Remarkable ligand effect on the enantioselectivity of the chiral lanthanum complex-catalyzed asymmetric epoxidation of enones

Daikai, Kazuhiro; Kamaura, Masahiro; Inanaga, Junji

doi:10.1016/s0040-4039(98)01569-x

Cited by 111 publications

(40 citation statements)

References 6 publications

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“…The addition of 3-6 equivalents of Ph 3 P=O to the La-BINOL complex also enhances the rate of this reaction. 10 In fact, catalytic asymmetric epoxidation of 6f and 6j using the La-BINOLPh 3 P=O (1:1:3) complex 10 afforded similar results (entries 3, 9). In addition, we examined reactions using cumene hydroperoxide (CMHP) as an oxidant.…”

Section: Resultsmentioning

confidence: 83%

Unique reactivity of α,β‐unsaturated carboxylic acid imidazolides: Catalytic asymmetric synthesis of α,β‐epoxy esters and α,β‐epoxy carboxylic acid derivatives

et al. 2003

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Catalytic asymmetric synthesis of alpha,beta-epoxy esters and alpha,beta-epoxy carboxylic acid derivatives is described. Catalytic asymmetric epoxidation of alpha,beta-unsaturated carboxylic acid imidazolides using La-BINOL-Ph(3)As=O complex gave the corresponding alpha,beta-epoxy peroxy tert-butyl esters, which were directly converted to the alpha,beta-epoxy methyl esters by adding methanol to the reaction. This catalytic system had broad generality for epoxidation of various substrates. With the use of 5-10 mol% of the catalyst, both beta-aryl and beta-alkyl-substituted-alpha,beta-epoxy methyl esters were obtained in up to 91% yield and in up to 93% enantiomeric excess. In addition, efficient transformations of alpha,beta-epoxy peroxy tert-butyl esters into the alpha,beta-epoxy amides, alpha,beta-epoxy aldehydes, and gamma,delta-epoxy beta-keto esters are also reported.

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Section: Resultsmentioning

confidence: 83%

Unique reactivity of α,β‐unsaturated carboxylic acid imidazolides: Catalytic asymmetric synthesis of α,β‐epoxy esters and α,β‐epoxy carboxylic acid derivatives

et al. 2003

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“…Basically, their catalysts consist of a Lewis acidic lanthanoid atom, BINOL -derived chiral ligand, and triphenylarsine oxide. Inanaga and coworkers also reported that addition of triphenylphosphine oxide enhances the epoxidation catalysis of the lanthanoid complexes [64] . The Shibasaki ' s method has a broad substrate spectrum, and α , β -unsaturated ketones, esters, amides, and N -acyl pyrroles undergo epoxidation with high enantioselectivity.…”

Section: Lanthanoid Catalystmentioning

confidence: 97%

Asymmetric Oxidations and Related Reactions

Matsumoto

Katsuki

2010

Catalytic Asymmetric Synthesis

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GENERAL INTRODUCTIONOxidation is a fundamental technology for converting bulk chemicals into valuable materials and is also a useful tool for sophisticated functionalization of organic molecules. Thus, intensive research efforts have been devoted to the development of selective and practical oxidation methods, and a wide variety of chiral metal -based catalysts and organocatalysts have been developed for catalytic asymmetric oxidation reactions in industry and academia in the last half -century [1] . In contrast to the rapid improvement in stereoselectivity, the enhancement of atom economy [2] falls behind. While atom effi ciency (especially active oxygen content in oxygenation reactions) of stoichiometric oxidants is a factor that should be considered, most of the catalytic asymmetric oxidations still use conventional stoichiometric oxidants of low atomeffi ciency such as peracids, alkyl hydroperoxides, hypervalent iodine reagents, hypochlorite, and N -oxide compounds (Table 11.1 ). The use of such oxidants causes the formation of large amounts of undesirable waste. From the viewpoint of ecological sustainability, oxidation with a higher atom -effi cient, safe, abundant, and preferably inexpensive oxidant is favorable. Considering the requirements, molecular oxygen and hydrogen peroxide are the oxidants of choice [3] . Molecular oxygen offers a large advantage because it is abundant in air and is inexpensive. Aerobic oxidation that directly uses ambient air as an oxidant is similar to respiration in living organisms. Hydrogen peroxide is also recognized as a green oxidant. It is almost as equally atomeffi cient as molecular oxygen, and the by -product is safe and clean water. Moreover, its aqueous solution (typically 30 -35%) is inexpensive and easy to handle. Consequently, the development of catalytic asymmetric oxidations with molecular oxygen Catalytic Asymmetric Synthesis, Third Edition, Edited by Iwao Ojima

