Process for preparing phencynonate optical isomer
An optical isomer, optical technology, used in organic chemistry and other directions
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Embodiment 1
[0024] Embodiment 1, the preparation of (2R, 5S)-2-tert-butyl-5-phenyl-1,3-dioxan-4-one (IIa)
[0025] Dissolve 20 g (0.13 mol) of R-mandelic acid in 200 mL of n-pentane, add 21.2 mL of pivalaldehyde (content 80%, 0.16 mol, purchased from Fluka Company), then add 0.5 mL of trifluoromethanesulfonic acid, install The water tank was refluxed for 6 hours, and the water was removed by the water separator. Cool to room temperature, add 100 mL of 8% sodium bicarbonate solution, distill off n-pentane under reduced pressure, and filter to obtain (2R,5S)-2-tert-butyl-5-phenyl-1,3-dioxane-4- Ketone (IIa), yield 27.1g, melting point 100-102°C, yield 95%, elemental analysis, theoretical value %: C 70.89, H 7.32; experimental value %: C 70.81, H 7.39. 1 H-NMR: δ (ppm, CDCl 3 ), 1.10 (s, 9H), 5.25 (s, 1H), 5.38 (s, 1H), 7.47 (m, 5H).
Embodiment 2
[0026] Embodiment 2, the preparation of (2S, 5R)-2-tert-butyl-5-phenyl-1,3-dioxan-4-one (IIb)
[0027] With reference to the method of Example 1, using (S)-mandelic acid as raw material, synthesize (2R, 5R)-2-tert-butyl-5-phenyl-1,3-dioxan-4-ketone (IIb) , melting point 100-102°C, yield 97%, elemental analysis, theoretical value %: C 70.89, H 7.32; experimental value %: C 70.83H 7.30. 1 H-NMR: δ (ppm, CDCl 3 ), 1.12 (s, 9H), 5.23 (s, 1H), 5.36 (s, 1H), 7.49 (m, 5H).
Embodiment 3
[0028] Example 3, Preparation of (2R, 5R)-2-tert-butyl-5-phenyl-5-(cyclopentyl-1-hydroxyl)-1,3-dioxan-4-one (IIIa)
[0029] Dissolve 10 g (45 mmol) of (2R,5S)-2-tert-butyl-5-phenyl-1,3-dioxan-4-one in 70 mL of dry tetrahydrofuran, cool to -78°C, add 60 mL of di( Lithium trimethylsilyl)amide (solution in tetrahydrofuran, 1.0M). 65 mmol of cyclopentanone was added dropwise under stirring, and the reaction was stirred for 2 hours, and 15 mL of saturated sodium hydrogen phosphate solution and 200 mL of saturated ammonium chloride solution were added dropwise. The organic layer was separated, the aqueous layer was extracted with ethyl acetate, the organic layers were combined, dried, and the solvent was evaporated to obtain (2R, 5R)-2-tert-butyl-5-phenyl-5-(cyclopentyl-1- Hydroxy)-1,3-dioxan-4-one (IIIa), yield 10.5 g, yield 74%. 1 H-NMR: δ (ppm, CDCl 3 ), 0.88 (s, 9H), 1.52-2.06 (m, 8H), 5.52 (s, 1H), 7.31 (m, 3H), 7.78 (dd, J=1.5, 8.3Hz, 2H).
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