Unusual lactam formation occurring in the synthesis of a biotinylated T-antigen-serine derivative.

Abstract : Synthesis of the biotinylated T-antigens, linked to a serine by an alpha (7 alpha) or a beta (7 beta) 2-acetamido-2-deoxy-D-galactoside bond, is described. These derivatives were needed for the detection of a specific endogenous lectin at the surface and/or on the migration pathway of melanoma cells. In the course of the synthesis, an unusual lactam formation was observed with the beta anomer of the azido-disaccharide 5 beta.