Fluorinated phosphorus compounds: Part 7. The reactions of bis(fluoroalkyl) phosphorochloridates with nitrogen nucleophiles

Forty bis(fluoroalkyl) phosphoramidates (RFO)2P(O)R were prepared in 10–91% yield by treating phosphorochloridates (RFO)2P(O)Cl where RF was HCF2CH2, HCF2CF2CH2, HCF2CF2CF2CF2CH2, CF3CH2, C2F5CH2, C3F7CH2, (CF3)2CH, (FCH2)2CH and (CH3)2CF3C with nucleophiles HR, where R was NH2, NHMe, NMe2, NHEt and NEt2 in diethyl ether at 0–5 °C. The bulky chloridate [(CH3)2CF3CO]2P(O)Cl reacted with ammonia, methylamine, dimethylamine and ethylamine, but not with diethylamine—even on heating in the presence of 4-dimethylaminopyridine—due to steric hindrance at phosphorus. Fluorinated phosphoramidates have lower basicity and nucleophilicity than their unfluorinated counterparts: (EtO)2P(O)NH2 is more easily hydrolysed by HCl than (CF3CH2O)2P(O)NH2 and whereas, (EtO)2P(O)NH2 is known to react with oxalyl chloride and thionyl chloride to give (EtO)2P(O)NCO and (EtO)2P(O)NSO respectively, (CF3CH2O)2P(O)NH2 reacted only with oxalyl chloride to give (CF3CH2O)2P(O)NCO in 10% yield. Two other new fluorinated species, (CF3CH2O)2P(O)NHOMe and (CF3CH2O)2P(O)N3, were prepared by nucleophilic substitution of bis(trifluoroethyl) phosphorochloridate with methoxyamine and azide ion.