Table 1: Sialylation with neuraminic acid derivatives.


#Sug-ClROHROH/
Sug-Cl
Ag2CO3/
Sug-Cl
AgOTf/
Sug-Cl
Time,
days
Sug-OR
(α)

+β, %

α, %
α/β b

1Neu5Ac (3)HO(CH2)3NHCOCF3522.6 (62 h)  47171  : 2 [8]
HO(CH2)3NHCOCF3230.10.2 (5 h)473695 : 5

3Neu5Gc (7)HO(CH2)3NHCOCF33338685792 : 8
44′,6′-diol-LacNAcβ-
O(CH2)3NHCOCF3
130.1710301243 : 57

59-deoxy-9-NAc-
Neu5Ac (14)
HO(CH2)3NHCOCF313315n.d.29Traces of β
64′,6′-diol-LacNAcβ-
O(CH2)3NHCOCF3
16517n.d.25Traces of β

7Neu5Ac2-8HO(CH2)3NHCOCF3237  2320not done94 : 6
8Neu5Ac 2-8HO(CH2)3NHCOCF3230.11363290 : 10
9(21+22)MeOH10060.15324n.d.40Traces of β
10HOCH2(p-C6H4)NHCOCH2NHBoc25 3  25201050 : 50
11HOCH2(p-C6H4)NHCOCH2NHBoc460.63321239 : 61

12Neu5Ac2-8
Neu5Ac2-8
Neu5Ac2-8 (31)
HO(CH2)3NHCOCF333 7  32332781 : 19
13HO(CH2)3NHCOCF3330.5737not done67 : 33

Preparative yield of unprotected glycoside Sug-OR calculated on protected precursor of Sug-Cl (n.d.: not determined);
/β ratio according to NMR data;
series of experiments demonstrated that these conditions are optimal for the reaction in the presence of AgOTf;
Recovery of the acceptor in the form LacNAcβ-O(CH2)3NH2 (11) 58%;
Recovery of the acceptor in the form LacNAcβ-O(CH2)3NH2 (11) 66%;
Reaction did not proceed without AgOTf.