The reaction of diethyl 3-bromopropylphosphonate with phosphorus pentachloride in carbon tetrachloride gave ethyl 3-bromopropylphosphonochloridate, which upon reaction with anhydrous methylamine at -15� gave ethyl N-methyl-P-3-bromopropylphosphonamidate. Treatment of this phosphonamidate with sodium hydride in boiling xylene gave 2-ethoxy-1-methyl-l,2-azaphospholidine 2-oxide. Some other possible routes to this compound were investigated.