反応手順
To a suspension of copper bronze (0.646 g, 10 mmol) in anhydrous DMF (2 mL) was added a solution of 2-bromo-3,4,5-trimethoxybenzaldehyde (0.80 g, 2.91 mmol) and 3-bromo-2-formyl-6-methoxyphenyl methanesulfonate (0.30 g, 0.97 mmol) in anhydrous DMF (1 mL) and the suspension was stirred at 165° C. for 3 hours. TLC indicated the presence of unreacted 3-bromo-2-formyl-6-methoxyphenyl methanesulfonate and a further portion of 2-bromo-3,4,5-trimethoxybenzaldehyde (100 mg) was added. After a further 1 hour at 165° C. the reaction was complete and the reaction mixture was cooled and diluted with ethyl acetate (20 mL). The resulting suspension was filtered through Celite® (3 g) and the filtrate concentrated in vacuo. The residue was chromatographed over silica gel (70 g), eluting with hexane-ethyl acetate (gradient 2:1 to 1:1), followed by crystallisation (ethyl acetate) yielded 2,6′-diformyl-4,2′,3′,4′-tetramethoxybiphenyl-3-yl methanesulfonate (180 mg, 44%); m.p. 130-131° C.; Elemental Analysis Found: C, 53.7; H, 4.8; S, 7.8 (C19H20O9S requires C, 53.77; H, 4.75; S, 7.56%); NMR Spectrum δH (300 MHz, CDCl3) 10.18 (1H, s, 2-CHO), 9.63 (1H, s, 6′-CHO), 7.36 (1H, s, 5′-H), 7.26 (1H, d, J 8.4 Hz, 6-H), 7.15 (1H, d, J 8.4 Hz, 5-H), 4.03 (3H, s, OCH3), 3.98 (3H, s, OCH3), 3.57 (3H, s, OCH3), 3.43 (3H, s, SCH3); NMR Spectrum δC (100 MHz, CDCl3) 50.2, 56.5, 56.9, 61.2, 61.5, 106.2, 116.8, 127.5, 130.0, 130.7, 131.0, 132.1, 139.8, 147.6, 151.1, 152.6, 154.0, 189.3, 190.5; νmax/cm−1 (thin film) 2934, 2843, 1701, 1682, 1588, 1561, 1480, 1371, 1336, 1285, 1169, 1111, 1072; m/z (ES) 447 (MNa+, 100%), 379 (5); Rf (hexane-ethyl acetate 1:2) 0.20.
