title: Thermal chemistry of bicyclo[4.2.0]oct-2-enes.
abstract: At 300 degrees C, bicyclo[4.2.0]oct-2-ene (1) isomerizes to bicyclo[2.2.2]oct-2-ene (2) via a formal [1,3] sigmatropic carbon migration. Deuterium labels at C7 and C8 were employed to probe for two-centered stereomutation resulting from C1-C6 cleavage and for one-centered stereomutation resulting from C1-C8 cleavage, respectively. In addition, deuterium labeling allowed for the elucidation of the stereochemical preference of the [1,3] migration of 1 to 2. The two possible [1,3] carbon shift outcomes reflect a slight preference for migration with inversion rather than retention of stereochemistry; the si/sr product ratio is approximately 1.4. One-centered stereomutation is the dominant process in the thermal manifold of 1, with lesser amounts of fragmentation and [1,3] carbon migration processes being observed. All of these observations are consistent with a long-lived, conformationally promiscuous diradical intermediate.
authors.affiliation: Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Powers
authors.forename: Phyllis A
authors.initials: PA
authors.lastname: Leber
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Gallagher
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Higgs
authors.forename: Lynne A
authors.initials: LA
authors.lastname: McCullough
authors.forename: John E
authors.initials: JE
authors.lastname: Baldwin