反应详情

3-Hydroxy-pyran-4(1H)-one (5.6 g, 50 mmol, 1 eq.) was added to 50 ml water and the pH of the solution was adjusted to 10.5 using 50% aqueous sodium hydroxide. Acetaldehyde (2.64 g, 60 mmol, 1.25 eq.) dissolved in 20 ml water was slowly added dropwise over 1 hour and the solution allowed to stir overnight. The reaction mixture was acidified to pH 1 with 37% w/v hydrochloric acid and concentrated in vacuo to dryness. The residue was extracted with 2×70 ml of isopropanol at 90° C. The isopropanol extracts were combined and concentrated to yield after recrystallisation from toluene, the pure product (3.7 g, 47.4%) as a pale yellow crystalline solid. m.p. 131-132° C. [lit. 130—131° C. (Ichimoto, 1970)].

1. additionwas slowly added dropwise over 1 hour
2. concentrationconcentrated in vacuo to dryness
3. extractionThe residue was extracted with 2×70 ml of isopropanol at 90° C
4. concentrationconcentrated
5. customto yield
6. customafter recrystallisation from toluene
7. customm.p. 131-132° C. [lit. 130—131° C. (Ichimoto, 1970)]