Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

Abstract

The synthesis and characterization of a series of per-substituted spermine-bridged cyclophosphazene derivatives are reported based on the known compound [N3P3X4(NHCH2CH2CH2N)CH2CH2](2), (1a) (where X = Cl), to give a number of new compounds (1b-1h) in which X = OPh, [spiro-O(CH2)(3)O](0.5), OCH2CF3, NHPh, NC4H8, Ph and NHBu', respectively. Two synthetic routes were utilized: (i) using the chloro-precursor 1a in nucleophilic substitution reactions with a variety of anionic and neutral nucleophiles to give compounds 1b-1f and (ii) reaction of spermine with the appropriate di-gem tetrasubstituted cyclophosphazene to give compounds 1g and 1h. Bridged compounds such as 1a-1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a. (C) 2004 Elsevier B.V. All rights reserved.