Two-step approach towards the accelerated synthesis of dendritic macromolecules

The accelerated synthesis of regular dendritic poly (ether-urethane) macromolecules through growth of two generations in a single synthetic operation has been explored. This procedure requires the use of two AB2 monomers such as 3,5-diisocyanatobenzyl chloride and 3.5-dihydroxybenzyl alcohol that can react pairwise in a one-pot sequential addition procedure. The two monomers are added stepwise to a previously formed first-generation dendrimer to produce a third-generation dendritic molecule without any need for intermediate purification or activation procedures. When 3,5-dihydroxybenzyl alcohol is used as the second monomer, some irregular growth is seen due to the occurrence of a side reaction involving transesterification of the carbamic ester moiety. The side reaction can be avoided if 3,5dihydroxybenzyl alcohol is replaced by methyl 3,5-dihydroxybenzoate.