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0 °C

38.2 g (265 mmol) of 4,7-dimethylindene were dissolved in 350 ml of tetrahydrofuran and the temperature of the solution was cooled to 0° C. Then, 165 ml of n-butyllithium (1.6M in hexane, 264 mmol) were added, dropwise for 2.5 hours. After having again heated up to room temperature and stirred the whole for 4 hours, a purple-red solution of 4,7-dimethylindenyl-lithium was obtained. This solution was cooled to -70° C. and treated, dropwise for 35 minutes, with 25.3 g of 1,2-dibromoethane (135 mmol) in 15 ml of tetrahydrofuran. After having heated up to room temperature, a slight yellow solution was obtained to which water was added. The organic phase was collected ed dried on Na2SO4. The solvent was then evaporated under vacuum and 20 g of product were obtained (yield 48%).

1. temperatureAfter having again heated up to room temperature