While the original procedures described for the title reagent (1) employed a stoichiometric amount of t-Butyllithium in a minimum quantity of THF at low temperature, it since has been reported that the deprotonation reaction takes place with mixtures of n-Butyllithium and N,N,N′,N′-Tetramethylethylenediamine in hexane at 0 °C3 or n-BuLi in ether at 0 °C. A representative procedure consists of the addition of 0.8 equivalent of t-BuLi (1.8 M in pentane) to a THF solution of freshly distilled 2,3-dihydrofuran at -40 °C for 0.5 to 1 h. An alternative deprotonation method uses a 1:1:1 mixture of n-BuLi, Potassium t-Butoxide, and TMEDA in hexane for 15 min at -30 °C. (1) can be used in THF solution or in ether after evaporation of the original solvents. The THF solution is stable for at least a few hours at room temperature. However, lithiodihydrofuran in THF partly decomposes after 24 h at 25 °C into lithium alkynolate and ethylene. This reaction in the presence of excess base and silylating reagent leads to bis(silyl)ketenes (eq 1).
