- Biocatalytic synthesis of non-vicinal aliphatic diols
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Biocatalysts are receiving increased attention in the field of selective oxyfunctionalization of C-H bonds, with cytochrome P450 monooxygenases (CYP450s), and the related peroxygenases, leading the field. Here we report on the substrate promiscuity of CYP505A30, previously characterized as a fatty acid hydroxylase. In addition to its regioselective oxyfunctionalization of saturated fatty acids (ω-1-ω-3 hydroxylation), primary fatty alcohols are also accepted with similar regioselectivities. Moreover, alkanes such as n-octane and n-decane are also readily accepted, allowing for the production of non-vicinal diols through sequential oxygenation. This journal is
- Ebrecht, Ana C.,Aschenbrenner, Jasmin C.,Smit, Martha S.,Opperman, Diederik J.
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supporting information
p. 439 - 445
(2021/01/29)
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- Catalytic deoxygenation of bio-based 3-hydroxydecanoic acid to secondary alcohols and alkanes
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This work comprises the selective deoxygenation of bio-derivable 3-hydroxydecanoic acid to either linear alkanes or secondary alcohols in aqueous phase and H2-atmosphere over supported metal catalysts. Among the screened catalysts, Ru-based systems were identified to be most active. By tailoring the catalyst, the product selectivity could be directed to either secondary alcohols or linear alkanes. In the absence of a Br?nsted acidic additive, 2-nonanol and 3-decanol were accessible with a yield of 79% and 6% respectively, both of which can be used in food and perfume industries as flavoring agents and fragrances. To produce alkanes, we successfully synthesized a bifunctional Ru/HZSM-5 catalyst. The acidic zeolite support facilitated the dehydration of the intermediary formed alcohols to alkenes, while the following hydrogenation occurred at the Ru centers. Thus, full 3-hydroxydecanoic acid deoxygenation to nonane and decane, which are both well-established as diesel and jet fuels, was achieved with up to 72% and 12% yield, respectively.
- Artz, Jens,Brosch, Sebastian,Golchert, Christiane,Hergesell, Adrian H.,Mensah, Joel B.,Palkovits, Regina
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supporting information
p. 3522 - 3531
(2020/08/28)
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- CYP505E3: A Novel Self-Sufficient ω-7 In-Chain Hydroxylase
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The self-sufficient cytochrome P450 monooxygenase CYP505E3 from Aspergillus terreus catalyzes the regioselective in-chain hydroxylation of alkanes, fatty alcohols, and fatty acids at the ω-7 position. It is the first reported P450 to give regioselective in-chain ω-7 hydroxylation of C10–C16 n-alkanes, thereby enabling the one step biocatalytic synthesis of rare alcohols such as 5-dodecanol and 7-tetradecanol. It shows more than 70 percent regioselectivity for the eighth carbon from one methyl terminus, and displays remarkably high activity towards decane (TTN≈8000) and dodecane (TTN≈2000). CYP505E3 can be used to synthesize the high-value flavour compound δ-dodecalactone via two routes: 1) conversion of dodecanoic acid into 5-hydroxydodecanoic acid (24 percent regioselectivity), which at low pH lactonises to δ-dodecalactone, and 2) conversion of 1-dodecanol into 1,5-dodecanediol (55 percent regioselectivity), which can be converted into δ-dodecalactone by horse liver alcohol dehydrogenase.
