Chemical synthesis using enzymatically generated building units for construction of the human milk pentasaccharides sialyllacto-N-tetraose and sialyllacto-N-neotetraose epimer

• Dirk Schmidt and
• Joachim Thiem

Beilstein J. Org. Chem. 2010, 6, No. 18, doi:10.3762/bjoc.6.18

• derivatives. Keywords: block synthesis; human milk oligosaccharides; sialyllacto-N-neotetraose epimer; sialyllacto-N-tetraose; trisaccharide thioglycoside donors; Introduction From an inspection of contemporary syntheses of biologically and medicinally relevant oligosaccharides, it is evident that the

• , sialyllacto-N-tetraose (1) and an epimer of sialyllacto-N-neotetraose (2) (Figure 1) were selected as target molecules. Both these pentasaccharides, Neu5Acα2-3Galβ1-3GlcNAcβ1-3Galβ1-4Glc (1) and Neu5Acα2-6Galβ1-4GlcNAcβ1-4Galβ1-4Glc (2), are dominant constituents of complex human milk oligosaccharides (Figure

• accessible selectively unprotected lactose acceptor glycosides the pentasaccharide structures sialyllacto-N-tetraose and the epimer of sialyllacto-N-neotetraose could be obtained in good yields, and subsequently transformed into their peracetylated derivatives for structure elucidation. Thus, a combination