Catalyst-Free Syntheses of [2]Rotaxanes Utilizing a Pentacoordinated Hydrosilane as an End-Capping Agent
摘要:
A pentacoordinated hydrosilane activated by an intramolecular nitrogen silicon dative bond was utilized as an end-capping agent for catalyst-free syntheses of [2]rotaxanes. The end-capping reaction of a pseudo[2]rotaxane bearing a salicylic acid terminus with the pentacoordinated hydrosilane readily proceeded at room temperature to produce the corresponding silyl-capped [2]rotaxane.
Reactions of a neutral pentacoordinated monohydrosilane bearing a dative N-Si bond with phenol and benzoic acid derivatives gave the corresponding pentacoordinated phenoxysilane and carboxysilanes, respectively. X-ray crystallographic analyses of these silanes revealed that the distance of the N-Si dative bond is shortened and the pentacoordination character of the silicon center becomes greater with the increase in the electron-withdrawing character of the apical substituent on silicon.