9003-42-3Relevant academic research and scientific papers
Mechanistic Studies of the TRIP-Catalyzed Allylation with Organozinc Reagents
Hartmann, Peter E.,Lazzarotto, Mattia,Pletz, Jakob,Tanda, Stefan,Neu, Philipp,Goessler, Walter,Kroutil, Wolfgang,Boese, A. Daniel,Fuchs, Michael
, p. 9672 - 9679 (2020/09/03)
3,3-Bis(2,4,6-triisopropylphenyl)-1,1-binaphthyl-2,2-diyl hydrogenphosphate (TRIP) catalyzes the asymmetric allylation of aldehydes with organozinc compounds, leading to highly valuable structural motifs, like precursors to lignan natural products. Our previously reported mechanistic proposal relies on two reaction intermediates and requires further investigation to really understand the mode of action and the origins of stereoselectivity. Detailed ab initio calculations, supported by experimental data, render a substantially different mode of action to the allyl boronate congener. Instead of a Br?nsted acid-based catalytic activation, the chiral phosphate acts as a counterion for the Lewis acidic zinc ion, which provides the activation of the aldehyde.
Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone
Koyama, Minoru,Kawakami, Takafumi,Okazoe, Takashi,Nozaki, Kyoko
, p. 10913 - 10917 (2019/08/02)
Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield.
Switchable C-H Functionalization of N-Tosyl Acrylamides with Acryloylsilanes
Song, Shengjin,Lu, Ping,Liu, Huan,Cai, Sai-Hu,Feng, Chao,Loh, Teck-Peng
supporting information, p. 2869 - 2872 (2017/06/13)
A controllable Rh-catalyzed protocol to access alkylation and alkenylation-annulation of N-tosyl acrylamide with acryloyl silane is reported. In contrast to the directing group or catalyst-dependent divergent sp2 C-H alkylation/alkenylation, the intrinsic property of acryloylsilane allows the switchable reaction manifold, thereby affording either alkylation or annulation products with slight modification of the reaction conditions.
A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
, p. 420 - 430 (2015/12/31)
α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
Rhodium(iii)-catalyzed C-H allylation of electron-deficient alkenes with allyl acetates
Feng, Chao,Feng, Daming,Loh, Teck-Peng
supporting information, p. 342 - 345 (2015/01/09)
Rhodium-catalyzed C-H allylation of acrylamides with allyl acetates is reported. The use of weakly coordinating directing group resulted in high reaction efficiency, broad functionality tolerance and excellent γ-selectivity, which opens a new synthetic pathway for the access of 1,4-diene skeletons.
Direct ortho-thiolation of arenes and alkenes by nickel catalysis
Lin, Cong,Li, Danyang,Wang, Binjie,Yao, Jinzhong,Zhang, Yuhong
supporting information, p. 1328 - 1331 (2015/03/14)
The direct thiolation of arenes and alkenes with diaryl disulfides was developed by nickel catalysis. The reaction displayed exceptional compatibility with a wide range of functional groups to regioselectively give the diaryl sulfides and alkenyl sulfides in high yields.
Aerobic oxidative esterification of aldehydes with alcohols by gold-nickel oxide nanoparticle catalysts with a core-shell structure
Suzuki, Ken,Yamaguchi, Tatsuo,Matsushita, Ken,Iitsuka, Chihiro,Miura, Junichi,Akaogi, Takayuki,Ishida, Hiroshi
, p. 1845 - 1849 (2013/09/02)
Oxidative esterification of aldehydes with alcohols proceeds with high efficiency in the presence of molecular oxygen on supported gold-nickel oxide (AuNiOx) nanoparticle catalysts. The method is environmentally benign because it requires only molecular oxygen as the terminal oxidant and gives water as the side product. The AuNiOx nanoparticles have a core-shell structure, with the Au nanoparticles at the core and the surface covered by highly oxidized NiOx. Aerobic oxidative esterification of methacrolein in methanol to methyl methacrylate is an important industrial method for the production of polymethyl methacrylate.
METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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Paragraph 0024; 0026, (2013/11/19)
A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
H-transfer reaction during decomposition of N-(2-methylpropyl)- N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines
Edeleva, Mariya,Marque, Sylvain R.A.,Kabytaev, Kuanish,Guillaneuf, Yohann,Gigmes, Didier,Bagryanskaya, Elena
, p. 1323 - 1336 (2013/04/10)
Thermal decomposition of four tertiary N-(2-methylpropyl)-N-(1- diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines (SG1-C(Me)2-C(O)-OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using 1/su
Dependence of thermal stability on molecular structure of RAFT/MADIX agents: A kinetic and mechanistic study
Zhou, Yanwu,He, Junpo,Li, Changxi,Hong, Linxiang,Yang, Yuliang
experimental part, p. 8446 - 8457 (2012/03/12)
The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., β-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the β-elimination of thiocarbonylthio compounds possessing β-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more β-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) -CH2Ph (5) > -PS (PS-RAFT 15) > -C(Me)HPh (2) > -C(Me)2C(=O)OC2H5 (7) > -C(Me)2Ph(1) > -PMMA (PMMA-RAFT 16) > -C(Me) 2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > -N(CH2CH3)2 (13) > -SCH(CH3)Ph (8) > -Ph (2) > -CH2Ph (4) > -PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated.
