反应详情

4-Hydroxybenzaldehyde (43.4 g, 0.355 mol), dihydropyran (44.4 ml, 0.495 mol), pyridinium p-toluenesulphonate (11.6 g, 0.046 mol, 0.1 mol equiv.) and dichloromethane (300 ml) were stirred for 16 h at room temperature. The mixture was washed with dilute aqueous sodium hydroxide solution (2×300 ml), water (200 ml), brine (300 ml), and finally with water (250 ml), dried over sodium sulphate and evaporated to dryness to leave a dark brown oil(63 g, 87%). This was used without further purification in the following step 1CW02. 1H NMR showed expected signals.

1. washThe mixture was washed with dilute aqueous sodium hydroxide solution (2×300 ml), water (200 ml), brine (300 ml)
2. dry with materialfinally with water (250 ml), dried over sodium sulphate
3. customevaporated to dryness