Related Experiment Video
Updated: Jul 17, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Construction of bicyclic ring systems via a transannular SmI2-mediated ketone-olefin cyclization strategy
Gary A Molander1, Barbara Czakó, Michael Rheam
1Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA. gmolandr@sas.upenn.edu
Abstract:
The development of novel methods and strategies for the formation of polycyclic ring structures is of utmost importance in organic synthesis. The present study describes the investigation of a transannular cyclization strategy for constructing bicyclic ring systems. To test the viability of the approach, the SmI2-mediated ketone-olefin coupling reaction, a method previously developed in this laboratory, was examined. Investigation of the transannular cyclization of cyclooctene, cyclodecene, and cycloundecene derivatives revealed that the process proceeds with high yield and diastereoselectivity, and in the case of larger ring-sized compounds, with excellent regioselectivity. The regioselectivity of the annulation process could be rationalized based on examining the low energy conformations of the keto alkene starting materials. These results demonstrate the efficiency and the potential of the transannular cyclization tactic for the creation of bicyclic ring systems.
Related Concept Videos
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Cycloaddition Reactions: Overview
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
