Ab Initio Calculations on the Stereomutation of 1,1-Difluorocyclopropane. Prediction of a Substantial Preference for Coupled Disrotation of the Methylene Groups

Structure, Synthesis, and Chemical Reactions of Fluorinated Cyclopropanes and Cyclopropenes

“…93,94 In contrast, ab initio calculations by Getty, Hrovat, and Borden predicted a very different behavior for the stereomutations of gem-difluorocyclopropanes. 22, 35 1,1-Difluorocyclopropane is predicted to show a large preference for stereomutation by disrotation of C(2) and C(3). Such preference is predicted to be enhanced, not diminished, by alkyl substituents.…”

“…104 Such preference was consistent with Borden's later estimates of a difference of 3.9 kcal/mol between the (0,0)-conformation of 2,2-difluorotrimethylene and the (0,90)-conformation of the 1,1-difluorotrimethylene diradical. 35 An interesting fluorinated divinylcyclopropane system, 17, has been examined kinetically. The E a for its rearrangement to 18 is 9 kcal/mol lower than the rearrangement of an analogous non-fluorine-substituted compound.…”

Competitive kinetic processes in the thermal rearrangement of 1,1-difluoro-2-(dideuteriomethylene)-cyclopropane

“…Therefore, the observed smaller kinetic effect of the fluorine substituents in the methylenecyclopropane system remained an issue of concern. This issue along with others related to the impact of geminal fluorine substituents on the structure and energy of cyclopropane and those intermediates and transition states on its thermal energy surface were initially addressed by Getty et al [4,5].…”

Is π-Single Bonding (C–π–C) Possible? A Challenge in Organic Chemistry

“…¹9 kcal mol ¹1 ), 15 Table 1. Later in 1998, the singlet ground state of 2,2-difluorocyclopropane-1,3-diyl was experimentally confirmed by generating the short-lived CP2 (X = F, 293 = ca.…”