597-96-6Relevant articles and documents
Palladium-Catalyzed C(sp3)?H Arylation of Primary Amines Using a Catalytic Alkyl Acetal to Form a Transient Directing Group
St John-Campbell, Sahra,Ou, Alex K.,Bull, James A.
supporting information, p. 17838 - 17843 (2018/11/23)
C?H Functionalization of amines is a prominent challenge due to the strong complexation of amines to transition metal catalysts, and therefore typically requires derivatization at nitrogen with a directing group. Transient directing groups (TDGs) permit C?H functionalization in a single operation, without needing these additional steps for directing group installation and removal. Here we report a palladium catalyzed γ-C?H arylation of amines using catalytic amounts of alkyl acetals as transient activators (e.g. commercially available (2,2-dimethoxyethoxy)benzene). This simple additive enables arylation of amines with a wide range of aryl iodides. Key structural features of the novel TDG are examined, demonstrating an important role for the masked carbonyl and ether functionalities. Detailed kinetic (RPKA) and mechanistic investigations determine the order in all reagents, and identify cyclopalladation as the turnover limiting step. Finally, the discovery of an unprecedented off-cycle free-amine directed ?-cyclopalladation of the arylation product is reported.
Hydroperoxidation of alkanes with hydrogen peroxide catalyzed by aluminium nitrate in acetonitrile
Mandelli, Dalmo,Chiacchio, Karyna C.,Kozlov, Yuriy N.,Shul'pin, Georgiy B.
scheme or table, p. 6693 - 6697 (2009/04/07)
The first example of alkane oxygenation with hydrogen peroxide catalyzed by a non-transition metal derivative (aluminium) is reported. Heating (70 °C) a solution of an alkane, RH, hydrogen peroxide (70% aqueous) and a catalytic amount of Al(NO3)3·9H2O in air for a few hours afforded the corresponding alkyl hydroperoxide, ROOH. With cyclooctane, the hydroperoxide yield attained 31% and the maximum turnover number was 150. It is proposed on the basis of measurements of the selectivity parameters for the oxidation of linear and branched alkanes and a kinetic study that the oxidation occurs with the participation of hydroxyl radicals.
Study of syntheses and specific rotations of (S)-3-phenylhexan-3-ol and its derivatives
Liao, Tou-Gen,Ren, Jie,Fan, Hua-Fang,Xie, Ming-Jin,Zhu, Hua-Jie
, p. 808 - 815 (2008/09/21)
Tertiary alcohols, 3-phenylhexan-3-ol and 3-methylhexane-3-ol, and their derivatives were synthesized. The reaction conditions of the esterification of the tertiary alcohol with 2-NO2PhCO2Cl and 4-NO2PhCO2Cl were optimized. The absolute configuration of the derivative from (S)-3-phenylhexan-3-ol was identified by X-ray study and computational methods. Experimental results confirmed the computational specific rotation predictions by DFT-based and matrix methods.
Oxidations catalyzed by osmium compounds. Part 1: Efficient alkane oxidation with peroxides catalyzed by an olefin carbonyl osmium(0) complex
Shul'pin, Georgiy B.,Kudinov, Aleksandr R.,Shul'pina, Lidia S.,Petrovskaya, Elena A.
, p. 837 - 845 (2007/10/03)
A carbonyl osmium(0) complex with π-coordinated olefin, (2,3-η-1,4-diphenylbut-2-en-1,4-dione)undecacarbonyl triangulotriosmium (1), efficiently catalyzes oxygenation of alkanes (cyclohexane, cyclooctane, n-heptane, isooctane, etc.) with hydrogen peroxide, as well as with tert-butyl hydroperoxide and meta-chloroperoxybenzoic acid in acetonitrile solution. Alkanes are oxidized to corresponding alcohols, ketones (aldehydes) and alkyl hydroperoxides. Thus, heating cyclooctane with the 1-H2O2 combination at 70 °C gave products with turnover number as high as 2400 after 6 h. The maximum obtained yield of all products was equal to 20% based on cyclohexane and 30% based on H2O2. The oxidation of linear and branched alkanes exhibits very low regio- and bond-selectivity parameters and this testifies that the reaction proceeds via attack of hydroxyl radicals on C-H bonds of the alkane. The oxygenation products were not formed when the reaction was carried out under argon atmosphere and it can be thus concluded that the oxygenation occurs via the reaction between alkyl radicals and atmospheric oxygen. In summary, the Os(0) complex is much more powerful generator of hydroxyl radicals than any soluble derivative of iron (which is an analogue of osmium in the Periodic System).
