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

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.