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, H-1 and P-31 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 S(N)2 mechanism. Compound 3 might be formed by both S(N)1 and S(N)2 reaction mechanisms, respectively. These mechanisms were supported by P-31 NMR and X-ray crystallography results. (C) 2013 Elsevier B.V. All rights reserved.