450 reactions, these results suggest that two distinct electrophilic oxidants such as 1a and 2 effect the alkane hydroxylations in iron porphyrin models, depending on the reaction conditions such as the nature of the anionic axial ligands of iron(III) porphyrin complexes.
- Nam,Mi Hee Lim,Sun Kyung Moon,Kim
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- Biomimetic alkane hydroxylation by cobalt(III) porphyrin complex and m-chloroperbenzoic acid
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The catalytic hydroxylation of alkanes by an electron-deficient cobalt(III) porphyrin complex and m-chloroperbenzoic acid yielded alcohols as major products with a high kH/kD value, > 99% retention of stereochemistry, and a high regioselectivity; a high-valent cobalt - oxo porphyrin complex was suggested as a reactive hydroxylating intermediate.
- Nam,Kim,Kim,Kim
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- Stereoselective oxidation of alkanes with: M -CPBA as an oxidant and cobalt complex with isoindole-based ligands as catalysts
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Two complexes with isoindole-core ligands of general formula [M{C6H4C(NH2)NC(ONCMe2)2}2](NO3)2 (M = Co for 1 and M = Ni for 2) were studied as catalysts for the mild stereoselective alkane oxidation with m-chloroperbenzoic acid (m-CPBA) as an oxidant and cis-1,2-dimethylcyclohexane (cis-1,2-DMCH) as a main model substrate. Complex 1 disclosed a pronounced activity, with high retention of stereoconfiguration of substrates (>98% for cis-1,2-DMCH) and highest cis/trans ratio of tertiary alcohols (products) of 56, under mild conditions. The best achieved yields of tertiary cis-alcohols were of 13.7 and 50.5%, based on the substrate (cis-1,2-DMCH) and the oxidant (m-CPBA) respectively. Kinetic experiments, high bond and stereoselectivity parameters, kinetic isotope effect of 7.2(2) in the oxidation of cyclohexane, and incorporation of 18O from H218O support the involvement of CoIVO high-valent metal-oxo intermediates as main C-H attacking species.
- Nesterova, Oksana V.,Kopylovich, Maximilian N.,Nesterov, Dmytro S.
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p. 93756 - 93767
(2016/10/21)
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- Oxidation of Alkanes by Periodate Using a MnV Nitrido Complex as Catalyst
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The design of catalytic systems that can selectively oxidize unactivated C?H bonds under mild conditions is a challenge to chemists. We report here that the manganese(V) nitrido complex [MnV(N)(CN)4]2? is a highly efficient catalyst for the oxidation of alkanes by periodate (IO4 ?) at ambient conditions. Excellent yields of alcohols and ketones (>95 %) are obtained with a maximum turnover number (TON) of 3000.
- Ma, Li,Chen, Lingjing,Lau, Tai-Chu
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p. 2846 - 2848
(2016/10/25)
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- Catalytic oxidation of alkanes by a (salen)osmium(VI) nitrido complex using H2O2 as the terminal oxidant
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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
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supporting information
p. 13686 - 13689
(2015/09/02)
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- P450-catalyzed regio- and stereoselective oxidative hydroxylation of disubstituted cyclohexanes: Creation of three centers of chirality in a single CH-activation event This paper is dedicated to the memory of Harry H. Wasserman
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Wild-type P450-BM3 is able to catalyze in a highly regio- and diastereoselective manner the oxidative hydroxylation of non-activated disubstituted cyclohexane derivatives lacking any functional groups, including cis- and trans-1,2-dimethylcyclohexane, cis- and trans-1,4-dimethylcyclohexane, and trans-1,4-methylisopropylcyclohexane. In all cases except chiral trans-1,2-dimethylcyclohexane as substrate, the single hydroxylation event at a methylene group induces desymmetrization with simultaneous creation of three centers of chirality. Certain mutants increase selectivity, setting the stage for future directed evolution work.
- Ilie, Adriana,Agudo, Rubén,Roiban, Gheorghe-Doru,Reetz, Manfred T.
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p. 470 - 475
(2015/02/02)
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- Highly efficient alkane oxidation catalyzed by [MnV(N)(CN) 4]2-. Evidence for [MnVII(N)(O)(CN) 4]2- as an active intermediate
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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
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p. 7680 - 7687
(2014/06/10)
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- Catalytic oxidation of alkanes by iron bispidine complexes and dioxygen: Oxygen activation versus autoxidation
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Organic substrates (specifically cis-1,2-dimethylcyclohexane, DMCH) are oxidized by O2 in the presence of iron(ii)-bispidine complexes. It is shown that this oxidation reaction is not based on O2 activation by the nonheme iron catalysts as in Nature but due to a radical-based initiation, followed by a radical- and ferryl-based catalytic reaction.
