Uses
Dihydro-?2H-?pyran-?3(4H)?-?one is a general chemical reagent used in the synthesis of pharmaceuticals such as the preparation of tetrahydropyran-2-yl chromans, a highly selective beta-site amyloid precursor protein cleaving enzyme 1 (BACE) inhibitor.
Synthesis
The general procedure for the synthesis of dihydro-2H-pyran-3(4H)-ones using 3-hydroxytetrahydropyran as starting material was as follows: 3-hydroxytetrahydropyran (300 g, 2.9 mol) was dissolved in dichloromethane (3,000 g), followed by the addition of sodium acetate (287 g, 3.5 mol) and TEMPO (6 g). Sodium dichloroisocyanurate (374 g, 1.7 mol) was added in batches at 25 °C and the reaction temperature was maintained at 25 °C for a continuous period of 2 hours. After completion of the reaction, filtration was carried out and the organic phase was dried with anhydrous sodium sulfate (200 g). After filtration again, it was concentrated under reduced pressure using a rotary evaporator and distilled to collect a fraction with an oil bath temperature of 120 °C and a top temperature of 90 °C of the distillate. The final product was obtained as a colorless oily liquid which was tested to be 99% pure and 83% yield.
References
[1] Heterocycles, 2011, vol. 82, # 2, p. 1267 - 1282
[2] Patent: CN107382928, 2017, A. Location in patent: Paragraph 0007-0008; 0010-0011; 0013-0014
[3] Liebigs Annalen der Chemie, 1983, # 11, p. 1950 - 1958
[4] Tetrahedron, 2003, vol. 59, # 9, p. 1453 - 1467
[5] Patent: CN104650049, 2018, B. Location in patent: Paragraph 0603; 0604
