Hydrogen Bromide → 3,9-Dibromo-5,7-dihydrodibenzo[c,e]oxepine
Reaction equation
[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH:13]=[CH:12][C:11]([Br:14])=[CH:10][C:9]=2[CH2:15]O)=[C:4]([CH2:17][OH:18])[CH:3]=1.Br>C1COCC1>[Br:14][C:11]1[CH:12]=[CH:13][C:8]2[C:5]3[CH:6]=[CH:7][C:2]([Br:1])=[CH:3][C:4]=3[CH2:17][O:18][CH2:15][C:9]=2[CH:10]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
4,4′-Dibromo-2,2′-bis-hydroxymethyl-biphenyl 23, the structure of which is shown in Scheme 4 above, (5 g, 0.013 moles, prepared according to the procedure described by D. M. Hall, F. Minhaj, J. Chem. Soc., 1957, 4584) was dissolved in THF (50 ml). HBr (48% wt/wt aqueous solution, 40 ml) was added and the solution refluxed overnight. After this period the THF was removed under reduced pressure and the yellow oil extracted between DCM/H2O (DCM is dichloromethane). The combined organic layers were dried (MgSO4), reduced and recrystallised from acetone (100 ml) to yield 3,9-dibromo-5,7-dihydro-dibenz[c,e]oxepin (12) as fine white crystals (1 g). Repeated recrystallisations of the mother liquor gave further product. Total yield after 3 recrystallisations (2.2 g, 0.0062 moles, 48% yield) as fine white crystals.