- Maseme, Mpeyake Jacob,Opperman, Diederik Johannes,Pennec, Alizé,Smit, Martha Sophia,van Marwijk, Jacqueline
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supporting information
p. 10359 - 10362
(2020/04/23)
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- Efficient and versatile catalysis for β-alkylation of secondary alcohols through hydrogen auto transfer process with newly designed ruthenium(II) complexes containing ON donor aldazine ligands
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A new series of ruthenium(II) carbonyl complexes, [RuCl(CO)(EPh3)2(L1-2)] (1–4) (E?=?P or As; H2L1?=?salicylaldazine, H2L2?=?2-hydroxynaphthaldazine), have been assembled from ruthenium(II) precursors [RuHCl(CO)(EPh3)3] and bidentate ON donor Schiff base ligands (H2L1-2). Both ligands and their new ruthenium(II) complexes have been characterized by elemental analyses, spectroscopic methods (UV, IR, NMR (1H, 13C, 31P) as well as ESI mass spectrometry. The molecular structures of H2L1 and 1 have been confirmed by single crystal X-ray diffraction. Based on the above studies, an octahedral coordination geometry around the metal center has been proposed for 1–4. To investigate the catalytic effectiveness of 1–4, the complexes have been used as catalysts in β-alkylation of secondary alcohols with primary alcohols and synthesis of quinolines. The effect of solvent, time, base, catalyst loading, and substituent of the ligand moiety on the reaction was studied. Notably, 1 was a more efficient catalyst toward alkylation of a wide range of alcohols and quinolines synthesis. The reusability of the catalyst was checked and the results showed up to six catalytic runs without significant loss of activity.
- Premkumar, Periyasamy,Manikandan, Rajendran,Nirmala, Muthukumaran,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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p. 3065 - 3079
(2017/10/11)
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- N-Heterocyclic olefins as ancillary ligands in catalysis: A study of their behaviour in transfer hydrogenation reactions
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The Ir(i) complexes [Ir(cod)(κP,C,P′-NHOPPh2)]PF6 and [IrCl(cod)(κC-NHOOMe)] (cod = 1,5-cyclooctadiene, NHOPPh2 = 1,3-bis(2-(diphenylphosphanyl)ethyl)-2-methyleneimidazoline) and NHOOMe = 1,3-bis(2-(methoxyethyl)-2-methyleneimidazoline), both featuring an N-heterocyclic olefin ligand (NHO), have been tested in the transfer hydrogenation reaction; this representing the first example of the use of NHOs as ancillary ligands in catalysis. The pre-catalyst [Ir(cod)(κP,C,P′-NHOPPh2)]PF6 has shown excellent activities in the transfer hydrogenation of aldehydes, ketones and imines using iPrOH as a hydrogen source, while [IrCl(cod)(κC-NHOOMe)] decomposes throughout the reaction to give low yields of the hydrogenated product. Addition of one or two equivalents of a phosphine ligand to the latter avoids catalyst decomposition and significantly improves the reaction yields. The reaction mechanism has been investigated by means of stoichiometric studies and theoretical calculations. The formation of the active species ([Ir(κP,C,P′-NHOPPh2)(iPrO)]) has been proposed to occur via isopropoxide coordination and concomitant COD dissociation. Moreover, throughout the catalytic cycle the NHO moiety behaves as a hemilabile ligand, thus allowing the catalyst to adopt stable square planar geometries in the transition states, which reduces the energetic barrier of the process.
- Iturmendi, Amaia,García, Nestor,Jaseer,Munárriz, Julen,Sanz Miguel, Pablo J.,Polo, Victor,Iglesias, Manuel,Oro, Luis A.
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p. 12835 - 12845
(2016/08/24)
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- ALKANE OXIDATION BY MODIFIED HYDROXYLASES
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This invention relates to modified hydroxylases. The invention further relates to cells expressing such modified hydroxylases and methods of producing hydroxylated alkanes by contacting a suitable substrate with such cells.
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Paragraph 0341
(2016/02/16)
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- Ruthenium nanoparticle-intercalated montmorillonite clay for solvent-free alkene hydrogenation reaction
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Well-characterized, ruthenium nanoparticle-intercalated montmorillonite clay was used as a catalyst in solvent-free alkene hydrogenation reactions and the corresponding products were obtained in good yields. The catalytic activity of ruthenium nanoparticle-intercalated montmorillonite clay was successfully tested with 16 different functionalized and non-functionalized alkenes. Apart from alkene reduction, the ruthenium nanoparticle-intercalated montmorillonite clay was also tested in Wittig-type reactions for obtaining dehydrobrittonin A, an important intermediate for the synthesis of brittonin A. Ruthenium nanoparticle-intercalated montmorillonite clay was found to be active in the synthesis of dehydrobrittonin A and brittonin A. The ability to recycle the catalyst nine times, together with low catalyst loading, high catalytic activity and catalytic selectivity were noteworthy advantages of the proposed protocol.
