Synthesis and properties of a new class of polyether dendritic fragments: Useful building blocks for functional dendrimers

Polyether dendritic sectors 1-4 from the first to the fourth generations, respectively, were prepared by a convergent approach from readily available 4-tert-butylphenol, phloroglucinol and 1,3-dibromopropane. Using a three-step iterative synthetic sequence involving mono-O-alkylation of [Gn]-OH with excess 1,3-dibromopropane, bis-O-alkylation of the resulting compound with 5-benzyloxyresorcinol 5 followed by hydrogenolysis with palladium catalyst, [G(n+1)]-OH of the next higher generation could be prepared in good yields. These dendritic sectors have good solubility properties and are inert in both acidic and basic media, and do not show any redox behaviour from -2.0 to +1.9 V. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.