Alkane oxygenation with H2O2 catalysed by FeCl 3 and 2,2′-bipyridine
Shul'pin, Georgiy B.,Golfeto, Camilla C.,Süss-Fink, Georg,Shul'pina, Lidia S.,Mandelli, Dalmo
, p. 4563 - 4567 (2007/10/03)
The H2O2-FeCl3-bipy system in acetonitrile efficiently oxidises alkanes predominantly to alkyl hydroperoxides. Turnover numbers attain 400 after 1 h at 60°C. It has been assumed that bipy facilitates proton abstraction from a H2O2 molecule coordinated to the iron ion (these reactions are stages in the catalytic cycle generating hydroxyl radicals from the hydrogen peroxide). Hydroxyl radicals then attack alkane molecules finally yielding the alkyl hydroperoxide.
Alkane oxygenation catalysed by gold complexes
Shul'Pin, Georgiy B.,Shilov, Alexander E.,Süss-Fink, Georg
, p. 7253 - 7256 (2007/10/03)
Gold(III) and gold(I) complexes, NaAuCl4 and ClAuPPh3, efficiently catalyse the oxidation of alkanes by H2O2 in acetonitrile solution at 75°C. Turnover numbers (TONs) attain 520 after 144 h. Alkyl hydroperoxides are the main products, whereas ketones (aldehydes) and alcohols are formed in smaller concentrations. It is suggested on the basis of the bond selectivity study that at least one of the pathways in Au-catalysed alkane hydroperoxidation does not involve the participation of free hydroxyl radicals. Possibly, the oxidation begins from the alkane hydrogen atom abstraction by a gold oxo species. The oxidation of cyclooctane by air at room temperature catalysed by NaAuCl4 in the presence of Zn/CH3COOH as a reducing agent and methylviologen as an electron-transfer agent gave cyclooctanol (TON=10).
Oxidations by the system 'hydrogen peroxide-manganese(IV) complex- acetic acid' - Part II: Hydroperoxidation and hydroxylation of alkanes in acetonitrile
Shul'pin, Georgiy B.,Suess-Fink, Georg,Lindsay Smith, John R.
, p. 5345 - 5358 (2007/10/03)
Higher alkanes (cyclohexane, n-pentane, n-heptane, methylbutane, 2- and 3-methylpentanes, 3-methylhexane, cis- and trans-decalins) are oxidized at 20 °C by H2O2 in air in acetonitrile (or nitromethane) solution in the presence of the manganese(IV) salt [L2Mn2O3](PF6)2 (L = 1,4,7-trimethyl- 1,4-7-triazacyclononane) as the catalyst. An obligatory component of the reaction mixture is acetic acid. Turnover numbers attain 3300 after 2 h, the yield of oxygenated products is 46% based on the alkane. The oxidation affords initially the corresponding alkyl hydroperoxide as the predominant product, however later these compounds decompose to produce the corresponding ketones and alcohols. Regio- and bond selectivities of the reaction are high: C(1): C(2): C(3): C(4) ? 1: 40: 35: 35 and 1°: 2°: 3°is 1: (15-40): (180-300). The reaction with both isomers of decalin gives (after treatment with PPh3) alcohols hydroxylated in the tertiary positions with the cis/trans ratio of ~2 in the case of cis-decalin, and of ~30 in the case of trans-decalin (i.e. in the latter case the reaction is stereospecific). Light alkanes (methane, ethane, propane, normal butane and isobutane) can be also easily oxidized by the same reagent in acetonitrile solution, the conditions being very mild: low pressure (1-7 bar of the alkane) and low temperature (- 22 to +27°C). Catalyst turnover numbers attain 3100, the yield of oxygenated products is 22% based on the alkane. The yields of oxygenates are higher at low temperatures. The ratio of products formed (hydroperoxide: ketone: alcohol) depends very strongly on the conditions of the reaction and especially on the catalyst concentration (at higher catalyst concentration the ketone is predominantly produced).
