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152 6 Chemo-Enzymatic Cascade Reactions for the Synthesis of Glycoconjugates

GlcNAcR
β4GalT1, β3GlcNAcT,
Sequential cascade NDP-sugars UDP-Glucose 4′-epimerase
synthesis
30 °C
Biocatalysis

OH OH OH O AcHN OH OH S
AcHN AcHN AcHN
O HO O HO R HO O HO N N NH 2
HO O O O O O HO O O O O H H
OH OH OH
OH OH OH OH
n = 3
Picoline borane complex
60 °C
n = 3
OH OH
AcHN N AcHN S
HO O HO
HO O O O O N NH
OH H
OH OH
OH OH OH NH
O HO AcHN O HO AcHN
S H O
N O HO O O O O R
R = N N OH OH
H H O OH OH
Figure 6.9 Convergent synthesis of complex branched poly-LacNAc structures. Two biocatalytic cascades consisting of a sequential and a one-
pot cascade are joined in a chemical reaction. Multiple parallel arrows indicate corresponding number of biocatalytic steps.