1,3-Bridged cyclopropenes

Eliminations Involving Carbon–Halogen Bonds and Leading to Highly Strained Rings

“…The dehalosilylation can be carried out in the gas phase over solid tetra-n-butylammonium fluoride deposited on glass helices, and even 59 can be transferred to a cold finger and trapped with cyclopentadiene, or as a remarkably stable ene-dimer 44,128 .…”

Regio‐ and Stereoselectivity of Ene Reactions: The Dimerization of Bicyclic 1,3‐Fused 2‐(Trimethylsilyl)cycloprop‐1‐enes

“…Based on 1 H NMR and mass spectra, Billups and co-worker reported that compound 3 (n = 5) underwent ene dimerization and trimerzation, but the regio-and stereochemistry were not clear. [11] We wish to report herein that two bicyclic 1,3-fused 2- (7)] as the sole products. The regio-and stereochemistry of these ene reactions have been confirmed by single-crystal X-ray analysis of (tri-methylsilyl)cyclopropenes 6 and 7 and these two (trimethylsilyl)cyclopropenes can be converted into cyclopropenes 8 and 9.…”

“…The regio-and stereochemistry of this ene reaction have been confirmed by single-crystal X-ray analysis of the tetramers formed from [2+2] dimerization of an ene dimer. [11] The regiochemistry of the ene reactions of compound 2 (n = 5) was assigned based on NMR spectroscopic data, but the stereochemistry of these reactions remains unknown. [12] Both of the ene dimers were unstable (n = 5) and isomerized or treated with oxygen at room temperature.…”

The Synthesis and Chemistry of 1,3‐Bridged Polycyclic Cyclopropenes: 8‐Oxatricyclo[3.2.1.02,4]octa‐2,6‐dienes

“…2 Cyclopropenes undergo many unusual processes such as ene dimerization to give 3-cyclopropylcyclopropenes, ring opening reaction to form vinyl carbene, and [2 + 2] cycloaddition to generate tricyclo[3.1.0.0 2,4 ]hexanes in order to release strain energy. 3 Both 1,2-and 1,3-fused bicyclic cyclopropenes, which are more energetic than cyclopropene itself, have been well studied. 3,4 Pioneering work in highly strained cyclopropenes with various polycyclic frameworks done by Szeimies has led to some important studies of dehydroquadricyclane (1), 5 tetracyclo[4.1.0.0 2,4 .0 3,5 ]hept-3-ene (2), 6 tricyclo[3.1.0.0 2,6 ]hex-1(6)-ene (3), 6 and tricyclo[4.1.0.0 2,7 ]-hept-1(7)-ene (4).…”