Molybdenum-catalyzed epoxidations of oct-1-ene and cyclohexene with organic hydroperoxides: Steric effects of the alkyl substituents of the hydroperoxide on the reaction rate
Lempers,Van Crey,Sheldon
, p. 542 - 546 (2007/10/03)
A kinetic study of the epoxidation of oct-1-ene and cyclohexene with alkyl hydroperoxides is reported. The alkyl hydroperoxides were obtained in a moderate to high purity from the corresponding alcohols by acid-catalyzed exchange with hydrogen peroxide. The reaction rates in pseudo first-order experiments of these olefins with various alkyl hydroperoxides strongly depend on the structure of the alkyl group of the alkyl hydroperoxide. When one of the methyl groups in tert-butyl hydroperoxide (TBHP, 4a) is substituted by an alkyl group, R, the reaction rate decreases in the order Et > Pr > Bu > t BuCH2 > tBu. Substitution of two methyl groups of TBHP as in 1-ethyl-1-methylpropyl hydroperoxide (5a) and 1-ethyl-1-methylbutyl hydroperoxide (5b) showed a further decrease in reaction rate of epoxidation. When all three methyl groups are substituted by, for example, three ethyl groups as in 1,1-diethylpropyl hydroperoxide (6a) a decrease of approximately 99% in reaction rate is observed. Introduction of a ring system in the hydroperoxide such as in cyclohexyl hydroperoxide (3), 1-methyl-cyclohexyl hydroperoxide (2) and pinane hydroperoxide (1) also showed a dramatic decrease in reaction rate of epoxidation. An investigation of relative rates of epoxidation in competition experiments of cyclohexene and hex-1-ene with 1-tert-butylcyclohexene with different alkyl hydroperoxides also showed them to depend on the structure of the alkyl group of the alkyl hydroperoxide. These results are rationalized on the basis of a mechanism involving nucleophilic attack of the olefin on an alkylperoxomolybdenum(VI) intermediate. Bulky substituents at the α-position in the alkyl hydroperoxide can seriously impede the approach of the olefin to the O-O bond.
Hindered organoboron groups in organic chemistry. 28 The solvolyses of bis(2,6-dimethyl-4-methoxyphenyl)organylboranes, (DMP)2BR
Pelter, Andrew,Drake, Robert
, p. 13801 - 13828 (2007/10/02)
Mineral acid catalysed methanolysis of bis (2,6-dimethyl-4-methoxyphenyl)organylboranes (DMP)2BR, (1), is much faster than that of the corresponding dimesitylorganylboranes, MeS2BR. This allows for the release of organyl groups from 'overhindred' boranes. It also provides a link between (DMP)2BR, from which α-carbanions can be produced, and RB(OMe)2 which do not yield α-carbanions. Solvolyses can be enhanced by the use of glycol, which renders even acetic acid on effective solvolyses catalyst.
Resolution of secondary alcohols by enzyme-catalyzed transesterification in alkyl carboxylates as the solvent
Janssen,Klunder,Zwanenburg
, p. 7645 - 7662 (2007/10/02)
The Porcine Pancreatic Lipase (PPL)- and Mucor Esterase-catalyzed resolution of 1-phenylethanol 5 in four different alkyl carboxylate solvents, viz. methyl acetate, propionate and butyrate and ethyl acetate, was evaluated. The beneficial influence of the addition of molecular sieves 4A to the reaction mixture is demonstrated. A Mucor Esterase-catalyzed resolution of 5 on a 0.5 mol scale is described. The kinetic resolution of a large variety of secondary alcohols (5 - 22b) was investigated using both biocatalysts under the established optimal reaction conditions for substrate 5.
