Halogen−Metal Exchange in 1,2-Dibromobenzene and the Possible Intermediacy of 1,2-Dilithiobenzene

The one-step high-yield synthesis of 1,2-bis(trimethylsilyl)benzene from 1,2-dibromobenzene using tert-butyllithium and trimethylsilyltriflate is reported. A mechanistic investigation shows that 1,2-dilithiobenzene is not an intermediate in this reaction; the coexistence of trimethylsilyltriflate and tert-butyllithium at very low temperatures allows a sequence of bromine-lithium exchange and subsequent derivatization reactions to operate.