Reaction Steps
4-Methylbenzenesulfonyl chloride (5.7 g, 30 mmol), 4-pentyn-1-ol (1.8 mL, 20 mmol) and pyridine (3.2 mL, 40 mmol) in CH2Cl2 (20 mL) were treated according to Procedure 4 giving pent-4-ynyl 4-methylbenzenesulfonate (4.60 g, 97%) as a colourless oil. Vanillin (0.98 g, 6.4 mmol) was alkylated with pent-4-ynyl 4-methylbenzenesulfonate (2.3 g, 8.3 mmol) according to Procedure 4 and the crude product was recystallised from EtOAc/petrol to provide 3-methoxy-4-(pent-4-ynyloxy)benzaldehyde (1.25 g, 89%) as a colourless crystalline solid; mp 91-92° C.; δH (400 MHz, CDCl3) 1.98 (t, J=2.8 Hz, 1H, C≡CH), 2.09 (p, J=7.0 Hz, 2H, CH2), 2.43 (td, J=7.0, 2.8 Hz, 2H, CH2C≡CH), 3.91 (s, 3H, OCH3), 4.21 (t, J=7.0 Hz, 2H, OCH2), 6.99 (d, J5,6=8.0 Hz, 1H, H5), 7.40 (s, 1H, H2), 7.43 (d, J5,6=8.0 Hz, 1H, H6), 9.84 (s, 1H, CHO); δC (100 MHz, CDCl3) 15.1, 27.8, 56.0, 67.3, 69.1, 83.1, 109.3, 111.5, 126.7, 130.1, 149.9, 153.9, 190.8; vmax 1028, 1265, 1583, 1674, 2956, 3214 cm−1.
