Stereoselective Synthesis of alpha(2,9) Di- to Tetrasialic Acids, Using a 5,4-N,O-Carbonyl Protected Thiosialoside.
An efficient stereoselective synthesis of alpha(2,9) tetra- to disialic acids 1-3, using the 5,4-N,O-carbonyl protected thiosialoside 4, is described. The cyclic protecting group was effective for alpha-sialylation without the need for acetonitrile as the solvent. The donor 4 enabled the formation of a tetramer in excellent yield and selectivity. Deprotection of the cyclic protecting groups of the protected di- to tetrasialica acids proceeded smoothly to give the fully deprotected alpha(2,9) tetra- to disialic acids 1-3.
Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8552, Japan.
Hiroshi
H
Tanaka
Yuji
Y
Nishiura
Takashi
T
Takahashi
D012794:Sialic Acids / Q000138:chemical synthesis*; D013237:Stereoisomerism; D054330:Thiosugars / Q000737:chemistry
D012794:Sialic Acids; D054330:Thiosugars