177314-49-7Relevant academic research and scientific papers
Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by rare-earth metal amides RE[N(SiMe3)2]3with chiral TADDOL ligands
Shan, Haiwen,Lu, Chengrong,Zhao, Bei,Yao, Yingming
, p. 1043 - 1053 (2021/01/25)
The catalytic asymmetric epoxidation of α,β-unsaturated ketones by tert-butylhydroperoxide (TBHP) has been well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Y(4), Yb(5)) with chiral TADDOL ligands. It was found that
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.
Enantioselective epoxidation of α,β-unsaturated ketones catalyzed by stapled helical l-Leu-based peptides
Demizu, Yosuke,Yamagata, Nanako,Nagoya, Saori,Sato, Yukiko,Doi, Mitsunobu,Tanaka, Masakazu,Nagasawa, Kazuo,Okuda, Haruhiro,Kurihara, Masaaki
experimental part, p. 6155 - 6165 (2011/09/19)
Stapled helical l-leucine-based heptapeptides were synthesized and used as catalysts for the enantioselective epoxidation of α,β-unsaturated ketones. All N-terminal free stapled peptides were successfully used as chiral catalysts. Among them, the use of H-hS3,7hS-10 gave epoxide products with high enantioselectivities of up to 99% ee. Furthermore, the dominant conformations of the N-terminal protected stapled peptides R 3,7R-10 and hS3,7hS-10 were investigated by 1H NMR, IR, CD spectra, and X-ray crystallographic analysis. The peptide R3,7R-10 formed a right-handed (P) α-helix in solution and in the crystalline state, while hS 3,7hS-10 formed a right-handed (P) 310-helix in solution.
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.
Diastereo- and enantioselective synthesis of α,β-epoxyketones using aqueous NaOCl in conjunction with dihydrocinchonidine derived phase-transfer catalysis at room temperature. Scope and limitations
Lygo, Barry,Gardiner, Stuart D.,McLeod, Michael C.,To, Daniel C.M.
, p. 2283 - 2290 (2008/03/12)
In this paper we present studies into the scope and limitations of asymmetric PTC epoxidation of enones and the oxidation-epoxidation of allylic alcohols using aqueous NaOCl in conjunction with a dihydrocinchonidine derived quaternary ammonium salt cataly
Design of new chiral phase-transfer catalysts with dual functions for highly enantioselective epoxidation of α,β-unsaturated ketones
Ooi, Takashi,Ohara, Daisuke,Tamura, Masazumi,Maruoka, Keiji
, p. 6844 - 6845 (2007/10/03)
A new chiral ammonium bromide, 1-Br, possessing diarylmethanol functionality as a substrate recognition site has been designed as a promising, dual-functioning catalyst for the highly enantioselective epoxidation of α,β-unsaturated ketones under mild phas
Remarkable effect of tris(4-fluorophenyl)phosphine oxide on the stabilization of chiral lanthanum complex catalysts. A new and practical protocol for the highly enantioselective epoxidation of conjugated enones
Kino, Rie,Daikai, Kazuhiro,Kawanami, Toshio,Fumno, Hiroshi,Inanaga, Junji
, p. 1822 - 1824 (2007/10/03)
A new and efficient chiral catalyst system, lanthanumchiral BINOL-tris(4-fluorophenyl)phosphine oxidecumene hydroperoxide, was developed for the epoxidation of α,β-unsaturated ketones thus providing the corresponding epoxy ketones with excellent enantiose
Chiral ligand-controlled catalytic asymmetric epoxidation of α,β-unsaturated carbonyl compounds with peroxide
Tanaka, Yoshihito,Nishimura, Katsumi,Tomioka, Kiyoshi
, p. 4549 - 4556 (2007/10/03)
Asymmetric epoxidation reaction of α,β-unsaturated carbonyl compounds with alkylperoxide was catalyzed by an external chiral tridentate aminodiether-lithium peroxide giving epoxides with good enantiomeric excess. Slow addition of alkylhydroperoxide was beneficial for a catalytic asymmetric reaction. Lone pair electron-differentiating coordination of a carbonyl oxygen to lithium is another critical factor for high enantioselectivity.
Chiral ligand-controlled catalytic asymmetric epoxidation of enone with hydroperoxide
Tanaka, Yoshihito,Nishimura, Katsumi,Tomioka, Kiyoshi
, p. 71 - 73 (2007/10/03)
Conjugate addition-type asymmetric epoxidation of an enone with lithium cumene hydroperoxide was mediated by a chiral ligand. The catalytic process was realized under conditions of a slow addition of cumene hydroperoxide.
beta-peptides as catalysts: poly-beta-leucine as a catalyst for the Julia-Colonna asymmetric epoxidation of enones.
Coffey,Drauz,Roberts,Skidmore,Smith
, p. 2330 - 2331 (2007/10/03)
Poly-beta-leucines have been evaluated as catalysts for the Julia-Colonna asymmetric epoxidation of enones; the beta 3-isomer was found to be an effective catalyst for the epoxidation of chalcone (70% ee) and some analogues.
