Studies of phosphazenes. Part 13. Thermal rearrangement reactions of some methoxycyclophosphazenes

Abstract

The methoxycyclophosphazenes [NP(OMe)₂]_n(n= 3–6) rearrange on heating to give oxocyclophosphazenes, [N(Me)PO(OMe)]_n. Isomeric products are formed when n= 4–6. The ¹H, ³¹P, and ¹³C n.m.r. data for the starting materials and the products are presented. The ethoxy- and n-propoxy-derivatives N₃P₃(OR)₆ do not undergo the above rearrangement. The geminal derivatives N₃P₃R₂(OMe)₄(R = Ph or NHBu^t) on heating yield both fully and partially rearranged products, namely dioxophosphaz-1-enes and oxophosphazedienes, as shown by 270-MHz ¹H n.m.r. spectroscopy. The non-geminal derivative N₃P₃(NMe₂)₂(OMe)₄ gives only the fully rearranged product N₃Me₃P₃(NMe₂)₂O₃(OMe), whose structure has been established from its ¹H and ³¹P n.m.r. spectra.