反应详情

2,6-Dimethoxyphenol (70 g, 0.45 mol) dissolved in 150 ml ethanol was added dropwise to a mixture of formaldehyde (68.5 ml of a 37.5% aqueous solution, 0.91 mol) and dimethylamine (148 ml of a 40% aqueous solution, 1 mol) and the resulting mixture was refluxed for 4 h. Ethanol was evaporated, the residue was partitioned between water and dichloromethane, the organic phase was dried over MgSO4 and evaporated to yield 95 g (99%) of a white solid, mp=78-80° C. To a dioxane solution (600 ml) of the dimethyl(3,5-dimethoxy-4-hydroxybenzyl)amine thus obtained (95 g, 0.45 mol) was added methyl iodide (61 ml, 0.98 mol) and the resulting mixture was refluxed for 2 h. The solid formed was filtered and washed with dioxane to yield 156 g (99%) of the trimethyl(3,5-dimethoxy-4-hydroxybenzyl)ammonium iodide salt. This latter was suspended in 600 ml xylene, triethyl phosphite (110 ml, 0.66 mol) was added dropwise and the resulting mixture was refluxed for 16 h. The solid formed was filtered and the solvent and excess of phosphite were evaporated under vacuum to yield diethyl (3,5-dimethoxy-4-hydroxybenzyl)phosphonate as a viscous oil (130 g, 97%).

1. temperaturethe resulting mixture was refluxed for 2 h
2. customThe solid formed
3. filtrationwas filtered
4. washwashed with dioxane