- Upadhyay, Praveenkumar,Srivastava, Vivek
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p. 740 - 745
(2015/02/05)
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- Revisiting cytochrome P450-mediated oxyfunctionalization of linear and cyclic alkanes
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Cytochrome P450 monooxygenases (CYPs) of the CYP153 family catalyse terminal hydroxylation of n-alkanes. Alkane hydroxylating mutants of self-sufficient CYP102A1 have also been described. We evaluated two CYP153s (a three-component system and a fused self-sufficient CYP), wildtype CYP102A1 and nine CYP102A1 mutants, for the conversion of three cycloalkanes (C6, C7 and C8) and three n-alkanes (C6, C8 and C10) using whole cells (WCs) and crude cell-free extracts (CFEs). The aim was to identify substrate-enzyme combinations that give high product titres and space-time yields (STYs). Comparisons were made using total turnover numbers (TTNs) and turnover frequencies (TOFs) to normalize for CYP expression. Reactions were carried out using high enzyme and substrate concentrations compatible with high STYs. Under these conditions CYP102A1 and the double R47L,Y51F mutant, although not regioselective, performed better on all substrates in terms of product titres over 8 h, and thus STYs and TTNs, than heavily mutated variants that have been reported to give very high TOFs. CYP153A6, with its ferredoxin (Fdx) and ferredoxin reductase (FdR), emerged as the superior catalyst for conversion of n-alkanes. In addition to its excellent regioselectivity it also gave the highest final product titres and STYs in WC conversions of hexane and octane. Interaction with FdR and Fdx initially limited performance in CFEs, but with additional FdR and Fdx gave 1-octanol titres of 50 mmol·LBRM-1 and TTNs exceeding 12,000 over 18 h, rivalling results reported with self-sufficient CYPs. Selecting biocatalysts for application requires caution, since experimental conditions such as amount of substrate added and solubility as well as cofactor dependence and regeneration can have a profound effect on catalyst performance, while stability and efficiency with regard to cofactor usage (coupling efficiency) are at least as important as TOFs when high product titres and STYs are the target.
- Pennec, Aliz,Jacobs, Cheri L.,Opperman, Diederik J.,Smit, Martha S.
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supporting information
p. 118 - 130
(2015/01/30)
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- Selective transformations of carbonyl functions in the presence of α,β-unsaturated ketones: Concise asymmetric total synthesis of decytospolides A and B
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Enones selectively react with a combination of PPh3 and TMSOTf to produce phosphonium silyl enol ethers, which work as protective groups of enones during the reduction of other carbonyl functions and can be easily deprotected to regenerate parent enones at workup. Furthermore, the first ketone selective alkylations in the presence of enones were also accomplished. This in situ protection method was applied to concise asymmetric total syntheses of decytospolides A and B.
- Yahata, Kenzo,Minami, Masaki,Watanabe, Kei,Fujioka, Hiromichi
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supporting information
p. 3680 - 3683
(2014/08/05)
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- Tandem isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols using Rh/Ru dual-or ternary-catalyst systems
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A one-pot three-step reaction, isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols, was accomplished by employing a Rh/Ru dual-catalyst system. By using a combination of Rh(acac)(CO)2/ bisphosphite and Shvo's catalyst, (Z)-2-tridecene was converted to 1-tetradecanol in 83% yield with high normal/iso selectivity (n/i = 12). The method was applicable to other internal alkenes, including functionalized alkenes, such as an alkenol and an alkenoate. Furthermore, addition of a third component, Ru3(CO)12, effectively improved the n/i ratio in the tandem isomerization/hydroformylation/hydrogenation of methyl oleate (from n/i = 1.9 to 4.4). Control experiments revealed that the isomerization was mediated by both Rh and Ru and that the coexistence of Rh and Ru was essential for hydrogenation of aldehyde under H2/CO.
