Multivalent 4-nitrophenyl (PNP)-carbonate esters were prepared from carbona
te ester-containing core groups by a new divergent-growth process. The proc
ess doubles the number of PNP-carbonate esters with each round of growth, o
r branching, which occurs by reacting an N,N-dihydroxylalkyl amine with a P
NP-carbonate ester. The resulting N,N-dihydroxyalkyl carbamate contains two
hydroxyl groups for each original PNP-carbonate ester. The hydroxyl groups
are converted in situ to PNP-carbonate esters, and the process can be repe
ated to provide successive generations of dendrimer-like branched structure
s of increased valence. (C) 2001 Published by Elsevier Science Ltd.