Current Organic Chemistry Volume 5, Number 12, 2001
Contents
Carbohydrate Chemistry
Executive
Editor: Zbigniew J. Witczak
Synthesis of C-Saccharides and Higher Congeners Pp. 1133-1167
Lei Liu, Michael McKee and Maarten H. D. Postema
Large-scale Synthesis of Carbohydrates for Pharmaceutical Development Pp. 1169-1176
Jianbo Zhang, Bingyuan Wu, Ziye Liu, Premzek
Kowal, Xi Chen, Jun Shao and Peng
George Wang
Synthesis and Biological Properties of Monothiosaccharides Pp. 1177-1214
Inmaculada Robina, Pierre Vogel and Zbigniew J. Witczak
[Back to top] Synthesis of C-Saccharides and Higher Congeners
This work reviews the synthesis of a class of stable sugar mimics termed, C-saccharides. These compounds are stable analogs of the corresponding O-saccharides in which the interglycosidic oxygen has been replaced by a carbon atom. For the most part, this review focuses on the synthesis of C-disaccharides. The organization is based on the type of chemistry used to assemble the target and has the following sub-sections: sigmatropic approaches, synthesis based on the cationic reactivity of the anomeric carbon atom, metal-mediated processes, cyclization methodology, processes based on anionic chemistry and methods based on free radical chemistry.
[Back to top] Large-scale Synthesis of Carbohydrates for Pharmaceutical Development
The field of glycobiology has recently enjoyed an enormous expansion boosted by new discoveries of the critical functions that carbohydrates play in nature. Further research in this area and the entry of carbohydrates into the medical and pharmaceutical fields will undoubtedly require easy access to these molecules. Recombinant glycosidases and glycosyltransferases, as well as their mutants and fusion proteins have already been applied in gram or even larger scale carbohydrate synthesis. Most efficient synthetic systems require expensive sugar nucleotides to be regenerated in situ. Solid support-immobilized biosynthetic enzymes and genetically engineered microorganisms have been demonstrated as viable and highly effective avenues to make carbohydrates. The efficiency of such systems makes them ideal for industry and should, at long last, make production of complex carbohydrates economically feasible.
[Back to top] Synthesis and Biological Properties of Monothiosaccharides
Inmaculada Robina, Pierre Vogel and Zbigniew J. Witczak
As other monosaccharide mimics such as the azasugars and
the carbasugars (with nitrogen
and carbon atom, respectively, instead of oxygen
atom in the ring) the thiosugars (with sulfur atom instead of oxygen atom in
the ring) have gained importance in glycobiology and as potential drugs.
Biological properties of monothiosaccharides are presented and the methods for
their synthesis are reviewed and analyzed. Since the report of the synthesis of
5-thio-a-D-xylopyranose, the first
example of thiosugars ever described, forty years of imaginative chemistry have
produced a large number of monothiosaccharides and of analogs of biological
interest. The preparative chemists have at their disposal a panoply of mthodologies
relying on pure chemical or on biochemical means, using carbohydrate or
non-carbohydrate precursors. Because the sulfur moieties can participate more
readily than the corresponding oxygen moieties in heterolytical processes, the
chemistry of the thiosugars and their analogs is more subtile and sometimes
more delicate than that of the corresponding aldoses and alditols.