1-Heptanethiol → 2,7-Dibromo-9-(bis-heptylsulfanyl-methylene)fluorene

Participants

Reaction Steps

A 60% dispersion of sodium hydride in mineral oil (3.45 g, 86.25 mmol) was added under a heavy flow of nitrogen to anhydrous toluene (1 L). 1-Heptanethiol (14.65 g, 17.0 mL, 110.7 mmol) was added via syringe. Once effervescence stopped, 2,7-dibromo-9-dibromomethylene-fluorene (2) (18.50 g, 37.46 mmol) was added followed by 2,2′-bipyridyl (0.29 g, 1.87 mmol) and nickel(II) chloride dimethoxyethane adduct (0.41 g, 1.87 mmol). The reaction was stirred overnight at reflux. After cooling to room temperature, the reaction mixture was washed with 2M aqueous sodium hydroxide (2×100 mL), 5% aqueous hydrochloric acid (2×100 mL), water (200 mL), and brine (200 ml) before being dried over sodium sulphate and evaporated to dryness. Excess 1-heptanethiol was removed via Kugelrohr distillation. The crude product was purified by flash chromatography (eluent: petrol 40-60) followed by recrystallisation from iso-hexane to afford 2,7-dibromo-9-(bis-heptylsulfanyl-methylene)-fluorene (3) (16.76 g, 75%) as a bright yellow solid, purity 100% (GC): υmax (KBr, cm−1) 3068, 2949, 2920, 2851, 1588, 1559, 1513, 1443, 1396, 1330; δH(CDCl3, 300 MHz) 9.09 (2H, s), 7.53 (2H, d, 3JHH=6.0 Hz), 7.43 (2H, d, 3JHH=6.0 Hz), 3.04 (4H, t, 3JHH=7.5 Hz) 1.70 (4H, m), 1.43 (4H, m), 1.26 (12H, m), 0.86 (6H, m); δc(CDCl3, 75 MHz) 145.5, 139.7, 137.6, 136.1, 130.3, 129.5, 121.1, 120.3, 36.4, 31.7, 30.1, 28.9, 22.6, 14.1; M+=596 (t).

Provenance & Evidence