Polyamidourea dendron

Scheme 15.13. Synthesis of polyamidourea dendrons on solid support.

With the polyamidourea dendrons the increase in loading was even more dramatic (up to 230 nmol/bead). The high per-bead loading of the terminal functional groups enabled the analysis of compounds cleaved from a single bead for these dendrons (e.g., biaryls prepared on the resin were analyzed by HPLC and NMR). 

In order to investigate dendrimers of a different nature [230], Bradley described the synthesis and transfection efficiency of polyamidourea dendrimers synthesised from isocyanate-containing AB3 monomers [231-234]. The use of this kind of tris-branched building block was addressed to enhance dendrimer synthesis by replacement of the 1,4-addition step typical of PAMAM synthesis and to a rapid increase in terminal functionality. The dendritic structures were synthesised using a divergent, microwave-assisted, solid-phase approach with the dendrimers assembled on polystyrene resin via an acid labile linker (see Fig. 26). In particular, a G3.0 polyamidourea bis-dendron with the peripheral amino groups conjugated to L-lysine residues demonstrated remarkable transfection abilities [234],... 

Fig. 26 Solid-phase synthesis of a lysine-capped G3.0 polyamidourea 1—>3 C-branched bis-dendron...

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