Convenient assembly of trimeric Lex determinants using carbosilane scaffolds by means of Huisgen cycloaddition

The LeX glycoside having an N3 moiety at the ω position, which was prepared by using living cells from GlcNAcO(CH2)12N3 as a starting material, was efficiently introduced into a trivalent-type carbosilane core scaffold by means of Huisgen cycloaddition reaction to yield the corresponding glycocluster having three LeX moieties at each end. Structural elucidation of the product was performed by a combination of NMR and mass spectroscopic analyses, and the results of the analyses supported the structure of the glycocluster. Evaluation of the glycocluster was carried out using Lotus lectin as a model lectin. Environmental changes of tryptophan residues located at or near the binding sites of Lotus lectin caused fluorescence intensity change.