Carbohydrate-based enantiospecific syntheses of (R)-proline 1 and (S)-proline 2 from the previously reported D-erythro-hexonate ester 9 are described. Azide-substitution reactions on appropriately activated intermediates derived from ester 9, followed by reductive cyclization (H2/Pd–C), gave the substituted pyrrolidines 14 and 22, which were converted into their corresponding N-Cbz derivatives 16 and 24 in conventional manner. Mild acidic hydrolysis of these, followed by oxidation (sodium metaperiodate), gave the protected prolinals 3 and 4, which on further oxidation (sodium chlorite), followed by catalytic hydrogenolysis, gave the prolines 1 and 2. The N-Cbz-prolinol derivatives 5 and 6 are also reported.
描述了从之前报道的 D-赤式
己酸酯 9 中基于
碳水化合物的对映特异性合成 (R)-脯
氨酸 1 和 (S)-脯
氨酸 2。对衍生自酯 9 的适当活化的中间体进行
叠氮取代反应,然后进行还原环化 (H2/Pd-C),得到取代的
吡咯烷 14 和 22,它们以常规方式转化为相应的 N-Cbz 衍
生物 16 和 24。将这些物质进行轻度酸性
水解,然后氧化(偏
高碘酸钠),得到受保护的脯
氨酸 3 和 4,进一步氧化(
亚氯酸钠),然后催化氢解,得到脯
氨酸 1 和 2。 N-Cbz-脯
氨醇衍
生物还报道了图5和图6。