Acetic Acid → 10-(4-Methylnaphth-1-yl)anthracene-9-boronic acid pinacol ester

Participants

Reaction Conditions

Reaction Steps

44.0 ml (110 mmol) of n-butyllithium (2.5M in n-hexane) are added over the course of 20 min. to a vigorously stirred suspension, cooled to −78° C., of 39.7 g (100 mmol) of 9-bromo-10-(4-methylnaphth-1-yl)anthracene in 1000 ml of diethyl ether, and the mixture is subsequently stirred at −78° C. for 30 min. The suspension is allowed to warm to 20° C. over the course of 2 h, is stirred at 20° C. for a further 2 h and re-cooled to −78° C. 28.0 ml (250 mol) of trimethyl borate are added over the course of 5 min. with vigorous stirring, and the suspension is allowed to re-warm to 20° C. After 15 h at 20° C., a mixture of 15.0 ml (250 mol) of acetic acid in 200 ml of water is added, and the mixture is stirred at room temperature for a further 5 h. After the water phase has been separated off, the organic phase is evaporated to dryness under reduced pressure. 300 ml of n-hexane are added to the slurry which remains, and the mixture is stirred vigorously for 1 h. The solid formed is subsequently filtered off with suction, washed twice with 100 ml of n-hexane and sucked dry. The solid is suspended in 150 ml of toluene, 13.0 g (110 mmol) of pinacol are added, and the mixture is boiled on a water separator for 5 h. The crystals deposited after cooling of the toluene solution are filtered off with suction, recrystallised twice from DMSO and subsequently sublimed (T=350° C., p=5×10−5 mbar); yield: 30.4 g (68.4% of theory), 99.9% according to 1H-NMR.

Provenance & Evidence