Synthesis, reactivity and structures of spirocyclic products derived from octachlorocyclotetraphosphazene: Comparison with spirocyclic cyclotriphosphazenes and linear phosphazenes

Abstract

The reaction of N4P4Cl8 1 with the difunctional reagents 2,2′-methylenebis(4,6-di-tert-butylphenol) (as its disodium salt) and N,N′-diisopropylpropane-1,3-diamine gave the spirocyclic products 2,2-N4P4{[O-4,6-(t-Bu)2C6H 2]2CH2}Cl6 4 and 2,2-N4P4[N(i-Pr)CH2CH2CH 2N(i-Pr)]Cl6 5. Further reaction of 1 with 2 mol equivalents of N,N′-diisopropylpropane-1,3-diamine afforded the novel dispiro derivative 2,2,6,6-N4P4[N(i-Pr)CH2CH2CH 2N(i-Pr)]2Cl4 6. Whereas the analogous reaction of N3P3Cl6 2 with the above diamine gave the monospiro derivative 2,2-N3P3[N(i-Pr)CH2CH2CH 2N(i-Pr)]Cl4 7 readily, the reaction of 2 with the diols CH2[4,6-(t-Bu)2C6H2OH]2 or CH2(4-Me-6-t-BuC6H2OH)2 is sluggish. In the case of the latter diol, a product formulated as N3P3[O-4-Me-6-t-BuC6H 2-4-Me-6-t-BuC6H2OH]Cl5 9 was identified (31P NMR). The linear phosphazene Cl2P(O)N=PCl3 3, by contrast, reacted with CH2(4-Me-6-t-Bu-C6H2OH)2 and Et3N to give the cyclic product Cl2P(O)N=P[(O-4-Me-6-t-BuC6H2) 2CH2]Cl 8. Reaction of the spirocycle 5 with an excess of MeNH2/Et3N afforded the new bicyclic phosphazene containing a spirocyclic ring N4P4[N(i-Pr)CH2CH2CH 2N(Z-Pr)](NHMe)4(NMe) as a crystalline solid. The crystal structures of 4·0.5C4H8Cl2 and 5-8 have been determined.