Importance of the Halogen in the Competition Between Metal Halogen Exchange and 1,3-Elimination of 1-Halobicyclo(1.1.1)pentane

1-Iodobicyclo[1.1.1]pentane reacts cleanly with t-butyllithium by a metal-halogen exchange process to give 1-lithiobicyclo[1.1.1]pentane. Both 1-chlorobicyclo[1.1.1]pentane and the parent hydrocarbon bicyclo [1.1.1]pentane are found to be inert to t-butyllithium.