DEPMPO and lipophilic analogues:: synthesis and EPR studies

DEPMPO (5-diethylphosphono-5-methyl-1-pyrroline N-oxide) is now recognised as a major trap for the applications of spin-trapping techniques in biological milieu. We report herein a new synthetic route for DEPMPO ending with the reductive cyclisation of the phosphorylated gamma-nitroaldehyde 8. In comparison with the usual synthesis of DEPMPO, involving the oxidation of the parent pyrrolidine 3, the new approach avoids the formation of over oxidation by-products thus making easier the purification of DEPMPO. Lipophilic analogues of DEPMPO have been prepared through addition of various Y2P(O)H on 2-methyl-1-pyrroline, followed by oxidation of the ensuing pyrrolidines. These new nitrones were used to trap different radicals in water and organic solvents.