Synthesis of Fréchet-type poly(aryl ether) dendrimers with allyl end groups: comparative convergent and divergent approaches

Nancy E Magaña-Vergara,Rebeca Yépez,Delia Soto-Castro,Hugo Vazquez-Lima,Rosa Santillan

doi:10.24820/ark.5550190.p009.994

Abstract

Synthesis of Fréchet-type poly(aryl ether) dendrimers with allyl end groups: comparative convergent and divergent approaches

Highlights

In a recent communication[1] our group reported the synthesis of Fréchet-type poly(aryl ether) dendrimers that incorporate the 1,3,5-triphenylbenzene as core molecule and 3, 6, 9, or 12 terminal allyl ether groups using a convergent approach
Motivated by potential applications of poly(aryl ether) dendrimers with allyl ether end groups such as preparation of cross-linked dendrimeric materials via ring closing metathesis reactions,[2,3,4,5] the advantage of selective removal of the protecting groups with Pd catalysts to provide peripheral hydroxyl groups that can be functionalized with hydrophobic chains to form new supramolecular polymers,[6] but mainly because these groups are active for hydrosilylation reactions to obtain metallodendrimers with high-boron-content that can be applied in boron neutron capture therapy (BNCT),[7] we have continued working on the synthesis of dendrimers with allyl ether terminal groups
To this end we explored both convergent and divergent methodologies, finding that the latter approach provides higher yields, probably due to the electronic effects on the transition states that limit the step of the alkoxide attack to the alkyl halide, according to molecular mechanics and DFT calculations

Summary

Introduction

In a recent communication[1] our group reported the synthesis of Fréchet-type poly(aryl ether) dendrimers that incorporate the 1,3,5-triphenylbenzene as core molecule and 3, 6, 9, or 12 terminal allyl ether groups using a convergent approach. In this paper the synthesis of Fréchet-type poly(aryl ether) dendrimers of the first and second generation containing 6 and 12 terminal allyl ether groups is described. The aim of this study was to establish the best conditions for the synthesis of this type of dendrimer To this end we explored both convergent and divergent methodologies, finding that the latter approach provides higher yields, probably due to the electronic effects on the transition states that limit the step of the alkoxide attack to the alkyl halide, according to molecular mechanics and DFT calculations

Objectives

Results

Conclusion