- Comba, Peter,Lee, Yong-Min,Nam, Wonwoo,Waleska, Arkadius
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supporting information
p. 412 - 414
(2014/01/06)
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- Selective activation of secondary C-H bonds by an iron catalyst: Insights into possibilities created by the use of a carboxyl-containing bipyridine ligand
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In this work, we report the discovery of a carboxyl-containing iron catalyst 1 (FeII-DCBPY, DCBPY = 2,2′-bipyridine-4,4′- dicarboxylic acid), which could activate the C-H bonds of cycloalkanes with high secondary (2°) C-H bond selectivity. A turnover number (TN) of 11.8 and a 30% yield (based on the H2O2 oxidant) were achieved during the catalytic oxidation of cyclohexane by 1 under irradiation with visible light. For the transformation of cycloalkanes and bicyclic decalins with both 2° and tertiary (3°) C-H bonds, 1 always preferred to oxidise the 2° C-H bonds to the corresponding ketone and alcohol products; the 2°/3° ratio ranged between 78/22 and >99/1 across 7 examples. 18O isotope labelling experiments, ESR experiments, a PPh3 method and the catalase method were used to characterize the reaction process during the oxidation. The success of 1 showed that, in addition to using a bulky catalyst, high 2° C-H bond selectivity could also be achieved using a less bulky molecular iron complex as the catalyst.
- Cheng, Shi,Li, Jing,Yu, Xiaoxiao,Chen, Chuncheng,Ji, Hongwei,Ma, Wanhong,Zhao, Jincai
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p. 3267 - 3273
(2013/10/01)
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- Oxidation of alkane using Pt/Eu2O3/TiO 2/SiO2 catalyst with O2 and H2 in acetic acid under mild conditions
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A new solid catalyst of Pt/Eu2O3/TiO 2/SiO2 for oxidation of alkane was developed. Oxidation of adamantane using the multi-components supported catalyst with O2 and H2 was studied in acetic acid at 313 K. Several multi-components supported catalysts were prepared and tested the oxidation activity. It is found that loading order of Eu2O3, TiO2 and Pt on the SiO2 support strongly affected the oxidation catalysis. The active catalysts model was proposed from TEM-EDS analysis that very small Pt particles well dispersed on amorphous Eu2O3 and TiO 2 on the SiO2 support. Eu and Ti oxides concertedly activated O2 with electrons supplied from H2 on Pt, and active oxygen species efficiently oxidized adamantane and other alkanes to oxygenated compounds. Active oxygen species could not be identified but its reactivity was studied. It showed radical nature for oxidation of alkanes and a cleavage of C-H bond was the rate-determining step during the oxidation.
- Yamanaka, Ichiro,Suzuki, Yuta,Toida, Masashi
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experimental part
p. 286 - 290
(2011/01/04)
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- Raney Ni-Al alloy-mediated reduction of alkylated phenols in water
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Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a very powerful reducing agent in the hydrogenation of phenol and alkylated phenols to the corresponding cyclohexanol derivatives.
- Tan, Song-Liang,Liu, Guo-Bin,Gao, Xiang,Thiemann, Thies
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experimental part
p. 5 - 7
(2009/09/06)
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- Efficient catalytic oxidation of alkanes by lewis acid/[Os VI(N)Cl4]- using peroxides as terminal oxidants. Evidence for a metal-based active intermediate
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The oxidation of alkanes by various peroxides (tBuOOH, H 2O2, PhCH2C(CH3)2OOH) is efficiently catalyzed by [OsVI(N)Cl4]-/Lewis acid (FeCl3 or Sc(OTf)3) in CH2Cl 2/CH3CO2H to give alcohols and ketones. Oxidations occur rapidly at ambient conditions, and excellent yields and turnover numbers of over 7500 and 1000 can be achieved in the oxidation of cyclohexane with tBuOOH and H2O2, respectively. In particular, this catalytic system can utilize PhCH2C(CH 3)2OOH (MPPH) efficiently as the terminal oxidant; good yields of cyclohexanol and cyclohexanone (>70%) and MPPOH (>90%) are obtained in the oxidation of cyclohexane. This suggests that the mechanism does not involve alkoxy radicals derived from homolytic cleavage of MPPH but is consistent with heterolytic cleavage of MPPH to produce a metal-based active intermediate. The following evidence also shows that no free alkyl radicals are produced in the catalytic oxidation of alkanes: (1) The product yields and distributions are only slightly affected by the presence of O2. (2) Addition of BrCCl3 does not affect the yields of cyclohexanol and cyclohexanone in the oxidation of cyclohexane. (3) A complete retention of stereochemistry occurs in the hydroxylation of cis- and trans-1,2- dimethylcyclohexane. The proposed mechanism involves initial O-atom transfer from ROOH to [OsVI(N)Cl4]-/Lewis acid to generate [OsVIII(N)(O)Cl4]-/Lewis acid, which then oxidizes alkanes via H-atom abstraction.
