Stereospecific Synthesis of Glycoside Mimics Through Migita‐Kosugi‐Stille Cross‐Coupling Reactions of Chemically and Configurationally Stable 1‐ C ‐Tributylstannyl Iminosugars

A process for the de novo synthesis of imino‐ C ‐glycosides is described. The methodology is based on the reaction of 1‐C‐stannylated iminosugars with various electrophiles under the conditions of Migita‐Kosugi‐Stille cross‐couplings, which gives 1‐C‐substituted iminosugar derivatives in a stereoretentive process. The required iminoglycosyl stannanes are obtained by way of the highly stereoselective addition of tributylstannyllithium to ( S R )‐ or ( S S )‐ N ‐ tert ‐butanesulfinyl glycosylamines, followed by an activation cyclization sequence. Most interestingly, the methodology is tunable: the configuration of the tin adduct is controlled exclusively by the tert ‐butanesulfinyl auxiliary, thus giving access after ring formation to ‘α’‐configured or ‘β’‐configured iminoglycosyl stannanes. With the subsequent stereoretentive C−C bond‐forming process, the methodology allows the synthesis of pseudo anomers of imino‐ C ‐glycosyl compounds in a controlled fashion.