Dendrimer interior functional group conversion and dendrimer metamorphosis--new approaches to the synthesis of oligo(dibenzyl sulfone) and oligo(phenylenevinylene) dendrimers

A series of G1] to G3]-oligo(dibenzylsulfide) dendrimers containing up to 21 interior dibenzylsulfide moieties was prepared as starting materials toward the syntheses of two new series of oligo(dibenzyl sulfone) and oligo(phenylenevinylene) dendrimers using two different dendrimer-to-dendrimer conversion strategies. The first strategy entailed the interior functionalization of the G1] to G3]-oligo(dibenzylsulfide)s to the corresponding G1] to G3]-oligo(dibenzyl sulfone)s via hydrogen peroxide oxidation. Successful conversions of up to 21 interior dibenzylsulfide moieties to the corresponding dibenzyl sulfone groups were demonstrated. The second involved the skeletal rearrangements, also named as dendrimer metamorphosis, of the G1] and G2]-oligo(dibenzyl sulfone) dendritic backbones to the corresponding G1] and G2]-oligo(phenylenevinylene)s dendrimers via the Ramberg-Backlund (RB) reaction. Up to nine RB rearrangements on a dendrimer skeleton were realized and the conversion efficiency of each single RB rearrangement reaction was found to be 96%.