The first example of 2,2-dilithiocyanocyclopropanes: generation from 2-bromo-2-sulfinylcyanocyclopropanes with tert-butyllithium, property, and a synthesis of fully substituted cyanocyclopropanes

2,2-Dilithiocyanocyclopropanes were easily generated from 2-bromo-2-(p-tolylsulfinyl)cyanocyclopropanes with tert-butyllithium in toluene at −78 °C through concomitant sulfoxide–lithium and bromine–lithium exchange reactions. The gem-dianions were found to be stable at −78 °C for at least 30 min. Reaction of the gem-dianions with electrophiles gave fully substituted cyanocyclopropanes in moderate yields.