Stereoselective Synthesis of γ,δ-Unsaturated β-Amino Sulfones from Ellman’s N-tert-Butylsulfinyl Ketimines and Methyl Phenyl Sulfone

A practical and straightforward approach for the highly stereoselective synthesis of γ,δ-unsaturated β-amino sulfones by nucleophilic (phenylsulfonyl)methylation of N - tert -butylsulfinyl ketimines with methyl phenyl sulfone was achieved. With lithium bis(trimethylsilyl)amide as the base, the corresponding sulfone-­stabilized carbanion derived from methyl phenyl sulfone can be transferred to ( S )-α,β-unsaturated N - tert -butylsulfinyl ketimines in very good yields and with high diastereoselectivities. Electron-withdrawing or electron-donating substituents on the aryl rings of ( S )-α,β-unsaturated N - tert -butylsulfinyl ketimines did not exert a significant effect on the outcome of the diastereoselective nucleophilic (phenylsulfonyl) methylation.