Cyclodextrin-Supported Passerini Three-Component Reaction as a Synthetic Platform for Homogeneous Modification of Carboxymethylcellulose in Aqueous Media

The prime objective of this study was to construct a synthetic platform for an aqueous reaction system that enabled chemical modification of environmentally friendly resources by using multicomponent reactions (MCRs). The target system was based on the Passerini three-component reaction (P-3CR) among carboxymethylcellulose (CMC), formaldehyde (F-CHO), and 1-adamantyl isocyanide (Adm-NC), which has been a heterogeneous reaction due to the insolubility of Adm-NC in water. Such a reaction to produce gel-like products is difficult to control. In this study, we added cyclodextrins (CDs) to the system to bypass uncontrolled interactions between the Adm-NC and water molecules by utilizing a host–guest complexation between the CDs and adamantane (Adm) derivatives. The CD-supported P-3CR homogeneously proceeded in water. The resulting products have been characterized to clarify the impact of the CDs and stoichiometric ratios of the three starting materials in the feeds. This paper includes another minor topic that CDs have been subsequently released by dialysis using an automatic continuous ultrafiltration apparatus, making the inherent Adm units exposed in aqueous media. The CD-released P-3CR products showed self-organization properties due to hydrophobic associations between the exposed Adm units.