Thermal Isomerization of cis,anti,cis-Tricyclo[6.3.0.0^2,7]undec-3-ene to endo-Tricyclo[5.2.2.0^2,6]undec-8-ene

Abstract

[reaction: see text] The gas-phase thermal isomerization of cis,anti,cis-tricyclo[6.3.0.0(2,7)]undec-3-ene (1) to endo-tricyclo[5.2.2.0(2,6)]undec-8-ene (2) at 315 degrees C occurs cleanly through a symmetry-forbidden [1,3] suprafacial,retention (sr) pathway.

Reaction mechanisms : Part (ii) Pericyclic reactions

“…Baldwin and co-workers investigated the related [1,3] alkyl shift of cis,anti,cistricyclo[6.3.0.0 2,7 ]undec-3-ene (Scheme 15), 27 demonstrating that this rearrangement produces an orbital symmetry forbidden sr product exclusively; a stepwise mechanism with a short-lived, geometrically constrained diradical was again proposed. Houk, Hassellman and co-workers examined the the [1,3] sigmatropic shift of 6-methylenebicyclo[3.2.0]hept-2-ene (Scheme 16) using thermolysis experiments with isotopically labeled reactants and B3LYP, CASSCF and CASPT2 calculations.…”