New Route to Azaspirocycles via the Organolithium-Mediated Conversion of β-Alkoxy Aziridines into Cyclopentenyl Amines

A new three-step route to azaspirocycles involving the organolithium-mediated conversion of β-alkoxy aziridines into substituted cyclopentenyl amines, hydroboration, and cyclization has been developed. The methodology is utilized in the construction of the pentacyclic ring system of cephalotaxine.