Synthesis of Pyrrolidines from Aminoolefins by Hydroamination

Significance

A mild, efficient iron-catalyzed intramolecular hydroamination of aminoolefins to pyrrolidines is reported. The reaction tolerates water, air, and interestingly, halogen substituents. Surprisingly, attempts to extend the methodology to the synthesis of piperidine and azepane derivatives using corresponding chain-extended olefinic sulfonamides gave mixtures of pyrrolidines and piperidines even though 6-exo and 7-exo closures are allowed by Baldwin rules. This is due to double-bond isomerization under the reaction conditions. The scope of this high-yielding method was insufficiently tested although interesting spirobipyrrolidine and pyrrolidino spirotetrahydrofurans were prepared.