Synthesis of Tetraalkyl (Pyrrolidine-2,2-diyl)bisphosphonates and 2,2-Bis(diethoxyphosphoryl)-3,4-dihydro-2H- pyrrole 1-Oxide; ESR Study of Derived Nitroxides

2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide: evaluation of the spin trapping properties

“…Then, in order to clarify the role played by the phosphorus moiety in the stabilization of the superoxide spin adduct, we prepared the 2-(diethoxyphosphorylmethyl)-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide 3 in which the p3 phosphorus group is separated from the nitrone moiety by a methylene spacer [7]. The ESR experiments driven with 3 showed that the overall characteristics of this nitrone in the spin trapping of oxygen-centered radicals are closer to that of DMPO rather than to that of DEPMPO, thus indicating the importance of the strong electron-withdrawing effect of the phosphorylated group [8] [9]. In the present paper, we report the results of our work on the synthesis of the 2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide 5 (EMPO) (scheme 1) and on the characteristics of this nitrone as free radical trap.…”

Synthetic Procedures Leading towards Aminobisphosphonates

“…Unfortunately, primary amides are not suitable substrates for this reaction [38]. The use of triethyl phosphite and phosphoryl chloride appeared to be especially useful when lactams were used as substrates, resulting in high yields of aminomethylenegem-bisphosphonates (Scheme 5) [36][37][38][39]. They were readily hydrolyzed, yielding corresponding bisphosphonic acids (representative example compound 5).…”

“…Another possibility is using trialkyl or trimethylsilyl phosphites in reactions prompted by phosphoryl chloride [36][37][38][39], trifluoromethanesulphonic anhydride (Tf2O) [40], zinc chloride [41] or trimethylsilyl trifluoromethanesulfonate [42,43]. Unfortunately, primary amides are not suitable substrates for this reaction [38].…”

Synthesis of New Tetraethyl(N-alkyl-1-aminoethan-1,1-diyl)bisphosphona-tes and ESR Analysis of Chemical Exchange of Derived Nitroxides of Acyclic Aminobisphosphonates

“…It uses a one step reaction that has been described elsewhere. [5][6][7] At -7.5 °C under nitrogen atmosphere POCl3 (2 mol.) is slowly added to a mixture of the corresponding amide (1 mol.…”