Br[C:2]1[C:15]2[CH:16]=[CH:17][CH:18]=[CH:19][C:14]=2[C:13]2[C:12]3[CH:11]=[CH:10][CH:9]=[CH:8][C:7]=3[CH:6]=[CH:5][C:4]=2[CH:3]=1.C([Li])CCC.[B:25](OC(C)C)([O:30]C(C)C)[O:26]C(C)C.Cl>CCCCCC.CCOCC>[CH:19]1[C:14]2[C:13]3[C:12]4[CH:11]=[CH:10][CH:9]=[CH:8][C:7]=4[CH:6]=[CH:5][C:4]=3[CH:3]=[C:2]([B:25]([OH:30])[OH:26])[C:15]=2[CH:16]=[CH:17][CH:18]=1
Under the atmosphere of argon, 10.1 g of 5-bromobenzo[c]phenanthrene was placed in a flask, and 400 mL of dehydrated ether was added. The reaction solution was cooled to −40° C., and 22 mL of a hexane solution of 1.6 M n-butyl lithium was added. The resultant was heated to 0° C., and stirred for 1 hour. The reaction solution was cooled to −60° C., and 10 mL of a dehydrated ether solution of 14.4 g of triisopropyl borate was added dropwise. While heating the reaction solution to room temperature, stirring was continued for 5 hours. 10 mL of a 10% aqueous hydrochloric acid solution was added, followed by stirring for 1 hour. An aqueous phase was removed, and an organic phase was washed with water and saturated saline, and dried with magnesium sulfate. After filtering off magnesium sulfate, the organic phase was concentrated. The resulting solids were washed with hexane, whereby 5.37 g (yield 60%) of benzo[c]phenanthrene-5-boronic acid as an intended product was obtained.
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