Vanillin → 3-Methoxy-4-prop-2-ynyloxy-benzaldehyde

Reaction equation

[CH2:1](Br)[C:2]#[CH:3].[O:5]=[CH:6][C:7]1[CH:15]=[CH:14][C:12]([OH:13])=[C:9]([O:10][CH3:11])[CH:8]=1.C(=O)([O-])[O-].[K+].[K+]>CC#N>[CH3:11][O:10][C:9]1[CH:8]=[C:7]([CH:15]=[CH:14][C:12]=1[O:13][CH2:3][C:2]#[CH:1])[CH:6]=[O:5]

Participants

Procedure

Propargyl bromide (293 mL, 80% w/v, 1.97 mol) was added to a suspension of vanillin (250 g, 1.64 mol) and potassium carbonate (681 g, 4.93 mol) in MeCN (2.0 L). The suspension was heated to reflux for 6 h and the solvent was removed under reduced pressure. Water was added and the aqueous phase was extracted with EtOAc, washed with water, brine and dried. The solvent was removed under reduced pressure to give 3-methoxy-4-propargyloxybenzaldehyde (302 g, 97%) as yellow crystalline solid; mp 95° C.; δH (400 MHz, CDCl3) 2.56 (t, J=2.5 Hz, 1H, C≡CH), 3.95 (s, 3H, OCH3), 4.86 (d, J=2.5 Hz, 2H, OCH2); 7.14 (d, J5,6=6.8 Hz, 1H, H5), 7.44 (d, J2,6=1.4 Hz, 1H, H2), 7.47 (dd, J5,6=6.8, J2,6=1.4 Hz, 1H, H6), 9.87 (s, 1H, CHO); δC (100 MHz, CDCl3) 56.0, 56.6, 77.2, 77.4, 109.4, 112.5, 126.3, 130.9, 150.0, 152.1, 190.9; HRMS (ESI) Calculated for C11H10O3 [M+H]+, 191.0703 found 191.0706; νmax 1006, 1130, 1259, 1586, 1677, 2119, 2845, 2932, 3266 cm−1.