71964-68-6Relevant academic research and scientific papers
Aerobic Oxidative Dehydrogenation of Ketones to 1,4-Enediones
Zhao, Bao-Yin,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
supporting information, p. 1216 - 1221 (2021/02/20)
An efficient and unprecedented strategy for the synthesis of 1,4-enediones from saturated ketones has been developed via palladium-catalyzed oxidative dehydrogenation. The protocol employs molecular oxygen as the sole oxidant and represents an atom- and step-economic process. The approach showed broad substrate scope, good functional group tolerance, and complete E-stereoselectivity. The reaction mechanism has been investigated through deuterium-labeling experiments and intermediate experiments.
The mechanism for the rhodium-catalyzed decarbonylation of aldehydes: A combined experimental and theoretical study
Fristrup, Peter,Kreis, Michael,Palmelund, Anders,Norrby, Per-Ola,Madsen, Robert
, p. 5206 - 5215 (2008/12/22)
The mechanism for the rhodium-catalyzed decarbonylation of aldehydes was investigated by experimental techniques (Hammett studies and kinetic isotope effects) and extended by a computational study (DFT calculations). For both benzaldehyde and phenyl acetaldehyde derivatives, linear Hammett plots were obtained with positive slopes of +0.79 and +0.43, respectively, which indicate a buildup of negative charge in the selectivity-determining step. The kinetic isotope effects were similar for these substrates (1.73 and 1.77 for benzaldehyde and phenyl acetaldehyde, respectively), indicating that similar mechanisms are operating. A DFT (B3LYP) study of the catalytic cycle indicated a rapid oxidative addition into the C(O)-H bond followed by a rate-limiting extrusion of CO and reductive elimination. The theoretical kinetic isotope effects based on this mechanism were in excellent agreement with the experimental values for both substrates, but only when migratory extrusion of CO was selected as the rate-determining step.
Incorporation of deuterium-labelled analogs of isopentenyl diphosphate for the elucidation of the stereochemistry of rubber biosynthesis
Scholte, Andrew A.,Vederas, John C.
, p. 730 - 742 (2007/10/03)
A series of six deuterium-labelled analogs of isopententyl diphosphate (IPP) was prepared to investigate the detailed stereochemical course of addition of C5 units during rubber biosynthesis in Hevea brasiliensis and Parthenium argentatum. These analogs were incorporated into the cis-polyisoprene chain by rubber transferase in rubber particles, and the stereochemistry was determined by 2H-NMR analysis of the polymer or of levulinic acid derivatives obtained from its ozonolytic degradation. Results indicate that rubber chain elongation occurs with loss of the pro-S hydrogen of IPP, addition of the allylic diphosphate to the si face of IPP and inversion of stereochemistry at the carbon bearing the diphosphate. The Royal Society of Chemistry.
Stereochemistry of 2-phenylethylamine oxidation catalyzed by bacterial copper amine oxidase
Uchida, Mayumi,Ohtani, Akifumi,Kohyama, Naoki,Okajima, Toshihide,Tanizawa, Katsuyuki,Yamamoto, Yukio
, p. 2664 - 2667 (2007/10/03)
The stereochemical course of the reaction catalyzed by a copper amine oxidase from Arthrobacter globiformis has been investigated using 2-phenylethylamine stereospecifically deuterium-labeled at the C1 position. Measurements of deuterium content in the product, phenylacetaldehyde, by gas chromatography-mass spectrometry revealed stereospecific abstraction of the pro-S hydrogen during the enzymatic oxidation, as predicted from the structure modeling for the enzyme-bound substrate.
