Phosphine-Catalyzed Heine Reaction

Significance

Morgan and co-workers report the first phosphine-catalyzed Heine reaction leading to the synthesis of oxazolines 3 in good yield via ring expansion of N-acylaziridine 2. The presence of electron-withdrawing groups on the benzoyl group is necessary to achieve good yields. The authors show that electron-rich phosphines are efficient catalysts for the regioselective rearrangement of aziridines resulting from the nucleophilic attack of the phosphine to the least hindered carbon of the aziridine. The phosphine-catalyzed rearrangement does not proceed with 2,3-disubstituted N-acylaziridines.