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Updated: May 12, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Base-Promoted C→N Carbonyl Shift Enables One-Step Access to aza-β-Lactams from α-Heteroaryl-α-amino Esters
Jozef Kristek1, Nikola Št'astná1, Jiří Pospíšil1,2,3
1Department of Organic Chemistry, Faculty of Science, Palacký University, tř. 17. listopadu 1192/12, Olomouc CZ-771 46, Czech Republic.
Abstract:
Aza-β-lactams arise directly from α-heteroaryl-α-amino esters through an iPrMgCl-promoted C→N carbonyl shift, hydroxylamine capture, and [1,2]-heteroaryl migration. The reaction proceeds in one step, scales to grams, tolerates diverse Cα-alkyl groups and hydroxylamines, and reveals a predictable divergence to five-membered ureas under strongly basic conditions or with electron-poor N-substituents. Isolation and productive re-entry of a carbamate intermediate support a reversible manifold preceding migration and rationalize racemic product formation.
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