Boron tribromide → HCID 23050232, compound
Reaction equation
C[O:2][C:3]1[C:13]([O:14]C)=[CH:12][C:6]2[S:7][C:8]([C:10]#[N:11])=[CH:9][C:5]=2[CH:4]=1.B(Br)(Br)Br>ClCCl>[OH:2][C:3]1[C:13]([OH:14])=[CH:12][C:6]2[S:7][C:8]([C:10]#[N:11])=[CH:9][C:5]=2[CH:4]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- -70 °C
Procedure
5,6-Dimethoxy-benzo[b]thiophene-2-carbonitrile (9.0 g) was dissolved in dichloromethane (135 ml) and the solution was stirred and cooled to -70° C. and treated at a rapid dropwise rate with a cold solution of boron tribromide (19.5 ml) in dichloromethane (60 ml). The resultant suspension was stirred at room temperature for 1 h. then poured into ice-cold water (1000 ml). The light coloured solid was filtered, dried, dissolved in acetone:hexane (1:1) then eluted through coarse silica (0.2-0.5 mm, Merck, 50 g) in acetone:hexane (1:1). The appropriate fractions were combined, evaporated to dryness and crystallised from acetone/n-hexane to give 5,6-dihydroxy-benzo[b]thiophene-2-carbonitrile (7.5 g), m.p. 229°-230° C.