Improved Iterative Synthesis of Linearly Disassembling Dendrons

We report a significant improvement in the synthesis of disassembling dendritic structures by using 4-hydroxy-3-nitrobenzoic acid as the building block. We have prepared multigram quantities of first-through third-generation linearly disassembling dendrons containing a [3-N,4-O]-benzylaryl ether disassembly pathway, capped by a vanillin-derived phenyl allyl ether trigger, and a p-nitrophenoxy (PNP) reporter group. The disassembly process of these materials was initiated by allyl deprotection and monitored by the absorbance of the PNP reporter unit in the UV-vis. Modification of the disassembly conditions for the ally] trigger resulted in decreased disassembly times, decreased incubation time for onset of disassembly from minutes to seconds, and allowed observation of indicative rate differences between generations not seen with the previously reported conditions.