Investigation of nucleophilic substitution pathway for the reactions of 1,4-benzodioxan-6-amine with chlorocyclophosphazenes

In the present work, a series of 1,4-benzodioxan-6-amino substituted cyclophosphazenes (1–8) were synthesized in order to provide insight into the reaction mechanism for nucleophilic substitution. All compounds were fully characterized by elemental and mass analyses, 1H and 31P NMR spectroscopies. Molecular and crystal structures of 1, 2, 4, 7a and 7c were characterized by X-ray crystallography. While compounds 2 and 4 could be formed by a proton abstraction/chloride elimination mechanism, 1, 6, 7a and 7c could be formed by SN2 mechanism. Compound 3 might be formed by both SN1 and SN2 reaction mechanisms, respectively. These mechanisms were supported by 31P NMR and X-ray crystallography results.