The thermal cis–trans-isomerization of some substituted tetraphenyl-cyclopropanes. An assessment of the importance of merostabilization of a 1,3-biradical

Abstract

The Arrhenius kinetic parameters for the thermal cis–trans-isomerization of 1,2-di-(p-methoxyphenyl)-1,2-diphenyl-(1a), 1,2-di-(p-cyanophenyl)-1,2-diphenyl-(1b), 1-(p-cyanophenyl)-2-(p-methoxyphenyl)-1,2-diphenyl-(1c), and 1,2-di-(p-methoxyphenyl)-1,2-di-(p-methoxyphenyl)-cyclopropane (1d) give an indication of the substituent effects on the stability of the transient 1,3-biradical.