The present invention relates to improved process for the preparation of lamivudine or emtricitabine. Thus, (1′R,2′S,5′R)-menthyl-5(R,S)-acetoxy-[1,3]-oxathiolane-2(R)-carboxylate is reacted with N-propinoyl cytosine in hexamethyl disilazane and then added trityl perchlorate to obtain a solid containing (1′R,2′S,5′R)-menthyl-5S-(N-4″-propionylcytosin-1″-yl)-[1,3]-oxathiolane-2R-carboxylate. The solid obtained above is reacted with methane sulfonic acid to obtain (2R,5S)-5-(4-amino-2-oxo-2H-pyrimidin-1-yl)-[1,3]-oxathiolane-2-carboxylic acid, 2S-isopropyl-5R-methyl-1R-cyclohexyl ester. The above compound is reduced with sodium borohydride to obtain lamivudine.
本发明涉及一种改进的
拉米夫定或
恩替卡韦的制备方法。因此,将(1'R,2'S,5'R)-薄荷基-5(R,S)-乙酰氧基-[1,3]-
噁唑烷-2(R)-
羧酸酯与N-
丙烯酰
胞嘧啶在
六甲基二硅氮烷中反应,然后加入三
苯甲酰氯酸盐以得到固体,其中包含(1'R,2'S,5'R)-薄荷基-5S-(N-4″-丙酰基
胞嘧啶-1″-基)-[1,3]-
噁唑烷-2R-
羧酸酯。上述固体与
甲烷磺酸反应,得到(2R,5S)-5-(4-
氨基-2-氧代-2H-
嘧啶-1-基)-[1,3]-
噁唑烷-2-
羧酸,2S-异丙基-5R-甲基-1R-环己基酯。上述化合物用
硼氢化钠还原,得到
拉米夫定。