Synthesis of 3,4-Disubstituted Pyrroline Nitroxides Containing Diphenylphosphane or Diphenylphosphane Oxide Substituents

(Methyl 4-(diphenylphosphoryl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole-3-carboxylate-1-yl)oxydanyl was obtained as a keyintermediate of the reaction starting from 3,4-dibromo-2,2,5,5-te-tramethyl-2,5-dihydro-1H-pyrrol-1-yloxydanyl or (methyl 2,2,5,5-te-tramethyl-2,5-dihydro-1H-pyrrole-3-carboxylate-1-yl)oxidanyl. This key compound could be converted into an azido-specific Staudinger ligation-inducing spin label, amino- and thiol-specific spin label, or MITO-CP-like antiproliferative agent