Thermal rearrangement of substituted difluoro(methylene)cyclopropane

Progress in the Synthesis and Transformations of Alkylidenecyclopropanes and Alkylidenecyclobutanes

“…Compounds 21 can be subsequently modified to produce new ACPs through known procedures such as the Heck reaction or reaction with electrophiles after lithiation of the double bond . The thermal isomerization of compound 21 (R 1 , R 2 = Me) affords two new difluorinated MCP derivatives 22 and 23 (Scheme ) …”

“…This concept has been used in the isomerization of difluoroalkylidenecyclopropane 21 , (see Scheme , section ), taking advantage of the relatively mild conditions required for the rearrangement as a consequence of the difluorosubstitution …”

The preparation and properties of 1,1-difluorocyclopropane derivatives

“…It was also observed that the equilibrium lay significantly in favor of the rearranged product 97, which was by 1.9 kcal/mol more stable. The thermal ring opening of the tosyl-substituted 1,1-difluoro-2,2-dimethyl-3-methylenecyclopropane 98 led to the thermodynamically more stable products 99 and 100, respectively (Scheme 46) [93].…”