Identification of diamine linkers with differing reactivity and their application in the synthesis of melamine dendrimers

Diamine linkers for the synthesis of dendrimers based on melamine were identified using competition reactions. The relative reactivity of the surveyed cyclic monoamines varies by 40 times, expanding the previously identified series to an overall relative reactivity range of 320 times. Azetidine is 40 times more reactive than the cyclic, nine-membered ring (C8H17N), and 320 times more reactive than benzylamine. Reactivity differences are attributed to pK(a), values and sterics. Diamines incorporating these groups are useful linkers that can be employed in dendrimer synthesis. Specifically, the nucleophilicity of the individual amine groups comprising 3-aminoazetidine, 3-aminopyrrolidine, and 4-aminopiperidine varies by 100 times, 70 times, and 20 times, respectively. These linkers are incorporated into a generation three dendrimer. (C) 2008 Elsevier Ltd. All rights reserved.