Related Experiment Video
Updated: Jun 15, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Enantiomerically pure polyheterocyclic spiro-beta-lactams from trans-4-hydroxy-L-proline
Giuseppe Cremonesi1, Piero Dalla Croce, Francesco Fontana
1DISMAB-Sezione di Chimica Organica A. Marchesini, Università degli Studi di Milano, V. Venezian 21, I-20133 Milano, Italy.
Abstract:
The "Staudinger ketene-imine reaction" between ketenes generated from natural O,N-protected trans-4-hydroxy-l-prolines and the N-benzyl-N-benzylideneamine led to mixtures of diastereoisomeric, enantiomerically pure pyrrolidine-derived spiro-beta-lactams with a relative cis configuration. These were transformed into the corresponding pyrroline-spiro-beta-lactams by means of treatment with a base and the new C=C double bond was submitted to a number of different reactions in order to evaluate its reactivity and obtain new polyheterocyclic enantiomerically pure spiro-beta-lactams.
Related Concept Videos
Prochirality
¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Stereoisomerism of Cyclic Compounds
Stereochemical Effects of Enolization

![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)