Developments in the Simmons−Smith-Mediated Epoxidation Reaction

Aggarwal, Varinder K.; Coogan, Michael P.; Stenson, Rachel A.; Jones, Ray V. H.; Fieldhouse, Robin; Blacker, John

doi:10.1002/1099-0690(20021)2002:2<319::aid-ejoc319>3.0.co;2-r

Cited by 45 publications

(24 citation statements)

References 12 publications

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“…Among the terminal aziridines, 1,2‐diaryl‐substituted derivatives 4 have received little attention despite the fact that some of them constitute an interesting class of pesticides with a very low oral mammalian toxicity. Their enantiopure forms have never been synthesized10 and early attempts at asymmetric synthesis have resulted in poor enantioselectivity 4a. Herein, we report on a new and practical synthesis of 1,2‐diaryl aziridines 4 by the enantioselective reductive amination of α‐chloroketones 1 .…”

Section: Methodsmentioning

confidence: 99%

Enantioselective Synthesis of 1,2‐Diarylaziridines by the Organocatalytic Reductive Amination of α‐Chloroketones

2007

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Section: Methodsmentioning

confidence: 99%

Enantioselective Synthesis of 1,2‐Diarylaziridines by the Organocatalytic Reductive Amination of α‐Chloroketones

2007

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“…Aggarwal and co-workers found that zinc carbenoids generated from Et 2 Zn and ClCH 2 I could efficiently transfer a methylidene group to a sulfide, and, in the presence of aldehydes, produce epoxides in good yield (Scheme 1.13) [19,20].…”

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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“…The same author has as well demonstrated a similar catalytic cycle using Simmons-Smith reagents (Et 2 Zn/ClCH 2 I) as S-ylide precursors to perform asymmetric methylene transfers (Scheme 3). 11…”

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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Developments in the Simmons−Smith-Mediated Epoxidation Reaction

Cited by 45 publications

References 12 publications

Enantioselective Synthesis of 1,2‐Diarylaziridines by the Organocatalytic Reductive Amination of α‐Chloroketones

Enantioselective Synthesis of 1,2‐Diarylaziridines by the Organocatalytic Reductive Amination of α‐Chloroketones

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines

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

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