Organocatalysis of asymmetric epoxidation by iminium salts using sodium hypochlorite as the stoichiometric oxidant

Page, Philip C. Bulman; Parker, Phillip; Buckley, Benjamin R.; Rassias, Gerasimos A.; Bethell, Donald

doi:10.1016/j.tet.2009.02.007

Cited by 30 publications

(14 citation statements)

References 84 publications

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“…[32] Along the lines of oxaziridines, Bulman Page and co-workers have spent most of their research in the epoxidation of alkenes by using iminium salts such as 13 and 14 ( Figure 1). [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] More recently,i n2 013, Bulman Page managed to extend the use of catalyst 15 in heterogeneousc atalysis, while showing the first resultso fk inetic resolution in the epoxidation reaction by employing iminium salt catalysis,b yw hich enantiomeric excess values of up to 99 %f or the epoxidation of racemic cischromenes could be achieved (Scheme 11). Furthermore, a new familyo fc arbohydrate-based dihydroisoquinolinium salts 14 and 16 has been reported,a nd most recently,B ulman Page and co-workersh ave developed the first examples of the asymmetrice poxidation of dihydroquinoline substrates with iminium salt catalysts (Scheme 12).…”

Section: Historic Backgroundont He Organocatalytic Epoxidationmentioning

confidence: 99%

Green Organocatalytic Oxidative Methods using Activated Ketones

2018

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Alkenes are very important moieties in organic chemistry and have been employed as starting materials for the synthesis of important organic compounds. In this review, we present organocatalytic reactions in which alkenes play a central role, especially their organocatalytic oxidation to epoxides. This topic plays a pivotal role in our recent research, for which we utilize H2O2 as a green oxidant and a ketone as the catalyst. Extension to other oxidative transformations is also presented.

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Section: Historic Backgroundont He Organocatalytic Epoxidationmentioning

confidence: 99%

Green Organocatalytic Oxidative Methods using Activated Ketones

2018

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“…Ph Eur, Merck). Tetrahydronaphthalene-1,2-epoxide [22] and β-methylstyrene oxide [28] were synthesized according to literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Regioselectivity Control of the Ring Opening of Epoxides With Sodium Azide in a Microreactor

et al. 2012

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The reaction of different types of aromatic and aliphatic epoxides with sodium azide to give vicinal azido alcohols was studied in a microreactor with and without pillars in the channels. Dependent on the substrate, the regioselectivity of the ring opening is affected by the used solvent system, viz. acetonitrile-water (sometimes with 10% acetic acid to promote the reactivity of substrates) or t-butyl acetate-water containing Tween80 as a surfactant. For styrene oxide and α-methylstyrene oxide, the α/β regioselectivity changes from 4 to 10 and 1.7 to 6.2, respectively, going from acetonitrile-water to Tween80-containing t-butyl acetate-water. The addition of a surfactant (Tween80) stabilizes the interface in the biphasic t-butyl acetate-water. Pillar-containing microreactors gave better conversions than microreactors without pillars and lab scale reactions, probably due to better mixing.

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“…A radical mechanism suggests that the trans-epoxide can be formed by a single electron transfer mechanism, due to C-C bond rotation around the intermediate species (Scheme 11). 26 Chapter 1 -Introduction…”

Section: Jacobsen-katsuki Epoxidationmentioning

confidence: 99%

“…Page has shown that a range of oxidants can be implemented in the catalytic iminium-salt mediated asymmetric epoxidation of olefins, including Oxone™, 25 sodium hypochlorite, 26 hydrogen peroxide, 27 and, most recently, tetraphenylphosphonium monoperoxysulfate (TPPP) under non-aqueous conditions. 16,17,18,28 Di Furia first reported the synthesis of TPPP in 1994.…”

Section: Synthesis Of Tetraphenylphosphonium Monoperoxysulfate (Tppp) 71mentioning

confidence: 99%

Recent Advances in Iminium‐Salt‐Catalysed Asymmetric Epoxidation

Day

Sellars

2016

Eur J Org Chem

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The research in this thesis depicts some of the most current developments in the area of asymmetric epoxidation of alkenes using chiral iminium salt catalysts. The first chapter reviews past and present developments in; catalytic asymmetric epoxidation, and covers the application of this reaction towards the kinetic resolution of racemic olefins.Chapter two is separated into two key areas; (i) asymmetric epoxidation as a tool in the kinetic resolution of racemic chromene substrates, and (ii) investigations into the asymmetric epoxidation of new N-protected dihydroquinoline substrates. In the first part of chapter two, the first examples of kinetic resolution in epoxidation reactions using iminium salt catalysts are reported, providing up to 98% ee in the epoxidation of racemic cis-chromenes.The second part of chapter two details the first known examples of asymmetric epoxidation upon nitrogen-protected dihydroquinoline substrates, affording enantioselectivities as high as 73% ee.In both parts of chapter two, non-aqueous epoxidation conditions were employed using Page's dihydroisoquinolinium iminium salt catalyst. The later part of chapter two introduces a biphenylazepinium iminium salt catalyst used under aqueous epoxidation conditions. Chapter three includes experimental data for all the compounds mentioned in chapter two, with chapter four containing HPLC traces to show determination of enantiomeric excess of epoxides, and enantioenriched alkene traces.iii ACKNOWLEDGEMENTS

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Organocatalysis of asymmetric epoxidation by iminium salts using sodium hypochlorite as the stoichiometric oxidant

Cited by 30 publications

References 84 publications

Green Organocatalytic Oxidative Methods using Activated Ketones

Green Organocatalytic Oxidative Methods using Activated Ketones

Regioselectivity Control of the Ring Opening of Epoxides With Sodium Azide in a Microreactor

Recent Advances in Iminium‐Salt‐Catalysed Asymmetric Epoxidation

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