Homolytic displacements at carbon. Part 8. Synthesis of 1-cyano-2-(trichloroethyl)cyclopropanes from allylcobaloximes via but-3-enylcobaloximes and 1-bromo-1-cyanobut-3-enes

Several 1-cyano-2-(trichloroethyl)cyclopropanes have been synthesised by a sequence of reactions involving homolytic displacement of cobaloxime(II) from allylcobaloxime(III) complexes by bromocyanomethyl radicals and homolytic displacement of cobaloxime(II) from but-3-enylcobaloxime(III) complexes by trichloromethyl radicals : the latter complexes being formed from the 1-bromo-1-cyanobut-3-enes formed in the reactions of the allylcobaloxime(III) complexes. In cases where the but-3-enylcobaloxime(III) complex could not be synthesised, alternative routes to 1-cyano-2-(trichloroethyl)cyclopropanes have been demonstrated, including the homolytic displacement of bromine atoms from 1-bromo-1-cyanobut-3-enes by trichloromethyl radicals.