摘要:
We describe the efficient synthesis of the tetrasaccharide, 2-O-acetyl-3,4,6-tri-O-benzyl-alpha-D-mannopyranosyl-(1 -> 6)-2,4-di-O-acetyl-3-O-allyl-p-D-mannopyranosyl-(1 -> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-O-D-glucopyranosyl-(1 -> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl azide, which is the protected form of the sugar unit of TIME-EA4 that is isolated from the diapausing eggs of the silkworm, Bombyx mori. The P-linked D-mannoside of the tetrasaccharide was obtained using the conventional oxidation-reduction method for inversion of the configuration at the C-2 hydroxyl group Of P-D-glucoside. The reduction was effected with NaBH4 in a methanolic solution in a ratio of 98:2 in favor of the P-D-mannoside that was obtained in 87% yield. (c) 2006 Elsevier Ltd. All rights reserved.