For the purpose of reducing the induction period of the ring-opening polymerization of N-methyl-1,3-benzoxazines, several urethanes were examined as promoters. The examined promoters 3a-d were the adducts of resorcinol and phenyl isocyanate, that of bisphenol A and phenyl isocyanate, that of resorcinol and butyl isocyanate, and that of 1,3-propanediol and phenyl isocyanate, respectively. The aromatic urethanes 3a and 3b, which were adducts of the phenolic compounds and phenyl isocyanate, exhibited significant promoting effects. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2183-2190, 2011