Synthesis of segment-block dendrimers via chemical ligation

Abstract

Dendrimers are unique, monodisperse macromolecules with well defined structureand molecular weight arising from their multi-step, iterative synthesis. Recently, they havebeen utilized for drug delivery applications. The aim of this study is to synthesize block dendrimers which consist of two different dendritic constituents (dendrons).Potentially, one constituent of a particular block dendrimer can be designed as the drug carrier and theother constituent can bear targeting functionality. "Chemical ligation" (thiaproline ligation)is employed for the coupling of the dendrons. "Thiaproline ligation" is an efficient coupling method designed for peptide synthesis. It does not require any reagents, works in aqueousmedia at room temperature with high yields. This method seems to be useful for couplingof two different dendrons to obtain a segment-block dendrimer for further applications.Two different dendrons, poly(amido amine) and polyether dendrons, were synthesized via divergent method up to fourth generation and convergent method up tosecond generation respectively. These dendrons were equipped with the necessaryfunctional groups and "thiaproline ligation" was utilized for the coupling of dendrons. Allcompounds were identified by IR, 1H NMR and 13C NMR spectroscopy techniques.