Thermal Izomerizations of cis- and trans-2,2-Difluoro-3-methyl-1-vinylcyclopropane

Article abstract of DOI:10.1021/jo00340a001

The thermal isomerizations of cis- and trans-2,2-difluoro-3-methyl-1-vinylcyclopropane (4 and 5) proceed in a manner reminiscent of the respective hydrocarbon systems. 3,3-Difluoro-1,4-hexadiene (8) is the sole product from 4 while 3,3-difluoro-4-methylcyclopentene (9) is the major product from 5.Both 4, in undergoing its concerted H-shift process, and 5, in rearranging via a diradical process, exhibit the 8-10 kcal/mol incremental activation energy lowering which is expected for reactions involving cleavage of that cyclopropane carbon-carbon bond which is opposite the gem-difluoro substituent.