Chlorodiisopropylphosphine → 4,7-Dimethoxy-1,2,3-trimethylindenyl-diisopropyl-phosphonium trifluoroborate

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Reaction Conditions

Reaction Steps

In a 100 ml Schlenk flask 4,7-dimethoxy-1,2,3-trimethylindene (39) (1.7 g, 7.79 mmol) was dissolved in Et2O (50 ml) under an argon atmosphere. The mixture was cooled to −60° C. (N2/isopropanol) and n-BuLi (3 ml, 2.5 M solution in hexane, 7.43 mmol) was added. The solution was stirred for 10 min at −60° C., then for 3 hours at ambient temperature. A white precipitate was formed. Then the mixture was cooled to −60° C. and iPr2PCl (1 ml, 6.24 mmol) was added. The mixture was allowed to come to room temperature, stirred for additional 2 h at ambient temperature and the formed LiCl was removed by filtration over a pad of Celite® under Schlenk conditions. The resulting slightly yellowish filtrate was treated dropwise with HBF4-Et2O (1 ml, 7.72 mmol) to give a white precipitate which was separated via filtration and dissolved in 10 ml chloroform. After filtration the clear filtrate was dropped into Et2O (700 ml, vigorously stirred). The formed white precipitate was separated via suction filtration. Removal of the volatiles in vacuo afforded (21a) as a white solid (1.73 g, 66%).

Provenance & Evidence