1,3-dibromo-5-ethenylbenzene

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Tetrahydrofuran (20 mL) was added to methyltriphenylphosphonium bromide (3.150 g, 8.8 mmol). Then potassium t-butoxide (0.989 g, 8.8 mmol) was added herein small portions with ice-cooling, and the mixture was stirred at room temperature for 1 hr. The resultant slurry was cooled to −78° C. and a tetrahydrofuran (20 mL) solution containing 3,5-dibromobenzaldehyde (1.519 g, 5.8 mmol) was added dropwise. The reaction solution was allowed to warm to room temperature and stirred for 1 hr, and then a saturated ammonium chloride aqueous solution was added to the reaction solution. The product was extracted with ethyl acetate, the solvent was distilled off under reduced pressure, and the residue was purified with silica-gel column chromatography to obtain 3,5-dibromostyrene (1.2 g, 4.6 mmol). cooling The resultant slurry was cooled to −78° C. was added dropwise to warm to room temperature stirred for 1 hr The product was extracted with ethyl acetate the solvent was distilled off under reduced pressure the residue was purified with silica-gel column chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 1,3-dibromo-5-vinyl-benzene (4.55 g, 17.4 mmol) and 20% Pd(OH)2/C (2.0 g) in THF (60 mL) is purged with N2 and then H2, and the mixture is stirred under a H2 balloon at rt for 5 hours. The mixture is filtered through hyflo, and the solvent is removed in vacuo to afford crude product that is absorbed on silica gel and purified by flash chromatography using 15/1 hexanes/ethyl acetate to afford 3.38 g (74%) of the title compound. Rf=0.63 (9/1 hexanes/EtOAc). 1H NMR (400 MHz, CDCl3). is purged with N2 The mixture is filtered through hyflo the solvent is removed in vacuo to afford crude product that is absorbed on silica gel purified by flash chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of methyltriphenylphosphonium bromide (20.30 g, 56.8 mmol) in dry THF (50 mL) is cooled to 0° C. under N2 and then treated with solid potassium tert-butoxide (6.38 g, 56.8 mmol) in portions. The resultant yellow slurry is warmed to rt and stirred for 30 minutes. The mixture is cooled to −78° C., and a solution of 3,5-dibromobenzaldehyde (10.0 g, 37.9 mmol) in THF (50 mL) is added dropwise. The reaction is warmed to rt and stirred for 1 hour. The mixture is poured into ice water containing 1 N HCl (56 mL) and then extracted with Et2O. The organic layer is dried (Na2SO4), and the solvent is removed in vacuo to afford crude product that is absorbed on silica gel and purified by flash chromatography using 10/1 hexanes/ethyl acetate to afford 4.56 g (46%) of the title compound. Rf=0.64 (4/1 hexanes/EtOAc). 1H NMR (400 MHz, CDCl3). The mixture is cooled to −78° C. The reaction is warmed to rt stirred for 1 hour extracted with Et2O The organic layer is dried (Na2SO4) the solvent is removed in vacuo to afford crude product that is absorbed on silica gel purified by flash chromatography