106988-83-4Relevant articles and documents
7-Arylbicyclooct-1-enes - Synthesis by Cycloadditions of 1,2-Cyclohexadiene and 1-Methyl-1,2-cyclohexadiene and Thermal Equilibration of the exo/endo Isomers
Christl, Manfred,Schreck, Michael
, p. 915 - 920 (2007/10/02)
The exo/endo ratio of the isomers 3a, b formed in the known cycloaddition of styrene to 1,2-cyclohexadiene (2) has been found to depend on the temperature.The ultilization of (Z)-deuteriostyrene provided the proof of the stepwise nature of this reaction with the diradical 4 as the most probable intermediate.Heating of 3b at 140-170 deg C established the thermodynamic equilibrium between 3a and 3b (3a:3b = 93:7) and again 4 is assumed to be the intermediate.By means of kinetic measurements the activation parameters of the system 3a 3b have been determined. - From 2 and the trapping reagents p-methoxy-styrene, 1,1-diphenylethylene, and 1-phenylpropene the title compounds 6a, b, 7, and 8, respectively, were formed in low yields.In analogy to 2 its 1-methyl derivative 13 has been generated from 6,6-dibromo-1-methylbicyclohexane (9) with methyllithium.From the reaction in the presence of styrene the trapping products 14a, b were isolated in addition to the dimer 12 or 13. - The 1H NMR spectra of the title compounds support a rigid halfchair conformation of the cyclohexene moiety with the cyclobutane ring anellated equatorially.
