This investigation deals mainly with the synthesis of new phosphorus-nitrox
ide free radicals. Nitroxides with a beta -(31) P group were synthesized fr
om the aldo-nitrones alpha-phenyl-N-tert-butylnitrone and 5,5-dimethyl-1-py
rroline-N-oxide (DMPO) as well as the keto-nitrones 2,5,5-trimethyl-1-pyrro
line-N-oxide (2,5,5-M3PO) and 2-phenyl-5,5-dimethyl-1-pyrroline-N-oxide (2-
Ph-DMPO). Three different routes were explored. The first two routes involv
ed nitronyl spin trapping of phosphorus-centred radicals generated thermall
y or photochemically by hydrogen abstraction by tert-butoxyl radicals from
di-tert-butyl peroxyoxalate or from photoexcited benzophenone, respectively
. The third approach used the addition of phosphorus anions (generated by t
he strong, hindered base lithium diisopropylamide) to the nitrones and subs
equent one-electron oxidation to the corresponding nitroxides. The most nov
el feature of the work presented here may be the synthesis of beta-phosphor
anyl [P(OR)(4)] nitroxide spin adducts. For comparison purposes the related
beta-phosphityl [P(O)(OR)(2)] nitroxides were also assembled and character
ized by ESR spectroscopy. Copyright (C) 1999 John Wiley & Sons, Ltd.