α,N-Alkanesulfonamide Dianions: Formation and Chemoselective C-Alkylation

Article abstract of DOI:10.1021/jo00184a006

Mono-N-substituted alkanesulfonamides such as 11 (Scheme I) can be treated with 2 equiv of a strong base (n-butyllithium or LDA) to generate the hitherto unreported dianionic species 12.Addition of electrophiles (alkylhalides, aldehydes, ketones, nitriles) to THF solutions of these dianions results in clean, chemoselective reaction on the carbon atom.Removal of the "protecting" group from nitrogen releases a primary sulfonamide, which may then be selectively functionalized.This method permits the preparation of a wide variety of substituted sulfonamides that might otherwise prove difficult to synthesize.As demonstration of the further utility of these adducts, β-hydroxy sulfonamides such as 14 were converted to either β-styrenesulfonamides 15 (and 16) or 1,2-thiazetidine 1,1-dioxides (18) (Scheme II).