A convenient stereoselective access to new bis-phosphorylated pyrrolidines and their corresponding nitroxides

Abstract

Addition of one equivalent of dialkylphosphite to γ-diketones yielded new 5-phosphorylated 1-pyrrolines 3. Depending on the experimental conditions, the addition of a second equivalent of dialkylphosphite to 3, led either to (±)-2,5-bis-phosphorylated pyrrolidines 4 or a mixture of (±)- and meso-4. Pyrrolidines 4 were isolated and subsequently oxidized to the corresponding stable (±)- or meso-nitroxides, 5. Coupling of (±)-5a with the prochiral 2-phenyl-ethyl radical was investigated.