Chapter 2. Cucurbituril Homologues and Derivatives: Syntheses and Functionalization

In this chapter, we discuss the syntheses and functionalization of cucurbituril (CB[n]) homologues and derivatives. We begin with a historical background on CB[n] chemistry, from the first known CB[n] homologue, CB[6], to the latest advances in functionalized CB[n] synthesis. Then we elaborate on unsubstituted CB[n] homologues regarding their synthesis, isolation, formation mechanisms, and structural and physical properties. We broadly discuss the synthesis of substituted CB[n] derivatives with various strategies. There are three known methods to synthesize substituted CB[n] from modified precursors: (1) use of substituted glycoluril, (2) use of substituted glycoluril oligomers and (3) use of aldehydes other than formaldehyde. In the last part of the chapter, we give detailed information on the direct functionalization of CB[n]. This part presents the synthesis of multi- and monohydroxylated derivatives via radical oxidation of CB[n] homologues and their further derivatization to reactive groups bearing multi- and monoalkylated CB[n].