Preparation method of 2-ramification of methyl diol in optical purity
A technology of methyl alkyl glycol and derivatives, applied in the field of optically pure 2-methyl alkyl glycol derivatives
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Embodiment 1
[0108]
[0109] R 1 = H, R 2 = Me or R 1 = Me,R 2 =H, n=1 or 2, PG is a hydroxyl protecting group 2R-5-tert-butyldimethylsilyloxy-2-methyl-1-pentanol:
[0110] At room temperature, 11.4 grams of 4R-4-methyl-valerolactone as a raw material was dissolved in 100 ml of anhydrous tetrahydrofuran, and 8 grams of LiAlH 4 200ml of anhydrous tetrahydrofuran suspension, after the reaction is complete. The reaction was quenched with ethyl acetate, then water was added dropwise until the solid was white, and the white solid was removed by filtration, The residue was fully washed with tetrahydrofuran, the solvent was spun off under reduced pressure, and then distilled under reduced pressure to obtain 10.8 g of 2R-2-methyl-1,5-pentanediol (80°C / 0.1mmHg, 92%)
[0111] 1.2 g of 2R-2-methyl-1,5-pentanediol was dissolved in 10 ml of N, N-dimethylformamide, 1.5 equivalents of imidazole and 1.2 equivalents of TBDMSCl were added, stirred at room temperature for 10 hours, the product was e...
Embodiment 2
[0135]
[0136] R 1 = H, R 2 = Me or R 1 = Me,R 2 =H, n=0 or 1, PG is a hydroxyl protecting group 4R-5-methoxymethoxy-4-methyl-1-pentanol:
[0137] At room temperature, 11.4 g of the raw material 4R-4-methyl-valerolactone was dissolved in 100 ml of anhydrous methanol, 0.8 mL of concentrated sulfuric acid was added, and refluxed for 2 hours, after the reaction was completed. Extract with ether, saturated NaHCO 3 Solution washing, water washing, MgSO 4After drying, the solvent was spin-dried under reduced pressure at low temperature to obtain 14.4 g (99%) of 4R-4-methyl-5-hydroxy-valeric acid methyl ester. 1.4 g of 4R-4-methyl-5-hydroxy-pentanoic acid methyl ester was dissolved in 10 ml of dichloromethane, and 1.5 equivalents of DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) was added , 1.2 equivalents of chloromethoxymethane, stirred at room temperature for 5 hours, the product was extracted with dichloromethane, washed twice with water, MgSO 4 dry. Spin dry solvent. The ...
Embodiment 3
[0156]
[0157] R 1 = H, R 2 = Me or R 1 = Me,R 2 =H, n=1 or 2, Y=halogen
[0158] 4R-5-bromo-1-methoxymethoxy-4-methylpentane:
[0159] 19 g of 4R-5-methoxymethoxy-4-methyl-1-pentanol was dissolved in 100 mL of dichloromethane, and 1.5 equivalents of PPh were added 3 and 1.5 equivalents of CBr 4 , stirred at room temperature for 4 hours, the product was washed with saturated sodium bicarbonate solution, washed twice with water, MgSO 4 Dry and spin off the solvent. Distillation under reduced pressure at 40°C / 0.2 mmHg yielded 21.2 g of a colorless oil. Yield 95%.
[0160] C8H17BrO2: (225.12)
[0161] Elemental analysis: C%=42.13; H%=7.65; Mass spectrum: (M + , 224)
[0162] 1 H-NMR (CDCl 3 ): δ4.64(s, 2H), 3.4(m, 4H), 3.36(s, 3H), 1.59(m, 5H), 0.95(d, J=6Hz, 3H)
[0163] Made in a similar way:
[0164] 3R-4-bromo-1-methoxymethoxy-3-methylbutane: yield 94%, mass spectrum: (M + ,210);
[0165] 3R-4-bromo-1-ethoxymethoxy-3-methylbutane: yield 92%, mass spectrum...
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