Reaction Steps
Nitrogen was bubbled through a solution of 1-(2-Ethylhexyloxy)-4-ethynylbenzene (4) (1.69 g, 7.34 mmol) and 3,5-dibromobenzaldehyde (5) (692 mg, 2.62 mmol) in tetrahydrofuran (33 mL) and triethylamine (50 mL) for 5 min. Tetrakis(triphenylphosphine)palladium(0) (218 mg, 0.189 mmol) and copper(I) iodide (65 mg, 0.34 mmol) were added and nitrogen bubbled through the solution for a further 5 min, before stirring at 70° C. for 23 h. Once cool, the solvent was removed and the residue purified by column chromatography over silica with dichloromethane—light petroleum (1:2 to 1:1) as eluent to leave 3,5-bis[4-(2-ethylhexyloxy)phenylethynyl]benzaldehyde (6) (1.17 g, 79%) as a pale brown oil. (Found: C, 83.3, H, 8.2, C39H46O3 requires C, 83.2; H, 8.2%); νmax(film)/cm−1 2211 (C≡C) and 1704 (C═O); δH(400 MHz, CDCl3) 0.93-0.99 (12 H, m, CH3), 1.28-1.56 (16 H, m, CHCH2CH2CH2CH3 and CHCH2CH3), 1.75 (2 H, m, OCH2CH), 3.87 (4 H, d, J 6 OCH2CH), 6.90 (4 H, AA′BB′), 7.48 (4 H, AA′BB′), 7.87 (1 H, dd, J 1.5, 4-H), 7.92 (2, H, d, J 1.5, 2, 6-H) and 10.00 (1 H, s, CHO); δc(100.6 MHz, CDCl3) 11.1, 14.1, 23.1, 23.8, 29.0, 30.4, 39.3, 70.6, 86.0, 91.7, 114.1, 114.6, 125.2, 131.3, 133.5, 136.6, 139.1, 159.9 and 191.0.
