The click-coupling reaction was applied to polycondensation, to synthesize a high-molecular weight prepolymer having benzoxazine moieties in the main chain. For the polycondensation, a bifunctional N-propargyl benzoxazine was synthesized from bisphenol A, propargylamine, and formaldehyde. The propargyl group was efficiently used for the copper(I)-catalyzed alkyne-azide "click" reaction with p-xylene-alpha,alpha'-diazide, to give the corresponding linear polycondensate having 1,2,3-triazole junctions. The polycondensation proceeded in N,N-dimethylformamide (DMF) at room temperature. By this highly efficient "click-" polycondensation reaction, the benzoxazine ring in the monomer was successfully introduced into the polymer main chain without any side reaction. The obtained polymer (=prepolymer) underwent thermal crosslinking to afford the corresponding product, which was insoluble in a wide range of organic solvents and exhibited higher thermal stability than the polymer before crosslinking. (C) 2008 Wiley Periodicals, Inc.