Fluorinated phosphorus compounds: Part 8. The reactions of bis(fluoroalkyl) phosphorochloridates with sulfur nucleophiles

The reactivity of bis(fluoroalkyl) phosphorochloridates to nucleophiles is summarised. Previous data and the results described here indicate that reactivities decrease in the order: amines>alcohols>thiols. The synthesis of CF3CH2OP(O)(SEt)2 in 30% yield was accomplished by treating CF3CH2OP(O)Cl2 with two molar equivalents of EtSH and Et3N in ether. The chloridates (CF3CH2O)2P(O)Cl and (C2F5CH2O)2P(O)Cl did not react with MeSH in ether at −78 °C or when heated with Pb(SMe)2 in benzene. Ethanethiol and propanethiol reacted with fluorinated chloridates in the presence of triethylamine to give thiolates (RFO)2P(O)SR in 13–41% yield where RF was CF3CH2, C2F5CH2, C3F7CH2 or (CF3)2CH and R was Et or n-Pr. Similarly, reaction of phosphorobromidates (RFCH2O)2P(O)Br, made by brominating the corresponding bis(fluoroalkyl) H-phosphonates, with benzenethiol gave derivatives (RFCH2O)2P(O)SPh in 43 and 46% yield where RF was CF3 and C2F5, respectively. Treatment of the chloridothiolate Cl(EtO)P(O)SMe, prepared in two steps from triethyl phosphite, with fluoroalcohols and triethylamine in ether gave species RFO(EtO)P(O)SMe in 62–74% yield where RF was CF3CH2, C2F5CH2, C3F7CH2 or (CF3)2CH. The reactions of bis(trifluoroethyl) phosphorochloridate with 2-mercaptoethanol, 3-mercaptopropanol and ethane-1,2-dithiol gave several unexpected products whose structures were tentatively assigned.