102490-11-9Relevant articles and documents
Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex: Structural determination of the asymmetric catalyst
Nemoto,Ohshima,Yamaguchi,Shibasaki
, p. 2725 - 2732 (2001)
The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph3As=O complex generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)2(Ph3As=O)2 (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph3As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)3 for accelerating the epoxidations while maintaining high ee's is discussed.
Catalytic asymmetric epoxidation of α,β-unsaturated ketones promoted by lanthanoid complexes
Bougauchi,Watanabe,Arai,Sasai,Shibasaki
, p. 2329 - 2330 (1997)
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Asymmetric Epoxidation of Enones Promoted by Dinuclear Magnesium Catalyst
Jaszczewska-Adamczak, Joanna A.,Mlynarski, Jacek
supporting information, p. 4247 - 4255 (2021/07/17)
Asymmetric synthesis with cheaper and non-toxic alkaline earth metal catalysts is becoming an important and sustainable alternative to conventional catalytic methodologies mostly relying on precious metals. In spite of some sustainable methods for enantioselective epoxidation of enones, the development of a well-defined and efficient catalyst based on magnesium complexes for these reactions is still a challenging task. In this perspective, we present the application of chiral dinuclear magnesium complexes for asymmetric epoxidation of a broad range of electron-deficient enones. We demonstrate that the in situ generated magnesium-ProPhenol complex affords enantioenriched oxiranes in high yields and with excellent enantioselectivities (up to 99% ee). Our extensive study verifies the literature data in this area and provides a step forward to better understand the factors controlling the oxygenation process. Elaborated catalyst offers mild reaction conditions and a truly wide substrate scope. (Figure presented.).
Facial selectivity and stereospecificity in the (4 + 3) cycloaddition of epoxy enol silanes
Lo, Brian,Chiu, Pauline
supporting information; experimental part, p. 864 - 867 (2011/05/06)
The scope of the (4 + 3) cycloaddition using epoxy enol silanes has been examined. Unhindered and nucleophilic dienes react to give the highest yields, but hindered dienes give rise to higher diastereoselectivities. Notably, the cycloaddition shows facial
Asymmetric oxidations of electron-poor alkenes promoted by the β-amino alcohol/TBHP system
Russo, Alessio,Lattanzi, Alessandra
experimental part, p. 1551 - 1556 (2009/12/06)
The asymmetric oxyfunctionalization of alkenes is a fundamental process in synthetic organic chemistry. In this contribution, we review our findings on the enantioselective organocatalyzed oxidation of electron-poor alkenes. Readily or commercially available β-amino alcohols displayed catalytic activity in the asymmetric epoxidation of α,β-enones and β-peroxidation of nitroalkenes with tert-butyl hydroperoxide (TBHP) as the oxidant. The corresponding epoxides and peroxides were isolated in good to high yield and enantioselectivity. Georg Thieme Verlag Stuttgart.
