The syntheses and properties of hyperbranched poly(o-hydroxyamide) [poly(HAB-BCC)-ABP], poly[o-(t-butoxycarbonyl)amide] [poly(HAB-BOC)-ABP-t-BOC], and polybenzoxazole [poly(HAB-cycloBCC)] were examined. Poly(HAB-BCC)-ABP was obtained from the polycondensation reaction of 3,3-dihydroxy-4,4'-diaminobiphenyl (HAB) as an A(2)-monomer and 1,3,5-benzenetricarboxylchloride (BCC) as a B-3-monomer with 2-amino-4-t-butylphenol (ABP) in NMP in the presence of pyridine for 24 h. The reaction of poly(HAB-BCC)-ABP and di-t-buthylcarbonate (DiBOC) was performed to obtain the corresponding poly(HAB-BCC)-ABP-t-BOC with pendant t-BOC groups. The thermal cyclodehydration of poly(HAB-BOC)-ABP-t-BOC was carried out in the film sate at 400 degrees C, affording the poly(HAB-cyclo-BCC) in quantitative yield. Furthermore, the solubilities and thermal properties of these polymers were examined. (c) 2006 Wiley Periodicals, Inc.