Metallation of Indene

Subsequent reactions with n-butyl bromide and trimethylchlorosilane. 

Apparatus p. 24, 500 ml, the dropping funnel is replaced by a rubber septum 

Indene (O.lOmol, 11.6g) and THF (70ml) are placed in the flask. The solution is cooled to — 40 °C and a solution of O.lOmol of butyllithium in 67 ml of hexane is added over a few min from a syringe. The cooling bath is removed and the orange solution can immediately be used for derivatization reactions. 

A mixture of 0.20 mol (27.4 g, 100% excess) of butyl bromide and 50 ml of THF is placed in the flask. The solution of indenyllithium is added over 10 min (by means of a syringe) to this mixture, while keeping the temperature between — 40 and — 20 °C. After an additional 15 min the cooling bath is removed and the temperature allowed to rise to 0 °C. Water (100 ml) is then added after which the aqueous layer is extracted 

A similar procedure is followed for the reaction of indenyllithium with trimethylchlorosilane (a 100% molar excess of Me3SiCl is used). 1-(Trimethylsilyl)indene, b.p. 105 °C/12 mmHg, nD(20) 1.5422, is obtained in 70% by careful fractional distillation. The small fraction with b.p. 106-115 °C/12 mmHg contains 2Q% of 3-(trimethylsilyl)indene and some of a bis(trimethylsilyl) derivative. 

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