Syntheses and study of a pyrroline nitroxide condensed phospholene oxide and a pyrroline nitroxide with diphenylphosphino moiety

The reaction of a diene nitroxide precursor with dichlorophenylphosphine in a McCormac procedure afforded pyrroline nitroxide condensed phospholen oxide. Lithiation of the protected 3-bromo-pyrroline nitroxide followed by treatment with chlorodiphenylphosphine after deprotection afforded (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine oxide, and after reduction, (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine was realized, which was also supported by X-ray single crystal diffraction measurements. This pyrroline diphenylphosphine derivative was converted to hexadecylphosphonium salt, which was more effective antineoplastic agent than its analogue MITO-CP.