title: A spiro to ansa rearrangement in cyclotriphosphazene derivatives.
abstract: Nucleophilic substitution reactions of cyclotriphosphazene derivatives having five-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(2)X] (X = NH or O) with alkoxides (of tetraethylene glycol and some mono-functional alcohols) give unexpected rearrangements to form stable seven-membered ring ansa compounds, even though crystallographic evidence shows ring distortion and compression of the cyclophosphazene ring. With weaker nucleophiles such as sodium phenoxide and pyrrolidine substitution at a PCl2 group is preferred and no rearrangement takes place. In contrast, reactions of the analogous phosphazenes containing six-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(3)X], with all of the above reagents give only normal substitution reactions at the PCl2 moieties and no rearrangement products. The spiro to ansa rearrangements in cyclophosphazenes are remarkable as the reported primary reaction products with the same difunctional reagents HO(CH(2))(2)XH are predominantly spiro, with some dangling and bridging derivatives, but no ansa compounds.
authors.affiliation: Department of Chemistry, Gebze Institute of Technology, Gebze, Kocaeli, Turkey. besli@gyte.edu.tr
authors.forename: Serap
authors.initials: S
authors.lastname: Beşli
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Coles
authors.forename: David B
authors.initials: DB
authors.lastname: Davies
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hursthouse
authors.forename: Adem
authors.initials: A
authors.lastname: Kiliç
authors.forename: Robert A
authors.initials: RA
authors.lastname: Shaw
mesh_terms: D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D009943:Organophosphorus Compounds / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*
chemical_list: D009943:Organophosphorus Compounds; D013141:Spiro Compounds