High-Loading Dendronized Supports for Solid-Phase Synthesis

In contrast to the structures discussed in the preceding section, which were used as synthetic intermediates and distinguished by the cleavage of the support-dendron bond after their synthesis on support, some of the dendronized insoluble materials are designed as high-loading supports for subsequent solid-phase synthesis. The cleavage that usually follows such synthesis will break the bond between the dendritic termini and substrate and leave the support-dendron bond intact. 

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). 

The utility and versatility of other polyamide dendron-modilied high-loading supports were demonstrated by Chan and coworkers in SPOS of sulfonamides, carboxamides, and other small molecules, as well as by Lee and coworkers in SPOS of pentapeptides.  

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