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Updated: May 9, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Experimental evidence of a cyclopropylcarbinyl conjugative electronic effect
Phyllis A Leber1, Anthony J Nocket, Matthew F Wipperman
1Department of Chemistry, Franklin & Marshall College, Lancaster, PA, USA. phyllis.leber@fandm.edu
Abstract:
Bicyclo[3.2.0]hept-2-enes undergo thermal rearrangement to norbornenes via diradical transition structures. The synthesis of exo-7-cyclopropylbicyclo[3.2.0]hept-2-ene has been achieved by cycloaddition of cyclopentadiene and cyclopropylketene, generated by treatment of cyclopropylacetyl chloride with triethylamine. A comparison of the cyclopropyl substituent effect with that of other C7 substituents provides experimental evidence of an electron-donating conjugative effect on the transient diradical transition structure in the thermal reaction of exo-7-cyclopropylbicyclo[3.2.0]hept-2-ene.
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