Abstract: 3-benzoylthio-2-methylpropionic acid racemate was synthesized by condensation and hydrolysis-esterification reaction of thioacetic acid with methacrylic acid，then (S)-3-benzoylthio- 2-methylpropionic acid was obtained by chemical resolution. The influencing factors in each step were taken into account. The results showed that 3-acetyl-mercapto-2-methyl-propionic acid（condensate A）was obtained with the yield of 95.6% when the molar ratio of thioacetic acid to methacrylic acid was 1.4∶1，reaction time was 2h and reaction temperature was 93 ℃. Condensate A was added into 11.8% sodium hydroxide aqueous solution to make it hydrolysis with kettle temperature below 20 ℃，then sodium salt was put into the kettle，and the same mole benzoyl chloride was dropped as condensate A into the kettle under low temperature. Two hours later，the product was obtained by acidifying the reaction mixture with hydrochloric acid，the yield of product in hydrolysis-esterification reaction was 96.7%. D-(+)-N-benzyl-α-phenylethylamine was used as the resolving agent to split the product，the yield in this step was 36%. Taking all the procedures above into consideration，the yield of final product was 33.3%. The product was characterized with MS，1H NMR and FT-IR analysis，and proved to be with high crystallinity by X ray diffraction.

Key words: (S)-3-benzoylthio-2-methylpropionic acid, thioacetic acid, methacrylic acid, synthesis, resolution

摘要： 以硫代乙酸、甲基丙烯酸为原料，经过缩合、水解-酯化得到3-苯甲酰巯基-2-甲基丙酸的消旋体，经化学拆分得到(S)-3-苯甲酰巯基-2-甲基丙酸。综合考察了缩合、水解-酯化、拆分过程中影响反应的因素，结果表明：硫代乙酸与甲基丙烯酸摩尔比为1.4︰1，反应时间为2 h、反应温度为93 ℃条件下，可以得到收率为95.6%的3-乙酰巯基-2-甲基丙酸（缩合物A）；控制釜温不超过20 ℃，将缩合物A加入11.8%的氢氧化钠水溶液中进行水解，水解完成后将下层钠盐投回釜内，然后在低温下滴加苯甲酰氯，反应进行2 h后将釜液调至酸性，产品逐渐析出，计算得水解-酯化总收率为96.7%；利用拆分剂D-(+)-N-苄基-α-苯乙胺对产品拆分，拆分收率为36.0%，综合以上三步总收率可达33.3%。其结构经核磁、质谱、红外分析确认且由X射线衍射分析结晶度非常高。

关键词: (S)-3-苯甲酰巯基-2-甲基丙酸, 硫代乙酸, 甲基丙烯酸, 合成, 拆分