Synthesis and Reactivity of 1-Pyrroline-5-carboxylate Ester 1-Oxides

Some C5 mono- and diester-substituted 1-pyrroline-1-oxides have been prepared via reductive cyclisation of the corresponding γ-nitro carbonyl compounds. Ethyl 2-phenyl-1-pyrroline-1-oxide-5-carboxylate 5c was regioselectively alkylated at C5. Acylation of this molecule occurs exclusively on the nitrone oxygen and leads to C3 substituted pyrrolines as the result of a hetero-Cope rearrangement.