Stereospecific synthesis of glycoside mimics through Migita-Kosugi-Stille cross-coupling reactions of chemically and configurationally stable 1-C-tributylstannyl iminosugars

International audienceAn innovative and effective strategy for the synthesis of imino-C-glycosides is described. The methodology is based on the unprecedent 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 (SR)-or (SS)-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 alpha-configured or beta-configured iminoglycosyl stannanes. With the subsequent stereoretentive CC bond-forming process, the methodology allows the synthesis of pseudo anomers of imino-C-glycosyl compounds in a controlled fashion