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以(E)-2-己烯醛为起始原料,通过还原、Sharpless不对称环氧化、区域选择性还原、SN2亲核取代等反应制备光学活性的3-甲硫基己醇和3-甲硫基己基乙酸酯。首先(E)-2-己烯醛通过NaBH4还原得到(E)-2-己烯醇,产率91%。(E)-2-己烯醇通过Sharpless不对称环氧化,得到光学活性的2,3-环氧己醇,化学产率86%,产物ee值94%。2,3-环氧己醇用Red-Al进行区域选择性还原得到光学活性的1,3-己二醇,产率82%。将1,3-己二醇的伯羟基选择性转化为乙酸酯,3位羟基转化为甲磺酸酯,然后与自制的甲硫醇钾反应,经过SN2亲核取代反应后得到3-甲硫基己醇,三步反应总产率59%。3-甲硫基己醇用乙酸酐酯化得到3-甲硫基己基乙酸酯,产率87%。最终产物3-甲硫基己醇和3-甲硫基己基乙酸酯ee值均在94.0%左右。
Starting from (E) -2-hexenal, optically active 3-methylthioglycol and 3-methyl-3-methylthiohexanol were prepared by reduction, Sharpless asymmetric epoxidation, regioselective reduction and SN2 nucleophilic substitution Thiohexyl acetate. First (E) -2-hexenal was reduced by NaBH4 to give (E) -2-hexenol in 91% yield. (E) -2-Hexenol was asymmetrically epoxidized by Sharpless to afford optically active 2,3-epoxypentanol, 86% chemical yield and 94% ee value. The regioselective reduction of 2,3-epoxyhexanol with Red-Al gave the optically active 1,3-hexanediol in 82% yield. The primary hydroxyl of 1,3-hexanediol is selectively converted to acetate, the hydroxyl group at position 3 is converted to mesylate, and then reacted with self-made potassium methanethiolate. After SN2 nucleophilic substitution reaction, 3- Thiohexanol, three-step reaction total yield of 59%. 3-Methylthiohexanol was esterified with acetic anhydride to give 3-methylthiohexyl acetate in 87% yield. The final product 3-methylthioglycol and 3-methylthiohexyl acetate ee values are around 94.0%.