Iodine → 2-{4-[6-(Tert-butyl-dimethylsilanyloxy)hexyl]-phenyl}-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane

Participants

Reaction Conditions

Reaction Steps

To a suspension of zinc powder (5.0 g, 76.46 mmol) in anhydrous DMA (30 ml) is added iodine (0.5 g, 2 mmol). This mixture is stirred until the red color of I2 disappeared (ca. 2 min), followed by the addition of (6-bromohexyloxy)-tert-butyl-dimethylsilane (15.0 g, 50.79 mmol) and the mixture is stirred at 85° C. for 4.5 h, then cooled to room temperature and excess zinc allowed to settle. In another flask charged with anhydrous THF (30 ml) is added 2-(4-iodophenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (15.0 g, 45.46 mmol) and Pd(dppf)Cl2 (0.85 g, 0.10 mmol). This mixture is stirred for 10 min, then the solution of organozinc reagent is transferred by cannula into the flask. The reaction mixture is stirred overnight (˜16 h) at room temperature. Sat. aq. NH4Cl solution is added and the mixture is extracted with ethyl acetate (3×70 ml). The extracts are dried (Na2SO4) and evaporated under reduced pressure. The residue is purified by column chromatography, eluting with petrol/ethyl acetate (10:0 to 4:1), to give a brown oil (13.83 g, 73%). 1H NMR (300 MHz, CDCl3): δ(ppm) 7.70 (d, J=7.9 Hz, 2H, Ar—H), 7.14 (d, J=7.9 Hz, 2H, Ar—H), 3.54 (t, J=6.6 Hz, 2H, OCH2), 2.56 (t, J=7.3 Hz, 2H, ArCH2), 1.27-1.65 (m, 20H, CH2 and CH3), 0.85 (s, 9H, CH3), 0.05 (s, 6H, CH3); 13C NMR (75 MHz, CDCl3): δ(ppm) 146.3 (quat.), 134.9 (CH), 127.9 (CH), 83.6 (2×quat.), 63.3 (CH2), 36.2 (CH2), 32.9 (CH2), 31.4 (CH2), 29.1 (CH2), 26.1 (3×CH3), 25.8 (CH2), 24.9 (4×CH3), 18.4 (quat.), −5.2 (2×CH3).

Provenance & Evidence