Sulfonium ylide epoxidation reactions: methylene transfer

Bellenie, Benjamin R.; Goodman, Jonathan M.

doi:10.1039/b316653h

Cited by 28 publications

(9 citation statements)

References 12 publications

(15 reference statements)

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“…1 Initial studies were directed toward the synthesis of α,α′-bis-silanes such as 1 , R = Me 3 Si, Ph 3 Si, and t -BuMe 2 Si, from the readily available starting material 3 (Figure 1). 2 It seemed reasonable that rapid access to the series of silyl ligands 1 might be secured simply by sequential, one-flask silylation of monoanions derived from 3 or by one-step bis-silylation of the α,α′-dianion of 3 , a 12-π-electron (non-Hückel stabilized) system.…”

mentioning

confidence: 99%

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects

Han

Keresztes

et al. 2014

Org. Lett.

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confidence: 99%

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects

Han

Keresztes

et al. 2014

Org. Lett.

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“…Unfortunately, the highest enantioselectivity so far obtained for the synthesis of styrene oxide by this route is only 57 % ee with Goodman's sulfide 30 [21]. Thus methylidene transfer is not yet an effective strategy for the synthesis of terminal epoxides.…”

Section: Terminal Epoxidesmentioning

confidence: 99%

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

Aggarwal¹,

Badine²,

Moorthie³

2006

Aziridines and Epoxides in Organic Synthesis

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Epoxides and aziridines are strained three-membered heterocycles. Their synthetic utility lies in the fact that they can be ring-opened with a broad range of nucleophiles with high or often complete stereoselectivity and regioselectivity and that 1,2-difunctional ring-opened products represent common motifs in many organic molecules of interest. As a result of their importance in synthesis, the preparation of epoxides and aziridines has been of considerable interest and many methods have been developed to date. Most use alkenes as precursors, these subsequently being oxidized. An alternative and complementary approach utilizes aldehydes and imines. Advantages with this approach are: i) that potentially hazardous oxidizing agents are not required, and ii) that both C-X and C-C bonds are formed, rather than just C-X bonds (Scheme 1.1).This review summarizes the best asymmetric methods for preparing epoxides and aziridines from aldehydes (or ketones) and imines. Asymmetric Epoxidation of Carbonyl CompoundsThere have been two general approaches to the direct asymmetric epoxidation of carbonyl-containing compounds (Scheme 1.2): ylide-mediated epoxidation for the construction of aryl and vinyl epoxides, and a-halo enolate epoxidation (Darzens reaction) for the construction of epoxy esters, acids, amides, and sulfones.

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“…12 Using a D-mannitol derived chiral non-racemic sulfide, levels of enantiocontrol reached 57% in the formation of styrene oxide starting from benzaldehyde (54% yield). This is the highest level of enantiocontrol achieved to date when discussing methylene epoxidations.…”

Section: Introductionmentioning

confidence: 99%

S-Methylidene agents: preparation of chiral non-racemic heterocycles

et al. 2009

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Reaction of sulfur ylide with aldehyde, imine, and ketone functionality affords the desired three-membered heterocycle in excellent yield. The sulfur ylide is generated in situ upon decarboxylation of carboxymethylsulfonium betaine functionality. Of the seven carboxymethylsulfonium betaine derivatives surveyed, the highest level of conversion of π-acceptor to heterocycle was obtained having S-methyl and S-phenyl functionality bound to a thioacetate derivative. Methylene aziridinations and epoxidations involving the decarboxylation of carboxymethylsulfonium betaine functionality complements existing technologies with the advantages of the reaction protocol, levels of conversion and scope. While moderate levels of diastereocontrol were observed in the aziridination of imine functionality, the four oxiranes resolved using Jacobsen’s Co(II)-salen complex were obtained in both high yield and enantioselectivity. The isolated chiral non-racemic oxiranes constitute the formal synthesis of chelonin-B and combretastatin starting from 3-bromo-4-methoxybenzaldehyde and 3,4,5-trimethoxybenzaldehyde respectively.

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Sulfonium ylide epoxidation reactions: methylene transfer

Abstract: Using a D-mannitol derived chiral sulfide, terminal epoxides are formed in up to 76% ee; the first example of double asymmetric induction in a sulfonium methylide epoxidation is reported and an improved method of generating sulfonium ylides is detailed.

Cited by 28 publications

References 12 publications

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

S-Methylidene agents: preparation of chiral non-racemic heterocycles

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Sulfonium ylide epoxidation reactions: methylene transfer

Abstract: Using a D-mannitol derived chiral sulfide, terminal epoxides are formed in up to 76% ee; the first example of double asymmetric induction in a sulfonium methylide epoxidation is reported and an improved method of generating sulfonium ylides is detailed.

Cited by 28 publications

References 12 publications

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R3Si over Steric Shielding Effects

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R3Si over Steric Shielding Effects

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

S-Methylidene agents: preparation of chiral non-racemic heterocycles

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Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects

Preferential Geminal Bis-silylation of 3,4-Benzothiophane Is Caused by the Dominance of Electron Withdrawal by R₃Si over Steric Shielding Effects