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The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines.

McGrath MJ, Bolm C - Beilstein J Org Chem (2007)

Bottom Line: Chiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral, enantioenriched dialkyl sulfoximines with potential for use in asymmetric catalysis.Furthermore, a modified Horner-Emmons methodology was investigated.Simple chiral lithium amides afford products with enantiomeric excesses of up to 70%, illustrating that chiral base desymmetrisation of dimethyl sulfoximines is possible.

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Affiliation: Institut für Organische Chemie, Landoltweg 1, RWTH Aachen, Aachen 52074, Germany. matthew.mcgrath@oc.rwth-aachen.de

ABSTRACT

Background: Chiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral, enantioenriched dialkyl sulfoximines with potential for use in asymmetric catalysis.

Results: Asymmetric deprotonation of N-trialkylsilyl dimethyl sulfoximines with either enantiomer of lithium N,N-bis(1-phenylethyl)amide in the presence of lithium chloride affords enantioenriched sulfoximines on electrophilic trapping. Ketones, ketimines, trialkylsilyl chlorides and activated alkyl halides may be used as electrophiles in the reaction. Furthermore, a modified Horner-Emmons methodology was investigated.

Conclusion: Simple chiral lithium amides afford products with enantiomeric excesses of up to 70%, illustrating that chiral base desymmetrisation of dimethyl sulfoximines is possible.

No MeSH data available.


The influence of (S,S)-bis(1-phenylethyl)amine on the ee of 1b
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C5: The influence of (S,S)-bis(1-phenylethyl)amine on the ee of 1b

Mentions: A mechanism involving irreversible asymmetric deprotonation to a lithiated sulfoximine followed by rapid anion quenching on addition of the electrophile appears likely. An alternative equilibration of the sulfoximine anion with the chiral amine is less probable as racemic 2b was obtained in 23% yield after TMSCl quenching when sulfoximine 1b was first lithiated by treatment with n-BuLi followed by addition of a solution of (S,S)-bis-N,N-(1-phenylethyl)amine and lithium chloride (Scheme 5).


The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines.

McGrath MJ, Bolm C - Beilstein J Org Chem (2007)

The influence of (S,S)-bis(1-phenylethyl)amine on the ee of 1b
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2100055&req=5

C5: The influence of (S,S)-bis(1-phenylethyl)amine on the ee of 1b
Mentions: A mechanism involving irreversible asymmetric deprotonation to a lithiated sulfoximine followed by rapid anion quenching on addition of the electrophile appears likely. An alternative equilibration of the sulfoximine anion with the chiral amine is less probable as racemic 2b was obtained in 23% yield after TMSCl quenching when sulfoximine 1b was first lithiated by treatment with n-BuLi followed by addition of a solution of (S,S)-bis-N,N-(1-phenylethyl)amine and lithium chloride (Scheme 5).

Bottom Line: Chiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral, enantioenriched dialkyl sulfoximines with potential for use in asymmetric catalysis.Furthermore, a modified Horner-Emmons methodology was investigated.Simple chiral lithium amides afford products with enantiomeric excesses of up to 70%, illustrating that chiral base desymmetrisation of dimethyl sulfoximines is possible.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Organische Chemie, Landoltweg 1, RWTH Aachen, Aachen 52074, Germany. matthew.mcgrath@oc.rwth-aachen.de

ABSTRACT

Background: Chiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral, enantioenriched dialkyl sulfoximines with potential for use in asymmetric catalysis.

Results: Asymmetric deprotonation of N-trialkylsilyl dimethyl sulfoximines with either enantiomer of lithium N,N-bis(1-phenylethyl)amide in the presence of lithium chloride affords enantioenriched sulfoximines on electrophilic trapping. Ketones, ketimines, trialkylsilyl chlorides and activated alkyl halides may be used as electrophiles in the reaction. Furthermore, a modified Horner-Emmons methodology was investigated.

Conclusion: Simple chiral lithium amides afford products with enantiomeric excesses of up to 70%, illustrating that chiral base desymmetrisation of dimethyl sulfoximines is possible.

No MeSH data available.