Halogen–Sodium Exchange Revisited
Sodium is the most abundant alkali metal on Earth. Despite being an attractive choice for sustainable synthesis, organosodium compounds are rarely used in organic synthesis and have been overshadowed to date by organolithium compounds. This situation is largely due to the lack of convenient and efficient methods for the preparation of organosodium compounds. We report herein a halogen–sodium exchange method to prepare a large variety of (hetero)aryl- and alkenylsodium compounds, many of them previously inaccessible by other methods. The key discovery is the use of a bulky alkylsodium lacking a β-hydrogen, readily prepared in situ from neopentyl chloride and an easy-to-handle sodium dispersion, which retards undesired reactions such as Wurtz–Fittig coupling and β-hydrogen elimination, and enables efficient halogen-sodium exchange. We believe that the efficiency, generality, and convenience of the present method will open new horizons for the use of organosodium in organic synthesis, ultimately contributing to the development of sustainable chemistry by replacing the currently dominant organolithium reagents.