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Updated: Jun 10, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Bicyclo[2.1.1]hexanes via Intramolecular Formal (3+2)-Cycloaddition
Alexander S Harmata1, Elene Tatunashvili2,1, Abigail Chang1
1Department of Chemistry, University of Michigan, 930 N University Ave, Ann Arbor, MI, 48109, United States.
This study introduces a new method for synthesizing bicyclo[2.1.1]hexanes using a cycloaddition reaction. The resulting bicyclic imines can undergo photo-induced ring opening for stereochemical control.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
Background:
- Bicyclo[2.1.1]hexanes are strained ring systems with unique structural properties.
- Efficient synthetic routes to these scaffolds are valuable for various chemical applications.
Purpose of the Study:
- To develop a novel intramolecular formal (3+2) cycloaddition for bicyclo[2.1.1]hexane synthesis.
- To explore the scope and limitations of the developed synthetic methodology.
Main Methods:
- Intramolecular formal (3+2) cycloaddition reaction.
- Utilizing allylated cyclopropanes with a 4-nitrobenzimine substituent.
- Employing both activated and unactivated alkenes as reaction partners.
Main Results:
- Successful synthesis of bicyclo[2.1.1]hexanes.
- Demonstrated tolerance of diverse alkene substrates.
- Observed photo-induced ring opening of the bicyclic imine products.
Conclusions:
- The developed cycloaddition provides a new pathway to bicyclo[2.1.1]hexanes.
- The photo-induced ring opening offers a method for epimerization of stereocenters.
- This methodology expands the synthetic toolkit for accessing complex bicyclic structures.
Related Concept Videos
Cycloaddition Reactions: Overview
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Cycloaddition Reactions: MO Requirements for Thermal Activation
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.