- Yuki, Yamato,Takahashi, Kohei,Tanaka, Yoshiyuki,Nozaki, Kyoko
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p. 17393 - 17400
(2014/01/06)
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- Low-temperature aerobic oxidation of decane using an oxygen-free radical initiator
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The direct selective oxidation of long chain alkanes by O2 is a highly demanding reaction. We have shown that it is possible to oxidise n-decane in the presence of the oxygen-free radical initiator azobisisobutyronitrile. Formation of a range of oxygenated products has been observed under relatively mild conditions (70 °C in air). Although the presence of a catalyst is not essential when the initiator is used, ceria-based catalysts have been found to increase the selectivity to alcohols by modifying the oxyfunctionalisation of decane.
- Lloyd, Rhys,Jenkins, Robert L.,Piccinini, Marco,He, Qian,Kiely, Christopher J.,Carley, Albert F.,Golunski, Stanislaw E.,Bethell, Donald,Bartley, Jonathan K.,Hutchings, Graham J.
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scheme or table
p. 161 - 167
(2011/11/30)
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- Transfer hydrogenation of olefins catalysed by nickel nanoparticles
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Nickel nanoparticles have been found to effectively catalyse the hydrogen-transfer reduction of a variety of non-functionalised and functionalised olefins using 2-propanol as the hydrogen donor. The heterogeneous process has been shown to be highly chemoselective for certain substrates, with all the corresponding alkanes being obtained in high yields. A synthesis of the natural dihydrostilbene brittonin A?is also reported based on the use of nickel nanoparticles.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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experimental part
p. 10637 - 10643
(2010/01/16)
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- Regio- And stereoselective subterminal hydroxylations of n-decane by fungi in a liquid-liquid interface bioreactor (L-L IBR)
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This article may be the first report to describe the excellent regio- and stereoselective subterminal hydroxylations of n-alkane with microorganisms. Approximately 2000 fungal strains were screened for the regioselective hydroxylation of n-decane with a s
- Oda, Shinobu,Isshiki, Kunio,Ohashi, Shinichi
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experimental part
p. 105 - 109
(2009/04/10)
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- Macrolides from the scent glands of the tropical butterflies Heliconius cydno and Heliconius pachinus
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The four major components present in scent gland extracts of the male Costa Rica longwing butterflies Heliconius cydno and Heliconius pachinus were identified as 12- and 14-membered macrolides containing a C18-carbon skeleton. By use of micro-reactions and spectrometric examinations, structural proposals were made and subsequently proven by synthesis, using ring-closing-metathesis as the key steps. These macrolides, (9Z,11E,13S)- octadeca-9,11-dien-13-olide (5, S-coriolide), (9Z,11E,13S,15Z)-octadeca-9,11,15- trien-13-olide (6), (9Z,13S)-octadec-9-en-13-olide (13), and (9Z,11S)-octadec-9-en-11-olide (25), are biosynthetically obviously derived from oleic, linoleic, and linolenic acids. Their absolute configurations were determined by gas chromatographic investigations on chiral phases, showing all to possess (S)-configuration. The Royal Society of Chemistry.
- Schulz, Stefan,Yildizhan, Selma,Stritzke, Katja,Estrada, Catalina,Gilbert, Lawrence E.
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p. 3434 - 3441
(2008/09/19)
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- Titanocene-catalyzed regiodivergent epoxide openings
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The first regiodivergent opening of unbiased epoxides providing the ring-opened products in high enantiomeric excess from racemic and exceptionally high enantiomeric excess from enantioenriched substrates in a double asymmetric process has been devised. It constitutes a more general case of the very important enantioselective openings of meso-epoxides. Copyright
- Gansaeuer, Andreas,Fan, Chun-An,Keller, Florian,Keil, Jutta
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p. 3484 - 3485
(2008/01/01)
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- Engineering cytochrome P450 BM3 for terminal alkane hydroxylation
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Enzymes that catalyze the terminal hydroxylation of alkanes could be used to produce more valuable chemicals from hydrocarbons. Cytochrome P450 BM3 from Bacillus megaterium hydroxylates medium-chain fatty acids at subterminal positions at high rates. To engineer BM3 for terminal alkane hydroxylation, we performed saturation mutagenesis at selected active-site residues of a BM3 variant that hydroxylates alkanes. Recombination of beneficial mutations generated a library of BM3 mutants that hydroxylate linear alkanes with a wide range of regioselectivities. Mutant 77-9H exhibits 52% selectivity for the terminal position of octane. This regioselectivity is octane-specific and does not transfer to other substrates, including shorter and longer hydrocarbons or fatty acids. These results show that BM3 can be readily molded for regioselective oxidation.
