Reactions of ansa fluorodioxy cyclotriphosphazene derivatives with phenol

The reactions of mono ansa fluorodioxy cyclotriphosphazenes {N3P3Cl4[OCH2(CF2)nCH2O] (n = 3, 1a; n = 4, 1b)} with the sodium salt of phenol in THF solution at different molar ratios were investigated in order to determine the reaction pathways and the mechanism of the nucleophilic substitution at the PCl2 and PCl(OR) phosphorus atoms by phenol and for a comparison with previous work on the reactions of the same starting compounds 1a and 1b with the sodium salt of methanol. Fourteen new products were formed, namely mono-phenoxy derivatives (2a–4a, 3b), di-phenoxy derivatives (5a–7a, 5b), tri-phenoxy derivatives (8a–10a, 8b) and tetra-phenoxy derivatives (11a, 11b). These products, which could be separated, have been characterized by elemental analysis, mass spectrometry, 1H and 31P NMR spectroscopy. A similar result to the reaction with methanol was observed in the first stage of the reaction of compound 1a, containing the 10-membered ansa-ring, with the reaction occurring competitively at both the PCl2 and P(OR)Cl moieties with an approximate 8:1 preference for the PCl2 group. In the second stage of the reaction of compound 1a, the bis non-geminal cis compound (7a) formed as the major product, whilst the major product was the bis gem compound in the similar reaction of 1a with sodium methoxide. Consequently, the tris non-geminal cis compound (9a) might be formed beside the tris geminal compound (8a) in the third stage of the reaction of compound 1a with phenol, unlike the methanol reaction. All the reactions of compound 1b, containing the 11-membered ansa-ring, with the sodium salt of phenol occurred at the PCl2 group before the P(OR)Cl moiety. X-ray crystallographic studies of two compounds (7a and 8b) showed that nucleophilic substitution reactions with the sodium salt of phenol at the ansa-ring PCl(OR) phosphorus atoms of the mono ansa fluorodioxy cyclotriphosphazene compounds 1a and 1b occurred with retention of the configuration.

Graphical abstractMono ansa fluorodioxycy clotriphosphazenes {N3P3Cl4[OCH2(CF2)nCH2O] (n = 3, 4) were reacted with the sodium salt of phenol in different molar ratios and the isomer distributions and reaction pathways were determined.Figure optionsDownload full-size imageDownload as PowerPoint slide