The key intermediate of a 20(S)-camptothecin 1 synthesis was obtained in a highly enantioselective fashion using an enzyme-catalyzed resolution. A commercially available protease was found to exhibit the highest enantioselectivity with moderate activity, and (S)-ethyl 2-acetoxy-2[6-(acetoxymethyl)-1, 1-(ethylenedioxy)-5-oxo-1, 2, 3, 5-tetrahydroindolizin-7-yl]butanoate 7c of 98% e.e. was obtained as the remaining substrate.
20(S)-
喜树碱1合成的中间体是通过酶催化拆分以高度对映选择性方式获得的。发现一种市售
蛋白酶具有最高的对映选择性,且活性适中,剩余底物为98%对映异构体的(S)-乙基2-乙酰氧基-2[6-(乙酰氧甲基)-1,1-(亚乙二氧基)-5-氧代-1,2,3,5-四氢
吲哚嗪-7-基]
丁酸酯7c。