Synthesis of substituted cyclodextrins

Cyclodextrins are naturally occurring, non-toxic and biodegradable cyclic oligosaccharides. The main feature of cyclodextrins is the ability to encapsulate lipophilic compounds, which has led to many applications. Although many cyclodextrin derivatives have become available on the market, their price is in the range of fine chemicals, and thus, they are still often synthesised in laboratories. The actual number of cyclodextrin derivatives exceeds 11,000, but new cyclodextrin derivatives are still needed for more advanced applications. Therefore, many beginners in cyclodextrin chemistry struggle with a reliable choice of a synthetic route. This review focuses on cyclodextrin derivatives that can be subsequently modified. Indeed, the modification of an already substituted cyclodextrin with a suitable functional group is much easier than the optimisation of the substitution for every new cyclodextrin derivative desired. This review describes the synthesis of different types of cyclodextrin derivatives: persubstituted, randomly substituted, persubstituted at selected positions, selectively substituted and monosubstituted cyclodextrins.