An allyl-containing diphenol, 1-(3-allyl-4-hydroxyphenyl)-1-(4-hydoxyphenyl)-1-(6-oxido-6H -dibenz[c,e][1,2]oxaphosphorin-6-yl)ethane (1), was prepared from a one-pot reaction of 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide, 4-hydroxyacetophenone, and 2-allylphenol in the presence of p-toluenesulfonic acid monohydrate. Then, an allyl-containing dietheramine, 1-(4-(4-aminophenoxy)phenyl)-1-(3-allyl 4-(4-aminophenoxy)-phenyl)-1-(6-oxido-6H-dibenz[c,e][1,2] oxaphosphorin-6-yl)ethane (3), was prepared from the nucleophilic substitution of (1) with 4-fluoronitrobenzene, followed by the reduction of the dinitro groups by Fe/HCl. A flexible polyetherimide (PEI) (4) with a curable characteristic was prepared from the condensation of (3) and 4,4-oxydiphthalic anhydride (ODPA) in m-cresol in the presence of isoquinoline. Curing PEI (4) at 300 degrees C leads to PEI (5), which exhibits much a higher Tg value (307 degrees C) and a lower coefficient of thermal expansion (CTE) (29 ppm/degrees C) than PEI (4) (Tg = 253 degrees C, CTE 52 ppm/degrees C). (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 1734-1741