Preparation of Functionalized Diaryl‐ and Diheteroaryllanthanum Reagents by Fast Halogen–Lanthanum Exchange

Abstract

Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen-lanthanum exchange with nBu₂ 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 10⁶ -times higher rates, making it comparable to Br/Li exchange.