Tuning Reactivities of tert‐Butyllithium by the Addition of Stoichiometric Amounts of Tetrahydrofuran

Abstract

In alkyllithium chemistry the highest reactivity has historically been linked to the smallest degree of aggregation possible. Since tert‐butyllithium is known to form a monomer in tetrahydrofuran solution, using just stoichiometric amounts of the lewis base to selectively form a dimeric species seemed irrational. In this study, we showed a considerable increase of the reactivity of t‐BuLi when using stoichiometric amounts of THF in the non‐polar solvent n‐pentane in order to enable the deprotonation of simple methyl silanes and other low C–H‐acidic substrates. In this context, we were able to obtain the corresponding aggregates of t‐BuLi with the ligand THF in suspension and as crystalline solids and investigate them by single crystal X‐ray structural analysis, in situ FTIR spectroscopy and quantum chemical calculations. Furthermore, we were able to explain the enhanced reactivity of t‐BuLi with stoichiometric amounts of THF on the basis of structural features of the bridged dimer obtained under these conditions. With these findings, we present a new target in the aggregation of alkyllithium reagents: the selectively formed “frustrated” aggregates!

Anionic polymerization of phenyl-substituted isoprene derivatives: polymerization behaviour and cyclization-enabled fluorescence

“…Strohmann et al reported experiments with tert -butyl lithium and THF in a ratio of 1 : 2, revealing remarkable aggregation, leading to an increase in reactivity compared to the ratios 1 : 1 and 1 : 2.5. 45 Consequently, the polymerization rate is enhanced by small amounts of THF, promoting the formation of vinylic units. The faster kinetics may also explain the broad distribution observed for entry 12.…”