61840-95-7Relevant academic research and scientific papers
Peroxide- And transition metal-free electrochemical synthesis of α,β-epoxy ketones
Zhang, Mengxun,Chen, Tie,Fang, Shisong,Wu, Weihua,Wang, Xin,Wu, Haiqiang,Xiong, Yongai,Song, Jun,Li, Chenyang,He, Zhendan,Lee, Chi-Sing
supporting information, p. 2481 - 2486 (2021/04/02)
A novel electrochemical method for the synthesis of α,β-epoxy ketones is reported. With KI as the redox mediator, methyl ketones reacted with aldehydes under peroxide- and transition metal-free electrolytic conditions and afforded α,β-epoxy ketones in one pot (36 examples, 52-90% yield). This safe and environmental-friendly method has a broad substrate scope and can readily provide a variety of α,β-epoxy ketones in gram-scales for evaluation of their anti-cancer activities.
Asymmetric epoxidation of α,β-unsaturated ketones via an amine-thiourea dual activation catalysis
Zhang, Lu-Wen,Wang, Li,Ji, Nan,Dai, Si-Yang,He, Wei
supporting information, (2021/03/15)
A simple asymmetric epoxidation method is developed to effectively synthesize chiral α-carbonyl epoxides through an amine-thiourea dual activation catalysis. In this method, TBHP, as an oxidant, determined the reaction rate, and the chiral amine-thiourea catalyst effectively controlled the stereoselectivity of the reaction, and KOH promoted deprotonation. 22 examples of α,β-unsaturated ketones with various substituent groups are smoothly converted into α-carbonyl epoxides with moderate to excellent enantiomeric excess.
Asymmetric synthesis of new γ-butenolides: Via organocatalyzed epoxidation of chalcones
Vieira, Lucas C. C.,Matsuo, Bianca T.,Martelli, Lorena S. R.,Gall, Mayara,Paix?o, Marcio W.,Corrêa, Arlene G.
supporting information, p. 6098 - 6103 (2017/08/02)
γ-Butenolides have been recognized as an important structural framework in a number of natural products and medicinally important agents. In this work we describe a new metal-free sequential strategy for the asymmetric synthesis of substituted γ-butenolides having epoxychalcones as the advanced intermediate. Using the optimized reaction conditions, we were able to carry out the three-step sequence, epoxidation, olefination and hydrolysis, with only one single chromatographic purification of the final product, furnishing new enantiomerically enriched γ-butenolides in moderate overall yield and good enantiomeric excess.
Enantioselective Epoxidation of Electron-Deficient Alkenes Catalyzed by Manganese Complexes with Chiral N4 Ligands Derived from Rigid Chiral Diamines
Chen, Xiangning,Gao, Bao,Su, Yijin,Huang, Hanmin
supporting information, p. 2535 - 2541 (2017/08/16)
A series of tetradentate sp2N/sp3N hybrid chiral N4 ligands derived from rigid chiral diamines were synthesized, which enabled the first manganese-catalyzed enantioselective epoxidation of electron-deficient alkenes with hydrogen peroxide (H2O2) as an oxidant. The reaction furnishes enantiomerically pure epoxy amides, epoxy ketones as well as epoxy esters in good yields and excellent enantioselectivities (up to 99.9% ee) with lower catalyst loading. Preliminary studies on structure–activity relationship demonstrated that maintaining comparatively lower electron-donating ability of the sp3N and relatively higher electron-donating ability of sp2N of the N4 ligands is beneficial to getting higher activity and selectivity, thus providing us a new view to understand epoxidation with H2O2. (Figure presented.).
Asymmetric epoxidation of substituted chalcones and chalcone analogues catalyzed by α-d-glucose- and α-d-mannose-based crown ethers
Mako, Attila,Rapi, Zsolt,Keglevich, Gyoergy,Szoellsy, Aron,Drahos, Laszlo,Hegeds, Laszlo,Bako, Peter
experimental part, p. 919 - 925 (2010/08/06)
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chalcone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselectivities (62-83% ee) were found in the case of ortho-substituted model compounds. The highest ee values (ee of 83-97%) were obtained in the case of para-substituted models. From among the chalcone analogues, the maximum ee (90-92%) was detected for the model compound having α-tert-butyl- and β-aryl groups. Using glucose-based crown ether 1, formation of the (-)-enantiomer was preferred, while applying mannose-based 2 as the catalyst, the (+)-enantiomer was in excess.
Circular dichroism spectra of trans-chalcone epoxides
Pal, Krisztina,Kallay, Mihaly,Kubinyi, Miklos,Bako, Peter,Mako, Attila
, p. 1521 - 1528 (2008/02/11)
The electronic absorption and CD spectra of (-)-trans-chalcone epoxide and its derivatives with methyl and alkoxy substituents at the ortho-positions of the aromatic rings have been measured. The spectra have been assigned with help of the energies, oscillatory strengths, and rotatory strengths of the singlet transitions obtained from DFT calculations. The features of the CD spectra, indicative of the absolute configuration, are the carbonyl n-π* band and two further strong bands assigned to the overlapping signals of π-π* and nepoxy-π* excitations.
Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by silica-grafted poly-(L)-leucine catalysts
Yi, Hua,Zou, Gang,Li, Qiang,Chen, Qun,Tang, Jie,He, Ming-Yuan
, p. 5665 - 5668 (2007/10/03)
A practical procedure has been developed for grafting poly(amino acid) on silica gel as an efficient and recoverable catalyst in the Juliá-Colonna asymmetric epoxidation with high enantioselectivities. Separation and recovery of the catalyst of poly(amino
Synthetic Enzymes. Part 2. Catalytyc Asymmetric Epoxidation by means of Polyamino-acids in a Triphase System
Julia, Sebastian,Guixer, Joan,Masana, Jaume,Rocas, Jose
, p. 1317 - 1324 (2007/10/02)
The asymmetric epoxidation of several chalcones and other electron-poor olefins, in the presence of catalytic amounts of poly-(S)-amino-acids in a triphase system with optical yields of up to 96percent is described.The influence of the molecular structure of the catalysts and substrates, the solvent, and the temperature on the stereochemistry is discussed.
Involvement of Zwitterionic Perepoxide Intermediate in Photooxygenation of α,β-Unsaturated Aromatic Ketones
Chawla, H. M.,Chakrabarty, Kakoli,Prakash, Anil,Chibber, S. S.
, p. 507 - 508 (2007/10/02)
Plausible involvement of a zwitterionic perepoxide intermediate in dye-sensitized photooxygenation of α,β-unsaturated aromatic ketones has been suggested.The carbonyl group in such compounds appears to have only a steric influence.
