Synthesis of dendrimers via Staudinger/aza-Wittig reaction of Fréchet-type dendritic benzyl azides and Fréchet-type dendritic benzaldehydes

A synthetic strategy for dendrimers was developed using Staudinger/aza-Wittig reaction with an aldehyde and an azide in the presence of triphenylphosphine, followed by the reduction of imine intermediates. A fusion method between Frechet-type dendritic benzaldehydes and Frechet-type dendritic benzyl azides led to the formation of first-through fourth-generation dendrimers containing secondary amine as a connector in high yields. Further, fusion coupling using different generation dendrons afforded, efficiently, the unsymmetrical dendrimers. The obtained dendrimers were characterized by the analyses of 1H and 13C NMR spectroscopy, IR spectroscopy, mass spectra, and gel permeation chromatography (GPC) analysis.