- Yiu, Shek-Man,Man, Wai-Lun,Lau, Tai-Chu
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scheme or table
p. 10821 - 10827
(2009/02/05)
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- A highly efficient non-heme manganese complex in oxygenation reactions
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A non-heme manganese(ii) complex shows a high catalytic activity in the epoxidation of olefins by iodosyl benzene and in the oxidation of olefins, alcohols and alkanes by peracetic acid; a mechanism involving metal-based oxidants is proposed for the oxida
- Nehru, Kasi,Kim, Soo Jeong,Kim, In Young,Seo, Mi Sook,Kim, Youngmee,Kim, Sung-Jin,Kim, Jinheung,Nam, Wonwoo
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p. 4623 - 4625
(2008/10/09)
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- FeCl3-activated oxidation of alkanes by [Os(N)O 3]-
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Although the ion [OsVIII(N)(O)3]- is a stable species and is not known to act as an oxidant for organic substrates, it is readily activated by FeCl3 in CH2Cl2/CH 3CO2H to oxidize alkanes efficiently at room temperature. The oxidation can be made catalytic by using 2,6-dichloropyridine N-oxide as the terminal oxidant. The active intermediates in stoichiometric and catalytic oxidation are proposed to be [(O)3OsVIII≡N-Fe III] and [Cl4(O)OsVIII≡N-Fe III], respectively.
- Yiu, Shek-Man,Wu, Zhi-Biao,Mak, Chi-Keung,Lau, Tai-Chu
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p. 14921 - 14929
(2007/10/03)
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- Hydroxylation of aliphatic hydrocarbons with m-chloroperbenzoic acid catalyzed by electron-deficient iron(III) porphyrin complexes
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The catalytic hydroxylation of aliphatic hydrocarbons by m- chloroperbenzoic acid (MCPBA) has been studied in the presence of electron- deficient iron(III) porphyrin complexes. High yields of alcohol products were obtained with small amounts of ketone formation under mild reaction conditions. The stereospecificity and regioselectivity of the iron porphyrin complexes have been investigated in hydroxylation reactions as well. The hydroxylation of alkanes has been performed in the presence of isotopically 18O-labeled water, H218O, in order to understand the effects of the electronic nature of iron porphyrin complexes, the concentration of H218O, the C-H bond strength of alkanes, and the reaction temperature on the 18O- incorporation from the labeled water into alcohols. We found that the amounts of 18O incorporated into the alcohol products varied in the reactions; these results were interpreted with that the reaction of oxygen atom transfer from a high-valent iron oxoporphyrin complex to alkanes competes with that of oxygen atom exchange between the intermediate and labeled water that leads to 18O-incorporation from H218O into the alcohol products. Deuterium kinetic isotope effects (KIEs) in the alkane hydroxylations by the iron porphyrin complexes and MCPBA have been studied with a mixture of cyclohexane and cyclohexane-d12. The KIE values obtained in the reactions were found to depend significantly on the nature to the iron porphyrin complexes. The temperature dependence of k(H)/k(D) was also studied from -40 to 25 °C and the parameters of Arrhenius equation (i.e., the pre-exponential factor ratio, A(H)/A(D), and the isotopic difference of C-H and C-D bond activation energies, E(a)(D)-E(a)(H)) were determined.
- Lim, Mi Hee,Lee, Yoon Jung,Goh, Yeong Mee,Nam, Wonwoo,Kim, Cheal
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p. 707 - 713
(2007/10/03)
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- Oxidation with the "H2O2 - Manganese(IV) complex - Carboxylic acid" reagent 1. Oxidation of saturated hydrocarbons with peroxy acids and hydrogen peroxide
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The complex [LMnIV(O)3MnIVL](PF6)2 (1), where L is 1,4,7-trimethyl-1,4,7-triazacyclononane, catalyzes a highly efficient stereoselective oxygenation of saturated hydrocarbons in the presence of H2O2. A carboxylic acid is an obligatory component of the reaction mixture, while acetonitrile or acetone can be used as solvent. The reaction occurs, forming alkyl hydroperoxide, ketone, and alcohol. Substitution at the tertiary carbon atom proceeds more easily than that at the secondary carbon atom, whereas primary C-H bonds are rather inactive. Oxidation of alkanes and alcohols with peroxy acids catalyzed by complex 1 occurs with lower efficiency.
