One-pot synthesis of dendritic polyamide. 2. Dendritic polyamide from 5-[3-(4-aminophenyl)propionylamino]isophthalic acid hydrochloride

Dendritic polyamides having a high degree of branching and a narrow polydispersity were synthesized by a "one-pot" procedure which consists of successive activation of carboxyl groups followed by condensation with an aminodicarboxylic acid, as the AB(2) monomer. 5-[3-(4-Aminophenyl)propionyl-amino]isophthalic acid hydrochloride (4) was used, as the AB(2) monomer, without a protecting group. The carboxyl group of trimesic acid (8) was activated with an equimolar condensing agent diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (DBOP) to produce the corresponding active amides 1,3,5-benzenetris(3-carbonylbenzoxazoline-2-thione). Then, 3 equiv of 4 was added to 8 and condensed. The dendritic polyamides were synthesized divergently by repeating these activations and condensations. The terminal carboxyl groups were end-capped by diethylamine and the products were isolated. Dendritic polyamides obtained were characterized by IR and NMR spectroscopies and GPC. Number-average molecular weights (M-n) of dendritic polyamides estimated by the end group analysis were in good agreement with the calculated values. The degrees of branching and the polydispersities M-w/M-n were 0.8-0.9 and 1.2-1.5, respectively.