- Meinhold, Peter,Peters, Matthew W.,Hartwick, Adam,Hernandez, Alisha R.,Arnold, Frances H.
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p. 763 - 772
(2007/10/03)
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- Photosensitive monomer
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This invention provides a compound of the formula (I): wherein R is hydrogen or C1-C4alkyl group; R′ is C1-C4alkyl group; n is an integer of 2, 3, 4, 5 or 6. The compound of formula (I) can be polymerized or copolymerized to form a photosensitive polymer or copolymer.
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- Ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid
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The ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid gives the corresponding ketones and alcohols highly efficiently at room temperature. The former catalytic system, RuCl2(PPh3)3-t-BuOOH, is preferable to the oxidation of alkylated arenes to give aryl ketones. The latter system, Ru/C-CH3CO3H, is suitable especially for the synthesis of ketones and alcohols from alkanes. The ruthenium-catalyzed oxidation of cyclohexane with CH3CO3H in trifluoroacetic acid/CH2Cl2 at room temperature gave cyclohexyl trifluoroacetate and cyclohexanone with 90% conversion and 90% selectivity (85:15). The mechanistic study indicates that these catalytic oxidations of hydrocarbons involve oxo-ruthenium species as key intermediates.
- Murahashi,Komiya,Oda,Kuwabara,Naota
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p. 9186 - 9193
(2007/10/03)
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- Decane autoxidation: Precursors of gamma lactones and other minor products
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Autoxidation of decane produces the following minor products in decreasing yields, viz. 2,5-, 3,6- and 4,7-decanediones and diols. Addition of 3-decanone to a decane autoxidation enhances the production of octanal, heptanal, octanoic and heptanoic acids. 3-Decanol initially inhibits the autoxidation reaction prior to being oxidized to 3-decanone. γ-Octanoic and γ-heptanoic lactone formation in the autoxidation of decane is promoted by the addition of 3- and 4-decyl hydroperoxides, respectively. These lactones are formed when tert-butoxy radicals react with 3,6- and 4,7-decane diols in the presence of oxygen. The nature of the intermediates in the formation of the minor products and the inhibition by alcohols are discussed.
- Goosen, Andre,Kindermans, Sybrandus
-
-
- Synthesis of new chiral catalysts, isoquinuclidinylmethanethiols, for the enantioselective addition of diethylzinc to aryl aldehydes
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New chiral ligands, isoquinuclidinylmethanethiols, were prepared and their catalytic abilities of asymmetric induction were examined in the addition of diethylzinc to aldehydes to furnish secondary alcohols in up to 94% ee.
- Nakano, Hiroto,Iwasa, Kazuto,Hongo, Hiroshi
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p. 267 - 274
(2007/10/03)
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- Arene-catalysed lithiation of triflates and triflamides under Barbier-type conditions: An indirect transformation of alcohols and amines into organolithium compounds
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The reaction of alkyl triflates 1 or benzyl triflamides 3 with an excess of lithium powder and a catalytic amount of naphthalene (4 mol%) in the presence of different electrophiles [Me3SiCl, Pr(i)CHO, Bu(t)CHO, PhCHO, 4-MeOC6H4-CHO, CH3(CH2)6CHO, Et2CO, (CH2)5CO, (c-C3H5)2CO, PhCOMe, 4-MeC6H4COPh, PhCh=NPh, n-C8H7CON(CH2)4] in THF at temperature ranging between -78 and 0°C leads, after hydrolysis with water, to the corresponding condensation products 2. When α,β-unsaturated carbonyl compounds are used as electrophilic compounds 1,2- (3-cyclohexenone) or 1,4-addition (cinnamaldehyde or benzylideneacetone) takes place depending on the electrophile used.
