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
Internally Protected Amino Sugar Equivalents from Enantiopure 1,2‐Oxazines: Synthesis of Variably Configured Carbohydrates with C‐Branched Amino Sugar Units
作者:Fabian Pfrengle、Hans‐Ulrich Reissig
DOI:10.1002/chem.201001060
日期:2010.10.18
precursors allowed the synthesis of homo‐oligomeric di‐ and trisaccharides 44, 46 and 47 or a hybrid trisaccharide 51 with natural carbohydrates. Access to a bivalent amino sugar derivative 54 was accomplished by reaction of rearrangement product 10 with 1,5‐pentanediol. Alternatively, when a protected L‐serine derivative was employed as glycosyl acceptor, the glycosylated amino acid 60 was efficiently prepared