concealed: 1,2‐oxazines such as 1 rearrange under Lewisacidic conditions to bicyclic products of type 2, which can be incorporated into oligosaccharides as protected aminosugar equivalents. Subsequent reductive steps provide unusual oligosaccharides 3 having C2‐branched 4‐aminosugar units. Most of the reactions proceed with excellent stereocontrol and allow the synthesis of a collection of stereoisomers