7462-67-1Relevant academic research and scientific papers
Highly enantioselective epoxidation of olefins by H2O2 catalyzed by a non-heme Fe(ii) catalyst of a chiral tetradentate ligand
Mitra, Mainak,Cusso, Olaf,Bhat, Satish S.,Sun, Mingzhe,Cianfanelli, Marco,Costas, Miquel,Nordlander, Ebbe
supporting information, p. 6123 - 6131 (2019/05/16)
The chiral tetradentate N4-donor ligand, 1-methyl-2-({(S)-2-[(S)-1-(1-methylbenzimidazol-2-yl methyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl) benzimidazole (S,S-PDBzL), based on a chiral dipyrrolidine backbone, has been synthesized and its corresponding Fe(ii) complex has been prepared and characterized. The X-ray structure of the complex reveals that the Fe(ii) ion is in a distorted octahedral coordination environment with two cis-oriented coordination sites occupied by (labile) triflate anions. The ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results indicate that the Fe(ii) complex is capable of effecting comparatively high enantioselectivities (>80%) in the epoxidation reactions.
Visible-Light-Promoted Photoredox Syntheses of α,β-Epoxy Ketones from Styrenes and Benzaldehydes under Alkaline Conditions
Li, Jing,Wang, David Zhigang
supporting information, p. 5260 - 5263 (2015/11/18)
A range of styrenes and benzaldehydes were smoothly combined to form α,β-epoxy ketones under the synergistic actions of photocatalyst Ru(bpy)3Cl2, tert-butyl hydroperoxide (t-BuOOH), cesium carbonate (Cs2CO3), and visible light irradiation. The process likely proceeds through visible-light-enabled photocatalytic generations of acyl radicals as key intermediates.
Asymmetric epoxidation with H2O2 by manipulating the electronic properties of non-heme iron catalysts
Cusso, Olaf,Garcia-Bosch, Isaac,Ribas, Xavi,Lloret-Fillol, Julio,Costas, Miquel
supporting information, p. 14871 - 14878 (2013/10/22)
A non-heme iron complex that catalyzes highly enantioselective epoxidation of olefins with H2O2 is described. Improvement of enantiomeric excesses is attained by the use of catalytic amounts of carboxylic acid additives. Electronic effects imposed by the ligand on the iron center are shown to synergistically cooperate with catalytic amounts of carboxylic acids in promoting efficient O-O cleavage and creating highly chemo-and enantioselective epoxidizing species which provide a broad range of epoxides in synthetically valuable yields and short reaction times.
Iron-catalyzed carbonylation-peroxidation of alkenes with aldehydes and hydroperoxides
Liu, Weiping,Li, Yuanming,Liu, Kaisheng,Li, Zhiping
, p. 10756 - 10759 (2011/08/22)
A three-component reaction of alkenes, aldehydes, and hydroperoxides catalyzed by FeCl2 to β-peroxy ketones has been achieved. This three-component reaction can be also applied to the synthesis of α-carbonyl epoxides, through either a stepwise base-induced epoxidation of the separated β-peroxy ketone products or a one-pot process by simply adding base to the reaction mixture after the completion of the three-component reaction.
Stereoselective synthesis of 3,5-dialkyl-3,5-dihydro-3,5-diphenyl-4H- pyrazol-4-ones
Moiseev, Andrey G.,Neckers, Douglas C.
, p. 2901 - 2905 (2007/10/03)
We report stereoselective five-step syntheses of cis-3-ethyl-3,5-dihydro-3, 5-diphenyl-5-methyl-4H-pyrazol-4-one (cis-1b) and trans-3,5-diethyl-3,5-dihydro- 3,5-diphenyl-4H-pyrazol-4-one (trans-1c). The key synthon was 1,3-diphenylpent-2-en-1-one (5b) synthesized in a new one-pot crossed aldol/dehydration reaction of acetophenone with propiophenone using titanium(IV) chloride/tributylamine, followed by treatment with methanesulfonyl chloride and triethylamine. Georg Thieme Verlag Stuttgart.
Synthesis, Structure, and Sterreoselective Reaction of a Chiral Hydroxy-Stabilized Metal-Free Enolate
Reetz, Manfred T.,Huette, Stephan,Goddard, Richard,Robyr, Chantal
, p. 382 - 384 (2007/10/03)
The reaction of acetophenone with tetrabutylammonium hydroxide affords the tetrabutylammonium enolate of phenyl (2-hydroxy-2-phenyl)propyl ketone.The crystal structure of this chiral enolate shows intramolecular hydrogen bonding between the hydroxyl group and the enolate oxygen atom.Furthermore, the α-methylene units of the ammonium counterion form hydrogen bonds to the basic enolate C and O atoms and to the O atom of the hydroxy group.This three-point bonding occurs selectively on the Re,Re side, a phenomenon which may be responsible for the direction of diastereoselectively in the epoxide-forming reaction of the enolate with N-bromosuccinimide. - Keywords: asymmetric synthesis; chirality; enolates; hydrogen bonds; structure elucidation
Exploratory Study on Photoinduced Single Electron Transfer Reactions of α,β-Epoxy Ketones with Amines
Hasegawa, Eietsu,Ishiyama, Kenyuki,Horaguchi, Takaaki,Shimizu, Takahachi
, p. 1631 - 1635 (2007/10/02)
Photoinduced single electron transfer (SET) reactions of α,β-epoxy ketones have been studied using alkylamine electron donors.Irradiation of chalcone epoxide 1 with triethylamine (TEA) afforded β-diketone 2 and β-hydroxy ketne 3.Photoreaction of 1 with TEA in MeOH resulted in a slightly increased product ratio (3/2) compared with that in MeCN.When 1,4-diazabicyclooctane (DABCO) was used instead of TEA, a decrease in the yield of 3 was observed.Only 2 was obtained on irradiation of a solution of 1 in TEA and MeCN containing LiClO4.Studies of photoreactions of dypnone epoxide 9, benzoylisopropylethylene epoxide 12, and acrylophenone epoxide 15 indicate that the nature of β-substituent also influences the product distribution.It was also found that 1,6-bis(dimethylamino)pyrene (BDMAP) sensitizes the photoreaction of 1 in the presence of TEA to produce 2.Based on the results obtained, a reaction mechanism involving selective Cα-O bond cleavage of intermediate α,β-epoxy ketone anion radicals is proposed.
Kinetics of Epoxidation of α,β-Unsaturated Ketones in Methanol Medium
Rama Rao, D. Sri
, p. 786 - 789 (2007/10/02)
The kinetics of epoxidation of α,β-unsaturated ketones by alkaline H2O2 in methanol in the temperature range 25-40 deg C has been studied.The addition follows second order kinetics.The results indicate that the concentration of NaOH has a significant effect on the reactivity.The effect of various substituents in these reactions show that electron-releasing groups attached to the β-carbon atom in the olefin diminish the rate and electron-attracting groups enhance it.The oxidative cleavage of a few substituted epoxychalkones by hydroperoxide anion has also been studied in methanol at 30 deg C.Adherence to second order kinetics is excellent in every case and the rates are slower than those of the corresponding chalkones.The stability of epoxides depends on the substituents; electron-releasing groups diminish the rate and electron-attracting groups enhance it as observed in the case of epoxidation.The reaction obeys the Arrhenius equation and the respective activation parameters have been calculated.The effect of solvent polarity on the rate of epoxidation has been studied.The differences in the rates in methanol and water as solvents have been explained on the basis of solvent-solute interaction.
