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0 °C

38.2 g (265 mmol) of 4,7-dimethylindene was dissolved in 350 ml of tetrahydrofuran and the solution was cooled to 0° C. Then 165 ml of n-butyllithium (1,6M in hexane, 264 mmol) was added dropwise over 2.5 hours. After warming to room temperature and stirring for 4 hours a purple solution of 4,7-dimethylindenyl-lithium was obtained. This solution was cooled to -70° C. and treated dropwise with 25,3 g of 1,2-dibromoethane (135 mmol) in 15 ml of tetrahydrofuran over 35 min. After warming to room temperature, a pale yellow solution was obtained, and then water was added. The organic phase was collected and dried over Na2SO4. The solvent was removed by vacuum evaporation to provide 20 g of crude product (48% yield).

1. temperatureAfter warming to room temperature
2. customwas obtained
3. temperatureThis solution was cooled to -70° C.
4. temperatureAfter warming to room temperature
5. customa pale yellow solution was obtained
6. customThe organic phase was collected
7. dry with materialdried over Na2SO4
8. customThe solvent was removed by vacuum evaporation