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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p. 14341 - 14348
(2007/10/03)
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- Highly regioselective reaction of zirconocene-alkene complexes with aldehydes or ketones
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Reactions of zirconocene-alkene complexes Cp2Zr(CH2=CHR)(PR'3) (R = H, Me, Et, SiR"3 or Ar) with aldehydes or ketones were investigated.Zirconocene-ethylene, -propylene or 1-butene complexes reacted with aldehydes or ketones at terminal carbons of alkenes to give the corresponding alcohols after hydrolysis with a high regioselectivity.A similar type of reaction product was also obtained by a reaction of zirconacyclopentanes with aldehydes.This reaction proceeded via β-β' carbon-carbon bond cleavage of zirconacyclopentanes.A reaction of zirconocene-vinylsilane complexes with ketones afforded 3-trimethylsilyl-1-oxa-2-zirconacyclopentanes with an excellent regioselectivity.Carbon-carbon bond formation occurred exclusively at the terminal carbon of vinylsilanes.Their corresponding γ-silylalcohols were obtained after hydrolysis.The products showed that vinylsilanes reacted with carbonyl compounds at the β-carbon to silyl group.It is in sharp contrast to the conventional reactions of vinylsilanes of which the α-carbon normally attacked electrophiles.The reactions of styrene and its derivatives with pentan-3-one on zirconium gave a mixture of two regioisomers.Substituents of alkenes tend to be in α-position to Zr in 1-oxa-2-zirconacyclopentanes.This orientation showed a different aspect of the formation of 1-oxa-2-zirconacyclopentanes from the alkene-alkene coupling reaction on zirconium.The regioselectivity of the reaction with carbonyl compounds decreased in this order; R = alkyl > silyl > aryl. Key words: Zirconium; Silicon; Metallocenes; Carbon-carbon bond formation; Aldehyde; Ketone
- Suzuki, Noriyuki,Rousset, Christophe J.,Aoyagi, Koichiro,Kotora, Martin,Takahashi, Tamotsu,et al.
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p. 117 - 128
(2007/10/02)
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- Zirconium Mediated Regioselective Carbon-Carbon Bond Formation Reactions
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Reactions of zirconocene-alkene complexes with aldehydes gave alcohols as coupling products after hydrolysis.The carbon-carbon bond formation proceeded at C1 carbon of alkenes, in sharp contrast to the reactions of alkene-alkene coupling on zirconium.A similar alcohol was also obtained by the reaction of zirconacyclopentane with aldehyde after hydrolysis.Treatment of (C5Me5)2ZrEt2 with styrene gave 2-phenylbutane after hydrolysis contrary to the case of Cp2ZrEt2 which afforded 1-phenylbutane.
- Takahashi, Tamotsu,Suzuki, Noriyuki,Hasegawa, Maki,Nitto, Yu,Aoyagi, Ko-ichiro,Saburi, Masahiko
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p. 331 - 334
(2007/10/02)
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- A new type of complex reagent, R4Pb / TiCl4
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Tetraalkllleads (R4Pb) reacted quite smoothly with aldehydes R'CHO in the presence of TiCl4 to produce the corresponding alcohols (RCHOHR′) in high to good yields. The reagent system, R4Pb/ TiCl4, exhibited high chemoselectivity; only aldehydes underwent the alkylation in the presence of ketones. Further, the new reagent exhibited high 1,2- and 1,3-asymmetric induction. The transfer order of alkyl groups in the reaction of aldehydes with mixed tetraalkylleads/TiCl4 was determined; Me>Et.i-Pr?n-Bu.
- Yamamoto, Yoshinori,Yamada, Jun-Ichi,Asano, Tetsuya
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p. 5587 - 5596
(2007/10/02)
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- The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
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Reduction of aldehydes with 2-propanol proceeded efficiently by catalysis with hydrous zirconium oxide to give the corresponding alcohols.Most ketones also were reduced efficiently, but conjugated or sterically hindered ketones resisted the reduction.The reduction was carried out with primary, secondary, or tertiary alcohols, and only secondary alcohols served as hydrogen donors.Kinetic experiments have indicated that the reaction rate is first-order dependence on each of the concentrations of the carbonyl compound, 2-propanol, and the catalyst.An observation of the primary isotope effect has suggested that a step of hydride transfer from absorbed 2-propanol to absorbed carbonyl compound constitutes the rate-determining step for the reduction.
