Cyclodextrins (CDs), cyclic oligosaccharides, are water-soluble host molecules that can include various kinds of guest molecules utilized not only in basic research but also as food additives. CDs with oligo-glucose structure have interesting properties; however, CDs can be chemically modified and thereby acquire new functions. We are studying the artificial hemoglobin “hemoCD”, which consists of a per-O-methylated CD dimer and iron porphyrin (FeTPPS). In this article, I describe the strategy of hemoCD preparation and its medical applications. ...and more
Cyclodextrins (CDs) are cyclic oligomers of α-1,4-D-glucopyranoside. Because the central cavities of CDs can be used to encapsulate small molecules, cyclic hexamer to octamer (CD6–8) have been widely used. While CD-hundreds are known for large CDs, the synthesis of the only CD5 had been only one reported for small CDs. Smaller CDs, such as CD4 and CD3, have never been synthesized because their molecular sizes are too small for the pyranose ring to adopt a stable chair-type conformation. In this report, we describe the chemical synthesis of both CD4 and CD3. The development of a specific bridging group between the 3- and 6-oxygen positions (O-3 and O-6) of D-glucose led to the successful synthesis of these compounds. In other words, the adoption of this bridging group provides both the stereoselective glycosylation reaction and the supple conformation of the pyranose ring, which are required for the synthesis of CD4 and CD3. ...and more
