(2-Furanylmethyl)spiro(N/N)cyclotriphosphazenes and some quaternized derivatives: syntheses, structural elucidation and free radical scavenging activity studies

Abstract

In the present study, the reaction of hexachlorocyclotriphosphazene (N3P3CI6, HCCP) and N1,N2-bis(2-furanylmethyl)-1,2-diaminoethane (1) yielded the tetrachloro-spiro(ethane-1,2-diamino)-N,N-bis(2-furanylmethyl)cyclotriphosphazene (2). Tetrachlorocyclotriphosphazene (2) was then converted to fully substituted cyclotriphosphazenes (2a-2e) using secondary amines and sodium dimethylaminoethoxide. Compound 2e with dimethylaminoethoxy chains was quaternized in substituted nitrogen by reacting with methyl iodide (CH3I) to give polyiodo salt (2f). Subsequent metathesis with bis(trifluoromethane)sulfonimide lithium salt (LiNTf2) gave the corresponding ionic salt (2 g). This phosphazene-based amide salt (2 g) arose as a viscous liquid at room temperature. The structures of 2–2 g were confirmed by elemental analysis, HRMS, FT-IR, 1H, 13C, and 31P NMR data. The crystal structures of 2 and 2b were also elucidated by X-ray crystallography. Additionally, the antioxidant activities of the phosphazene derivatives were investigated using free radical scavenging assays. The highest radical scavenging activity values (%) were detected for compounds 2e (53.4 ± 0.4) and 2f (56.1 ± 0.2).