162607-19-4

180 g (728 mmol) of 1-bromodibenzofuran aredissolved in 1500 ml of dry THF and cooled to -78?? C. 305 ml (764 mmol/2.5 M in hexane) of n-butyllithium are added at this temperature over the course of about 5 min., and the mixture is subsequently stirred at -78?? C. for a further 2.5 h. 151 g (1456 mmol) of trimethyl borate are added as rapidly as possible at this temperature, and the reaction mixture is allowed to come slowly to room temperature (about 18 h). The reaction solution is washed with water, and the precipitated solid and the organic phase are dried azeo- tropically with toluene. The crude product is washed by stirring with toluene/methylene chloride at about 40?? C. and filtered off with suction. Yield: 146 g (690 mmol), 95% of theory.