The effect of the primary structure of the polypeptide catalyst on the enantioselectivity of the Juliá–Colonna asymmetric epoxidation of enones

Bentley, P. H.; Flood, Robert W.; Roberts, Stanley M.; Skidmore, John; Smith, Corina B.; Smith, J. A. S.

doi:10.1039/b104123c

Cited by 43 publications

(15 citation statements)

References 7 publications

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“…Later, when Roberts investigated the role of the amino acid at the N-terminus of the catalyst [66], it was shown that those residues close to the N-terminus of the chain determined the sterochemical outcome of the oxidation. If the amino acids in the oligomers were changed and tested in the epoxidation of trans-chalcone 1c, the penultimate and penultimate-plus-one residues were shown to play a crucial role.…”

Section: Polyamino Acidsmentioning

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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Section: Polyamino Acidsmentioning

confidence: 99%

Asymmetric Epoxidations of α,β‐Unsaturated Carbonyl Compounds

Lattanzi

2010

Catalytic Asymmetric Conjugate Reactions

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“…Immobilization of the poly(amino acid) on silica had been already described by Roberts and provided the optimum heterogeneous catalyst in terms of efficiency, stability and ease of recycling. 18 ð2Þ…”

Section: A Enantioselective C-o Bond Forming Catalystsmentioning

confidence: 99%

Recoverable and recyclable chiral organic catalysts

Benaglia

2006

New J. Chem.

121

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“…3,7 Although the diastereoselective epoxidation of electron-rich alkenes by these two oxidants is well documented, 8 the reaction of electron-poor substrates remains a synthetic challenge. 9 Urea-hydrogen peroxide (UHP) is both cheap and safe, yielding an innocuous byproduct in oxidation reactions. It has the advantages of being relatively stable and more convenient in use than aqueous hydrogen peroxide.…”

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confidence: 99%