Reaction Steps
N-((2S,3R,E)-1,3-dihydroxyoctadec-4-en-2-yl)cyclohexanecarboxamide (Compound I-1) was synthesized by adding 40 mg (0.29 mmol) of tert-butyl alcohol (HOBt) and 100 mg (0.29 mmol) of D-sphingosine/HCl at 0° C. to the solution of 38 mg (0.29 mmol) of cyclohexanecarboxylic acid in 25 mL of anhydrous tetrahydrofuran (THF). After 5 min, 67 mg (0.33 mmol) of dicyclohexylcarbodiimide (DCC) was added, and the pH of the solution was adjusted to 8 with 4-methylmorpholine. The reaction mixture was stirred at 0° C. for 2 h and at room temperature overnight. On evaporation the residue was dissolved in 100 mL of ethyl acetate. The solution was washed successively with saturated sodium bicarbonate, 5% potassium bisulfate, and saturated sodium chloride, and the organic phase was separated and dried over anhydrous magnesium sulfate for 2 h. After filtration and evaporation under reduced pressure, the crude product was recrystallized in ethyl ether to obtain 60 mg (51%) of N-((2S,3R,E)-1,3-dihydroxyoctadec-4-en-2-yl)cyclohexanecarboxamide as colorless powder. GC/MS (m/e): 391 [M+H2O]+. 1H NMR (d6-DMSO, 300 MHz) δ/ppm=7.224 (d, J=8.4 Hz, 1H), 5.513 (dt, J=15.3 Hz, J=6.6 Hz, 1H), 5.345 (dd, J=15.3 Hz, J=6.6 Hz, 1H), 4.789 (d, J=5.1 Hz, 1H), 4.422 (t, J=5.4 Hz, 1H), 3.872 (q, J=6.0 Hz, 1H), 3.636 (m, 1H), 3.446 (m, 2H), 2.088 (m, 1H), 1.917 (m, 2H), 1.652 (m, 6H), 1.225-1.157 (m, 26H), 0.843 (t, J=6.6 Hz, 3H). 13C NMR (d6-DMSO, 75 MHz) δ/ppm=132.083, 131.506, 72.063, 61.298, 55.665, 44.657, 32.358, 31.979, 30.172, 29.732, 29.656, 29.382, 29.246, 26.194, 26.042, 22.778, 14.624. Anal. Calcd for C25H47NO3: C, 73.30; H, 11.56; N, 3.42; O, 11.72. Found: C, 72.99; H, 11.64; N, 3.74; O, 11.91.
