Epichlorohydrin → 3-(Chloromethyl)hexahydro-1H-[1,4]oxazino[3,4-c][1,4]oxazine

Temperatur

170 °C

A solution of (3R)-morpholin-3-ylmethanol (4.21 g, 36.0 mmol) in 2-(chloromethyl)oxirane (28.2 mL, 0.360 mol) was heated to 40° C. for 3 h and then the solution was concentrated in vacuo. The intermediate was cooled in an ice bath and treated with 30.0 mL of concentrated sulfuric acid. The mixture was heated to 170° C. for 2 h and then allowed to cool to room temperature. The mixture was poured into ice-water and solid sodium bicarbonate was carefully added until the solution was basic. 10% methanol in ethyl acetate was added and the biphasic mixture was filtered. The layers were separated and the aqueous layer was extracted (3×100 mL 10% methanol in ethyl acetate). The combined organic layers were dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. Column chromatography (SiO2, 2:5 hexanes:ethyl acetate) provided 3-(chloromethyl)hexahydro-1H-[1,4]oxazino[3,4-c][1,4]oxazine 2.44 g (35%) as two separated diastereomers. (3R,9aS)-3-(chloromethyl)hexahydro-1H-[1,4]oxazino[3,4-c][1,4]oxazine: (0.886 g, 13% yield): 1H NMR (400 MHz, CDCl3): 3.91 (m, 3H), 3.82 (m, 1H), 3.68 (dt, 1H), 3.61 (dd, 1H), 3.47 (dd, 1H), 3.35 (t, 1H), 3.19 (t, 1H), 2.80 (d, 1H), 2.54 (m, 2H), 2.40 (m, 2H); MS (EI) for C8H14NO2Cl: 192 (MH+). (3S,9aS)-3-(chloromethyl)hexahydro-1H-[1,4]oxazino[3,4-c][1,4]oxazine: (1.55 g, 22% yield): 1H NMR (400 MHz, CDCl3): 3.85 (m, 2H), 3.73 (m, 3H), 3.50 (m, 2H), 3.29 (t, 1H), 3.18 (t, 1H), 2.85 (dd, 1H), 2.64 (dd, 1H), 2.40 (m, 2H), 2.17 (t, 1H); MS (EI) for C8H14NO2Cl: 192 (MH+).