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“…Inanaga and coworkers improved the catalytic efficiency of this system by adding triphenylphosphine oxide in larger amounts with respect to the lanthanum metal, thus reducing the reaction time for the epoxidation [29]. Shibasaki showed that the addition of catalytic loadings of (Ph) 3 AsO would enable a further improvement in the efficiency of the epoxidizing system, reducing the reaction time from hours to minutes [30].…”

Section: Epoxidation Of αβ-Unsaturated Ketones Amides and Esters Mmentioning

confidence: 99%

Asymmetric Epoxidations of α,β‐Unsaturated Carbonyl Compounds

Lattanzi

2010

Catalytic Asymmetric Conjugate Reactions

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The asymmetric epoxidation of alkenes is a fundamental process in organic synthesis, and unquestionably the most exploited approach to synthesize epoxides [1]. Alternative useful strategies to access these molecules concern the enantioselective alkylidenation of carbonyl compounds by ylides [2] and the Darzens condensation [3]. Enantioenriched epoxides are important targets of biological and pharmaceutical interest. Moreover, their high synthetic potential as intermediates is exemplified by the stereoselective ring opening with nucleophiles, which affords a variety of compounds with two contiguous chiral centers, the absolute configuration of which can be controlled [4].During the past few decades, metal-based electrophilic asymmetric methodologies of epoxidation have been successfully developed and found widespread application in multistep synthesis; these include: the Sharpless' epoxidation of allylic alcohols mediated by the Ti/tartrate system [5]; and the Jacobsen's and Katsuki's epoxidation of unfunctionalized alkenes by using Mn-and Ti-/Salen complexes [6]. More recently, chiral Ru-Pt and Fe-Pt complexes have proved to be effective in the enantioselective epoxidation of disubstituted aromatic and challenging terminal unfunctionalized alkenes [7]. Impressive results have been achieved by the groups of Yang [8] and Shi [9] for the electrophilic organocatalyzed asymmetric epoxidation of a great variety of olefins such as trisubstituted, disubstituted trans-alkenes, terminal alkenes, dienes, and enynes (to cite the most relevant examples), and by the in situ generation of dioxiranes derived from chiral ketones. Within the context of asymmetric epoxidation catalyzed by organic promoters, notable achievements have also been attained by using chiral oxaziridines [10], oxaziridinium salts [11], amines [12], and peptide-based peracids [13].The epoxidation of α,β-unsaturated carbonyl compounds leads to the formation of another valuable class of functionalized epoxides [14], the carbonyl and epoxide groups of which can be selectively manipulated to provide enantioenriched products such as allylic epoxy alcohols, α-or β-hydroxy ketones, and α,β-epoxy esters [15]. The general approach for the epoxidation of electron-poor Catalytic Asymmetric Conjugate Reactions. Edited by Armando Córdova

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Remarkable ligand effect on the enantioselectivity of the chiral lanthanum complex-catalyzed asymmetric epoxidation of enones

Cited by 111 publications

References 6 publications

Unique reactivity of α,β‐unsaturated carboxylic acid imidazolides: Catalytic asymmetric synthesis of α,β‐epoxy esters and α,β‐epoxy carboxylic acid derivatives

Unique reactivity of α,β‐unsaturated carboxylic acid imidazolides: Catalytic asymmetric synthesis of α,β‐epoxy esters and α,β‐epoxy carboxylic acid derivatives

Asymmetric Oxidations and Related Reactions

Asymmetric Epoxidations of α,β‐Unsaturated Carbonyl Compounds

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