- Shibagaki, Makoto,Takahashi, Kyoko,Matasushita, Hajime
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p. 3283 - 3288
(2007/10/02)
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- Vapor-Phase Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
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Vapor-phase reduction of aldehydes and ketones with 2-propanol was carried out over hydrous zirconium oxide.The reduction proceeded efficiently to give corresponding alcohols.The oxide worked continuously for 10 h without being inactivated.
- Shibagaki, Makoto,Takahashi, Kyoko,Kuno, Hideyuki,Kawakami, Hiroshi,Matsushita, Hajime
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p. 1633 - 1636
(2007/10/02)
-
- Novel Functionalized Organocopper Compounds by Direct Oxidative Addition of Zerovalent Copper to Organic Halides and Some of Their Reactions with Epoxides
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Reactions of epoxides with some unusually functionalized organocopper compounds generated from direct addition of zerovalent copper to organic halides are described.Organocopper reagents containing esters, nitriles, chlorides, and epoxides have been prepared.The first intramolecular cyclization via an epoxide cleavage process using the activated copper is also described.
- Wu, Tse-Chong,Wehmeyer, Richard M.,Rieke, Reuben D.
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p. 5057 - 5059
(2007/10/02)
-
- Shape Selective Alkane Hydroxylation by Metalloporphyrin Catalysts
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A series of manganese and iron porphyrins with sterically protected pockets are shown to be shape selective alkane hydroxylation catalysts.With iodosobenzene as oxidant, good regioselectivity is observed for hydroxylation of alkanes at the least hindered methyl group by using the very sterically hindered (5,10,15,20-tetrakis(2',4',6'-triphenylphenyl)porphyrinato)manganese(III) acetate (MnTTPPP(OAc)) as catalyst; The moderately hindered (5,10,15,20-tetrakis(2',4',6'-trimethoxyphenyl)porphyrinato)manganese(III) acetate shows little selectivity toward terminal CH3 hydroxylation but does show enhancement for the adjacent, ω - 1, CH2 site.Primary selectivity is dependent on the size and shape of the alkane substrate, with more bulky substituents giving greater primary selectivity.Substituting pentafluoroiodosobenzene or m-chloroperbenzoic acid as oxidants yields similar selectivity, thus conclusively demonstrating metal based oxidation via a common intermediate for these three systems.In contrast, tert-butyl hydroperoxide or 2,2,2-trifluoroethanol solubilized pentafluoroiodosobenzene show no primary carbon selectivity, and reaction product ratios are independent of the metalloporphyrin catalyst; this demonstrates that the site of oxidation with these oxidants is not metal based.The iron porphyrin derivatives also show good primary selectivity, although to a lesser degree than with the Mn derivatives, proving that these oxidations too are metal based.The regioselectivities for alkane hydroxilation shown by TTPPP derivatives are comparable to or better than those found for some isozymes of cytochrome P-450 which are responsible for primary alcohol biosynthesis from steroids, fatty acids, and alkanes.
- Cook, Bruce R.,Reinert, Thomas J.,Suslick, Kenneth S.
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p. 7281 - 7286
(2007/10/02)
-
- REDUCTION OF ALDEHYDES AND KETONES TO ALCOHOLS WITH HYDROUS ZIRCONIUM OXIDE AND 2-PROPANOL
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Reduction of aldehydes and ketones with 2-propanol was found to proceed efficiently in the presence of hydrous zirconium oxide.The reaction is performed simply and the products are easily isolated in the pure state by filtering off the hydrous zirconium oxide, followed by evaporation of solvents.
- Matsushita, Hajime,Ishiguro, Shigeo,Ichinose, Hiroshi,Izumi, Akira,Mizusaki, Shigenobu
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p. 731 - 734
(2007/10/02)
-
- Conversion of alkyl and aryl hydroxy compounds producing aldehyde, alcohol and ketone using manganese oxide/nickel oxide/magnesium oxide catalysts
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Alkyl and aryl hydroxy compounds are converted to aldehydes, alcohols, and ketones in the presence of hydrogen using a catalyst comprised of the oxides of manganese, nickel and magnesium.
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