Mesityllithium has proven to be an effective iodine-lithiumexchange reagent. Thus, carbolithiation reactions on 2-alkenyl-substituted N-( O-iodobenzyl)pyrroleshave been accomplished avoiding side reactions to afford pyrroloisoquinolinesin high yields (80-92%), improving the resultsobtained with T-BuLi. The carbolithiationreaction requires the use of electron-deficient alkenes. Mesityllithiumhas also