Natural (2R,3S,4S)-4-arnino-3-hydroxy-2-methyl-5-(3-pyridyl)pentanoic acid (1) present in antibiotic pyridomycin was synthesized. The 5,6-anhydro-1,2-O-isopropylidene-3-C-methyl-α-d-allofuranose (4) was prepared from (the known) 3-deoxy-1,2;5,6-di-O-isopropylidene-3-C-methyl-α-d-allofuranose (2). Regiospecific introduction of 3-pyridyl group to the C–6 of 4 was effected by 3-pyridyllithium. The product (5) was converted to the 5-azido derivative (7) by the SN2 substitution reaction of the 5-mesylate (6) of 5. Hydrolysis of 7 followed by two-stage oxidation with periodate-bromine in aqueous acetic acid afforded (2R,3S,4S)-4-azido-3-formyloxy-2-methyl-5-(3-pyridyl) pentanoic acid (9), which was transformed to the dihydrochloride of 1.
合成了抗生素
吡多霉素中的天然 (2R,3S,4S)-4-
氨基-3-羟基-2-甲基-5-(3-
吡啶基)
戊酸 (1)。5,6-anhydro-1,2-O-isopropylidene-3-C-methyl-α-d-allofuranose (4) 由(已知的)3-deoxy-1,2;5,6-di-O-isopropylidene-3-C-methyl-α-d-allofuranose (2) 制备而成。通过 3-
吡啶锂将 3-
吡啶基特异性地引入 4 的 C-6。通过 5 的 5-
甲磺酸酯 (6) 的 SN2 取代反应,产物 (5) 转化为 5-
叠氮衍
生物 (7)。
水解 7 后,在
乙酸水溶液中用高
碘酸盐-
溴进行两级氧化,得到 (2R,3S,4S)-4-
叠氮-3-甲酰氧基-2-甲基-5-(3-
吡啶基)
戊酸 (9),并将其转化为 1 的二盐酸盐。