Reaction Steps
4-Methylbenzenesulfonyl chloride (5.7 g, 30 mmol), 3-butyn-1-ol (1.5 mL, 20 mmol) and pyridine (3.2 mL, 40 mmol) in CH2Cl2 (20 mL) were treated according to Procedure 4 giving but-3-ynyl 4-methylbenzenesulfonate (4.15 g, 93%) as a colourless oil. Vanillin (0.86 g, 5.7 mmol) was alkylated with but-3-ynyl 4-methylbenzenesulfonate (1.9 g, 8.5 mmol) according to Procedure 4 and the crude product was recystallised from EtOAc/petrol to provide 4-(but-3-ynyloxy)-3-methoxybenzaldehyde (0.39 g, 34%) as a colourless crystalline solid; mp 101-102° C.; δH (400 MHz, CDCl3) 2.07 (t, J=2.8 Hz, 1H, C≡CH), 2.79 (td, J=7.2, 2.8 Hz, 2H, CH2C≡CH), 3.93 (s, 3H, OCH3), 4.25 (t, J=7.2 Hz, 2H, OCH2), 7.00 (d, J5,6=8.0 Hz, 1H, H5), 7.42 (d, J2,6=2.0 Hz, 1H, H2), 7.45 (dd, J5,6=8.0, J2,6=2.0 Hz, 1H, H6), 9.86 (s, 1H, CHO); δC (100 MHz, CDCl3) 13.3, 56.1, 67.0, 70.5, 79.6, 109.6, 112.0, 126.6, 130.5, 149.9, 153.3, 190.9; vmax 1021, 1269, 1586, 1677, 2940, 3246 cm−1.
