Olive-Shaped Organic Cages: Synthesis and Remarkable Promotion of Hydrazone Condensation through Encapsulation in Water
Yanyan Xu, Hongkun Liu, Zekun Wang, Bo Song, Dan‐Wei Zhang, Hui Wang, Zhiming Li, Xiaopeng Li, Zhan‐Ting Li
Abstract
Two organic cages have been prepared in situ in water through the 2 + 3 hydrazone coupling of two pyridinium-derived trialdehydes and oxalohydrazide. The highly water-soluble cages encapsulate and solubilize linear neutral molecules. Such encapsulation has been applied for the promotion of both two- or three-component hydrazone condensation in water. For two-component reactions, the yields of the resulting monohydrazones are increased from 5-10 to 90-96%. For three-component reactions of hydrazinecarbohydrazide with 11 aromatic aldehydes, in the presence of the organic cages, the bihydrazone products can be produced in 88-96% yields. In contrast, without the promotion of the organic cages, 9 of the reactions do not afford the corresponding dihydrazone product.