Reaction of 2-bromo-1, 1, 2-trichloro-3, 3-dimethylcyclopropane with one mol. equiv. of methyl lithium at− 90 to 0° C leads to 1, 2-dichloro-3, 3-dimethylcyclopropene. This is stable for several hours at 20° C in chloroform or benzene solution but in the presence of an electron-rich or electron-poor alkene reacts in 15 m to 2 h under these conditions to give products apparently derived by reaction of these with 1, 2-dichloro-3-methylbut-2-en-1- ...
