Thermal [1,3] sigmatropic rearrangements of 2,2-difluoro-1-vinylcyclopropanes

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

“…The lack of regioselectivity observed in our later study of the rearrangement of 1,1-difluoro-2-vinyl-cyclopropane, 3 (Scheme 2) [3] demonstrated that there is, in fact, only a small difference in the energy required for homolytic cleavage of the distal and proximal bonds of the usual gem-difluorocyclopropane. Therefore, the observed smaller kinetic effect of the fluorine substituents in the methylenecyclopropane system remained an issue of concern.…”

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

“…Dolbier and Roth's studies of the thermolyses of the parent, 2,2-difluorovinylcyclopropane, 13, and of 2,2-difluoro-(trans-1-propenyl)cyclopropane, 16, demonstrated a distinct, but far from exclusive, preference for distal bond cleavage, 33,103 this after an initial erroneous report of preferred formation of 15. 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.…”

1,1-Bis(trifluoromethyl)butadiene-1,3—A new fluorinated building block

“…It should pointed out that the introduction of fluorine into cyclopropane rings effectively reduces thermal stability of vinyl cyclopropanes [17][18][19]. This is the reason why the addition of difluorocarbene at elevated temperature to CF 2 CFCF CF 2 [20], CF 2 CFCCl CF 2 and CF 3 CF CFCF CF 2 [21] results in high yield formation of the corresponding fluorinated cyclopentenes, since thermally less stable vinylcyclopropanes undergo isomerization under the reaction conditions [19,20].…”

“…Quadricyclane (18) was prepared by photochemical isomerization of norbornadiene [35] using tbutyl methyl ether as a solvent. Compound 1 was prepared according literature procedure [4].…”