Structural Motifs of Alkali Metal Superbases in Non-coordinating Solvents

Lochmann-Schlosser superbases (LSB) are a standard reagent in synthetic chemistry to achieve an exchange of a proton on an organic framework with an alkali metal cation, which in turn can be replaced by a wide range of electrophilic groups. In standard examples, the deprotonating reagent consists of an equimolar mixture of n-butyllithium and potassium t-butoxide. However, the nature of the reactive species could not be pinned down either for this composition or for similar mixtures with comparable high reactivity. Despite the poor solubility and the fierce reactivity, some insights into this mixture were achieved by some indirect results, comparison with chemically related systems, or skillful deductions. Recent results, mainly based on new soluble compounds, delivered structural evidence. These new insights lead to advanced and more detailed conclusions about the interplay of the involved components.

Automated summary

Lochmann-Schlosser superbases (LSB) are standard reagents in synthetic chemistry for exchanging protons on organic frameworks with alkali metal cations, which can then be replaced by various electrophilic groups. Recent research, mainly based on new soluble compounds, has provided structural evidence for the nature of the reactive species in LSB mixtures, leading to advanced and detailed conclusions about the interplay of the components involved.