- Shul'pin,Lindsay-Smith
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p. 2379 - 2386
(2007/10/03)
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- Efficient stereoselective oxygenation of alkanes by peroxyacetic acid or hydrogen peroxide and acetic acid catalysed by a manganese(IV) 1,4,7- trimethyl-1,4,7-triazacyclononane complex
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The dinuclear manganese complex [LMn(IV)(O)3Mn(IV)L](PF6)2, where L is 1,4,7-trimethyl-1,4,7-triazacyclononane. catalyses the oxygenation of alkane by peroxyacetic acid or by H2O2 in the presence of acetic acid to give alkanols, alkanones and alkyl hydroperoxides. The reactions can give large turnovers (up to 1350 after 1 h at 20°C) and can occur with a high degree of retention of stereochemistry at tertiary carbon atoms.
- Lindsay Smith, John R.,Shul'pin, Georgiy B.
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p. 4909 - 4912
(2007/10/03)
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- Cycloalkyl esters of mercaptoalkanoic acids
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Described are the cycloalkyl esters of mercaptoalkanoic acids defined according to the structure: STR1 wherein R1 represents hydrogen or methyl; R2 represents mono C1 -C4 alkyl substituted or unsubstituted C5 -C8 cycloalkyl; R3 represents hydrogen or methyl; and N represents 0, 1 or 2 and uses thereof in augmenting or enhancing the aroma or taste of foodstuffs.
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- Syntheses of (+/-)-cis γ-Irone and Its Related Compounds
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(+/-)-cis-γ-Irone (1a), (+/-)-cis-dihydro-γ-irone (2a) and their trans-isomers (1b, 2b) were synthesized via 3,3-(Claisen) or 2,3-sigmatropic rearrangement of 1-hydroxymethyl-3,3,4-trimethyl-1-cyclohexene (8) derivatives as each key step.
- Kawanobe, Tsuneo,Iwamoto, Minoru,Kogami, Kunio,Matsui, Masanao
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p. 791 - 796
(2007/10/02)
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- Stereoselectivity in Organoborane Rearrangement: Relationship to the Mechanism of Hydroboration
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Hydroboration of 1,2-dimethylcyclohexene and subsequent rearrangement of the tertiary to the primary alkylborane occur with substantial (99:1) suprafacial selectivity.Similar though less pronounced behavior is found for the rearrangement of the tertiary to the secondary alkylborane.These results rule out, as the lowest energy pathway, dissociation (dehydroboration) to the free olefins followed by readdition with reversed regiochemistry, since hydroborations of these olefins exhibit little selectivity.The observed stereoselectivity provides strong support for an intra molecular process, most likely involving an intermediate ? complex, which must give rearranged alkylborane faster than dissociated entities.Similar stereochemical results are obtained for the rearrangement in the presence or absence of THF, showing that solvent plays no critical role in the intramolecular migration.As a further mechanistic probe, B2D6 was employed, and the deuterium content was examined in various products.Evidence for an exchange process at the tertiary center β to boron was found.In general, the results are compatible with the proposed ?-complex mechanism.An unusual feature is the incorporation of deuterium at the borane migration terminus, for which a free-radical mechanism is suggested.The rearrangement results are considered in the context of the mechanism of hydroboration.Although a ?-complex intermediate has been suggested for hydroboration, it is concluded that such an intermediate (if it exists) must be fundamentally different from that involved in the rearrangement.This conclusion is surprising considering the close similarities of the two processes.
- Wood, Stanley E.,Rickborn, Bruce
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p. 555 - 562
(2007/10/02)
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- Polycyclic phenols, alcohols and ketones from phenols, cyclic alcohols and cyclic ketones using a nickel oxide/manganese oxide/magnesium oxide catalyst in presence of at least one of hydrogen and nitrogen
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At least one of a polycyclic phenol, a polycyclic alcohol and a polycyclic ketone is produced under hydrogenation conditions using a nickel oxide/manganese oxide/magnesium oxide catalyst by subjecting at least one of a monocyclic ketone, a monocyclic alcohol and a monocyclic phenol to said conditions and said catalyst.
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