“…First, this author has studied the cycloaddition of substituted allenes with 1,1-dichloro-2,2-difluoroethene as a model for the two-step diradical-intermediate [2+2] cycloaddition of allenes. 24 Thus, the stereoselectivities, chemoselectivities, relative reactivities and kinetic isotope effects in the cycloaddition reaction of substituted allenes with 1,1-dichloro-2,2-difluoroethene, have been determined by comparison with the radicalchain addition of benzenethiol to substituted allenes. 25 The cycloaddition reaction of 1,1-di-and monosubstituted allenes 10a-f with 1,1-dichloro-2,2-difluoroethene has been carried out at 160 1C in a sealed tube affording mixtures of the adducts 11-14 (Scheme 8).…”