Tri- and Tetrasaccharides

Scheme 11.19 One-pot syntheses of tri- and tetrasaccharides using relative reactivity data.

The carbohydrate part of various cardiac glycosides can be mono-, di-, tri-, and tetrasaccharide, and the aglycon (genin) is a steroid with certain unique structural characteristics. The main purpose of sugar residues is evidently to facilitate solubility of... 

Generally, carbohydrates are classified into four different categories, monosaccharides, di-, tri- and tetrasaccharides, oligosaccharides and polysaccharides. 

Di-, tri- and tetrasaccharides These carbohydrates are dimers, trimers and tetramers of monosaccharides, and are formed from two, three or four monosaccharide molecules, with the elimination of one, two or three molecules of water. For example, sucrose is a disaccharide composed of two monosaccharides, glucose and fructose. 

Knerr and Schmidt [145] have utilised RCM as a method for efficiently cleaving glycosides from PS. For example, treatment of resin-bound disaccharide 89 with 16 mol% of 2 in two batches gave allyl ether 90 in good yield. It was found that this method was convenient and generally applicable for the formation of di-, tri- and tetrasaccharides (Scheme 24) For other recent examples see Ref. [146]. For early examples of RCM cleavage see Ref. [147]. 

Fan and Hindsgaul have reported cyclic di-, tri-, and tetrasaccharides 187-189 <20020L4503>, in which the crucial macrocyclization was achieved through a base-promoted intramolecular Sn2 glycosylation in remarkably high yields (92-95%) and with a well-controlled stereochemistry. 

The substrate specificity of the fructosyltransferase from A. acukatus was estimated using a variety of di-, tri-, and tetrasaccharides at 100 g/1. The assay was... 

This soluble, cytosolic enzyme catalyses the 15 -0-acetylation of cardenolide tri- and tetrasaccharides. Using acetyl co-enzyme A as the acetyl donor, acetyl co-enzyme A digitoxin 15 -0-acetyltransferase (DAT) activity was detected... 

Benaissa-Trouw B, Lefeber DJ, Kamerling JP, Vliegenthart JF, Kraaijeveld K, Snippe H. Synthetic polysaccharide type 3-related di-, tri-, and tetrasaccharide-CRM(197) conjugates induce protection against Streptococcus pneumoniae type 3 in mice. Infect Immun. 2001 69 4698-4701. 

Dahmen, J, Gnosspelius, G, Larsson, A, Lave, T, Noori, G, Paalsson, K, Frejd, T, Magnusson, G, Synthesis of di-, and tri-, and tetrasaccharides corresponding to receptor structures recognized by Streptococcus pneumoniae, Carbohydr. Res., 138, 17-28, 1985. 

Zhu, Y, Kong, F, Regio- and stereoselective synthesis of 1—>6 linked manno-, gluco-, and galactopyranose di-, tri-, and tetrasaccharides via orthoester intermediates, J. Carbohydr. Chem., 19, 837-848, 2000. 

In the enzymatic production of XOS, low enzymatic activities are preferable in order to avoid degradation down to monosaccharides, di-, tri- and tetrasaccharides being the required products [305]. The enzyme used for XOS production is an endo-l-4-/3-xylanase (l,4-/3-D-xylan... 

Tri- and tetrasaccharides such as raffinose and stachyose may be separated with the chromatographic conditions given in Fig. 3-105. When adding sodium acetate to the... 

A series of five tri- and tetrasaccharides from Asparagus ocinalis L. 248... 

In 1998 Ogawa and coworkers revisited the synthesis of chondroitin sulfate and prepared the di-, tri-, and tetrasaccharides in their nonsulfated, 4-O-sulfated, 6-O-sulfated, and 4,6-di-O-sulfated forms (Fig. 5). As before, disaccharide III.39 was used as the primary building block for chain elongation. 

Scheme 20.5 Syntheses of tri- and tetrasaccharides (20 and 21) on soluble MPEG-support as precursors in the synthesis...

---