Synthesis of alkoxy- and phenylsulfanyl-substituted 1,1-dihalospiro[2.2]pentanes and their reactivity toward methyllithium

A number of new alkoxy- and phenylsulfanyl-substituted 1,1-dihalospiro[2.2]pentanes bearing different halogen atoms were synthesized. 1,1-Dihalo-4- tert -butoxyspiro[2.2]pentanes reacted with methyllithium at −55 to −10°C to give exclusively 1- tert -butoxy-2-vinylidenecyclopropane. The reaction of 1-bromo-1-fluoro-4-phenylsulfanylspiro[2,2]pentane with methyllithium resulted in replacement of the fluorine atom by methyl group.