Phosphorus-Nitrogen compounds part 47: The conventional and microwave-assisted syntheses of dispirocyclotriphosphazene derivatives with (4-fluoro/4-nitrobenzyl) pendant arms: Structural and stereogenic properties and DNA interactions

Abstract

The Cl exchange reactions of hexachlorocyclotriphosphazene, N3P3Cl6, with two equimolar amounts of N-alkyl-N′-mono(4-fluorobenzyl)diamines (1–3), FC6H4CH2NH(CH2)nNHR1 (n = 2 and 3, R1 = CH3 or C2H5), and N-alkyl-N′-mono(4-nitrobenzyl)diamines (4 and 5), NO2C6H4CH2NH(CH2)nNHR1 (n = 2, R1 = CH3 or C2H5), led to the formation of the mono(4-fluorobenzyl) (1a-3a) and mono(4-nitrobenzyl) (4a and 5a) spirocyclotriphosphazenes as minor products, and trans-bis(4-fluorobenzyl) (1b-3b) and trans-bis(4-nitrobenzyl) (4b and 5b) spirocyclotriphosphazenes as major products. The bis(4-fluorobenzyl)spirocyclotriphosphazene (1b) reacted with excess pyrrolidine to give fully substituted (1c) phosphazene. The structures of the new compounds were elucidated by elemental analyses, ESI-MS, FTIR, 1H, 13C, and 31P NMR techniques. The molecular and crystal structures of 1a, 3b and 6 were identified by single crystal X-ray crystallography. The absolute configurations of 3b and 6 were unambiguously established as SS and R respectively, using X-ray crystallographic data. On the other hand, the interactions of 1b, 1c, 3b-5b and 6 with plasmid DNA indicated that compounds 3b, 4b, and 5b caused a decrease in the mobilities and intensities of form I and form II DNA. Compounds 1b, 1c and 6 caused a double strand break of plasmid DNA. All of the tested compounds inhibited enzyme cleavage indicating compound bindings to the specific G/G and A/A nucleotides.