The first rhodium-catalyzed anti-markovnikov hydroamination: Studies on hydroamination and oxidative amination of aromatic olefins
Beller,Trauthwein,Eichberger,Breindl,Herwig,Mueller,Thiel
, p. 1306 - 1319 (2007/10/03)
The first transition-metal-catalyzed regiospecific anti-Markovnikov hydroamination of aromatic olefins is reported. Styrene and substituted styrenes react with secondary aliphatic amines, especially morpholine and Narylpiperazines, in the presence of cationic rhodium complexes to give 2- aminoethenylbenzene and 2-aminoethylbenzene derivatives. Cationic [Rh(cod)2]+BF4- and various phosphines (l:2-mixture) were employed as in situ catalysts. According to labeling experiments, there is no evidence that the hydroamination is a consecutive hydrogenation of a previously formed enamine. Hydroamination with simple secondary amines, for example piperidine, can also be achieved by the use of a higher olefin concentration and higher reaction temperatures than those given in previously published reaction procedures. Kinetic investigations of the major reaction pathway reveal that the reaction rate of the oxidative amination and the hydroamination is dependent on the styrene and on the catalyst concentration, and independent of the amine concentration. Experiments that employed deuterium-labeled amines (N-D) provided evidence that the mechanism involves an amine- activating pathway. The substituents on the styrene, the phosphine ligand, and the solvent influence the yield of the aminations and the enamine:alkylamine ratio.
Tropic acid biosynthesis: The incorporation of (RS)-phenyl[2-18O,2-2H]lactate into littorine and hyoscyamine in Datura stramonium
Wong, Chi W.,Hamilton, John T. G.,O'Hagan, David,Robins, Richard J.
, p. 1045 - 1046 (2007/10/03)
The incorporation of oxygen-18 from (RS)-phenyl-[2-18O,2-2H]lactate into the tropane alkaloids littorine 1 and hyoscyamine 2 in Datura stramonium reveals that up to 29% of the oxygen-18 is lost during the transformation of 1 to 2.
A mechanistic model for the selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid
Corey,Palani, Anandan
, p. 7945 - 7948 (2007/10/02)
The selective oxidation of 1,4-diols to γ-lactols by o-iodoxybenzoic acid occurs by a rate-limiting carbonyl-forming elimination pathway in which the carbinol proton is abstracted internally via a six-atom cyclic arrangement, which explains the observed selectivity.
Halogen-exchange reactions between alkyl fluorides and boron trihalides or tetrahalides. A convenient synthesis of alkyl halides from alkyl fluorides
Namavari, Mohammad,Satyamurthy, N.,Barrio, Jorge R.
, p. 89 - 93 (2007/10/02)
A simple and effective method for converting fluoroalkanes to their corresponding chloro-, bromo- and iodo-alkanes using commercially available boron trihalides and titanium tetrahalides is described. - Keywords: Halogen-exchange reactions; Alkyl fluorides; Boron trihalides; Titanium tetrahalides; NMR spectroscopy; Mass spectrometry
DIASTEREOTOPIC SELECTION OF C2 HYDROGENS IN THE REARRANGEMENT OF C1-SUBSTITUTED EPOXIDES: AN EXAMINATION OF STYRENE OXIDE
Coxon, J. M.,McDonald, D. Q.
, p. 2575 - 2576 (2007/10/02)
Rearrangement of styrene oxide with (a) LiClO4 and (b) BF3 to give phenylethanal exhibits diastereotopic selection with migration of the hydrogen trans to the phenyl group being favoured 1.4 and 1.14 times respectively.The rate of rotation about the C1-C2
Oxygenation of Styrene by Cytochrome P-450 Model Systems: A Mechanistic Study
Collman, James P.,Kodadek, Thomas,Brauman, John I.
, p. 2588 - 2594 (2007/10/02)
The manganese and iron porphyrin catalyzed oxygenation of styrene results in the production of phenylacetaldehyde as well as the expected epoxide.It is demonstrated that aldehyde is a primary product and dose not result from isomerization of styrene oxide.Isotope labeling studies show that one of the β hydrogen atoms of styrene migrates to the benzylic carbon in the course of aldehyde formation.Experiments using cis and trans deuterated styrenes reveal that there is a stereoelectronic preference for migration of the hydrogen cis to the aromatic ring.Styrene, styrene-d8, and cis-β-deuteriostyrene yield similar ratios of epoxide to aldehyde, indicating that β hydrogen migration occurs after the rate-determining step for formation of phenylacetaldehyde.The mechanism of this rearrangement is discussed.Some new information concerning the mechanism of olefin epoxidation by these catalysts is also presented.These results may have relevance to the mechanism of alkene oxygenation by the cytochrome P-450 monooxygenase enzymes.
