Synthesis and Chemistry of Bicyclo[4.1.0]hept-1,6-ene.
Bicyclo[4.1.0]hept-1,6-ene has been generated by elimination of 1-chloro-2-(trimethysilyl)bicyclo[4.1.0]heptane in the gas phase over solid fluoride at 25 degrees C. The cyclopropene dimerizes by a rapid ene reaction forming two diastereomeric cyclopropenes. In tetrahydrofuran or chloroform the ene dimers couple to form a single crystalline triene tetramer, whereas a mixture of tricyclohexane tetramers is formed when the neat dimers are allowed to warm to room temperature. Oxidation by dimethyldioxirane or dioxygen gives carbonyl products. Quantum mechanical calculations yielded an increase in strain of approximately 17 kcal/mol over that for 1,2-dimethylcyclopropene. The potential enegy barrier to flexing (folding) along the fused double bond of bicyclo[4.1.0]hept-1,6-ene is only approximately 1 kcal/mol at the highest level of theory investigated.
Billups
W. E.
WE
Department of Chemistry, Yale University, New Haven, Connecticut 06520.
Luo
Weimei
W
Lee
Gon-Ann
GA
Chee
Jennifer
J
Arney
Benny E.
BE
Wiberg
K. B.
KB
Artis
Dean R.
DR