A Convenient method for the synthesis of fused phosphorusheterocycle 1,3,2-oxazaphosphorin-[3,2-a]-8-oxo-10-thio(or seleno)-[1,3,2]-benzodiazaphosphorines was carried out in one pot by the reaction of Tris(diethylamino)phosphine with multifunctional compounds 2-(N-(βor γ-hydroxyl) alkylene) amino-benzamides 1.When PCL3 was used, only chlorinated product was obtained.