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由吲哚出发,经4-三甲基硅吲哚的亲电取代反应,直接得4-乙氧羰甲硫基吲哚;再经C_5乙酰化,分子内环化,立体选择性氢化与水解等制得消旋创新霉素。消旋创新霉素与(一)-α-苯乙胺反应,得两个非对映体盐,分别以酸处理,得(—)和(+)-创新霉素;二者经差向异构化,得(+)和(—)-差向创新霉素,经光谱证实其绝对构型分别为3S,4S和3R,4R,分子中的甲基和羧基均以横键为优势构象。在四种立体异构体中,仅(—)-创新霉素有抗菌活性,其它异构体的酯经脱氢,还原、拆分等循环,可转化成具有抗菌活性的异构体。
Starting from indole, electrophilic substitution reaction of 4-trimethylsilylindole directly gives 4-ethoxycarbonyl methylthioindole; followed by C_5 acetylation, intramolecular cyclization, stereoselective hydrogenation and hydrolysis Such as racemic chloramphenicol. Racemic and neomycin with (a) -α-phenylethylamine reaction, two diastereomeric salts, were acid treatment, were (-) and (+) - Neomycin; The absolute configuration of (+) and (-) - epirubicin was confirmed by spectroscopy to be 3S, 4S and 3R, 4R, respectively. Of the four stereoisomers, only (-) - neomycin has an antibacterial activity. The esters of the other isomers can be converted to isomers with antibacterial activity by dehydrogenation, reduction, and resolution cycles.