Synthesis of Fréchet-type Dendrimers with Tripodal Core via Staudinger/Aza-Wittig Reactions

Abstract

Efficient stitching methods for the synthesis of tripodal Fréchet-type dendrimers containing secondary amine as a connector were elaborated. The synthetic strategy involved Staudinger/aza-Wittig reactions (new click reaction) between tripodal tris(azides) and aldehyde-dendrons in toluene in the presence of triphenylphosphine and followed by the reduction of imine intermediates. The tripodal core (1,3,5-tris-(3-azido-propoxy)-benzene) was chosen to serve as the azide functionalities for dendrimer growth. 1,3,5-Tris-(3-azido-propoxy)-benzene was stitched with the aldehyde-functionalized Fréchet-type dendrons via Staudinger/aza-Wittig reactions leading to the formation of the corresponding Fréchet-type dendrimers in high yields.