Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen-lanthanum exchange with nBu LaMe, which leads to functionalized diaryl- and diheteroaryllanthanum derivatives. Subsequent trapping reactions with selected electrophiles, such as ketones, aldehydes, or amides, proceeded smoothly at -50 °C in THF, affording polyfunctionalized alcohols and carbonyl derivatives. Kinetic competition experiments revealed a similar reactivity trend as for Br/Mg exchange, but 10 -times higher rates, making it comparable to Br/Li exchange.
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