作者:Jesper Wengel、Jesper Lau、Erik B. Pedersen
DOI:10.1055/s-1989-27403
日期:——
(2E,4R)-4-Acetoxy-5-hydroxy-2-pentenal (3) was synthesized from L-arabinose (1) via 3,4-di-O-acetyl-L-arabinal (2). Phthalimide as its 1,8-diazabicyclo[5.4.0]undec-7-ene salt was coupled to 3 at C-3 to give an anomeric mixture of 2,3-dideoxy-3-phthalimido-L-erythro-pentofuranose, which was acetylated to give the corresponding di-O-acetyl derivative 4. Reaction of 4 with silylated 2,4-dihydroxypyrimidines 5 in the presence of trimethylsilyl triflate as catalyst afforded the nucleosides 6 and 7. The pure β-anomers obtained by fractional crystallization were deprotected with 33% methylamine in absolute ethanol to give the corresponding L-3′-aminonucleosides 8. After fractional crystallization of 6c the pure α-anomer 7c was obtained from the mother liquid and deprotected to give the corresponding L-3′-aminonucleoside 9c.
(2E,4R)-4-乙酰氧基-5-羟基-2-戊烯醛(3)由 L-阿拉伯糖(1)通过 3,4-二-O-乙酰基-L-阿拉伯醛(2)合成。 邻苯二甲酰亚胺作为其 1,8-二氮杂双环[5.4.0]十一-7-烯盐与 3 在 C-3 处偶联,得到 2,3-二脱氧-3-邻苯二甲酰亚胺-L-赤式戊呋喃糖的异构体混合物,将其乙酰化得到相应的二-O-乙酰基衍生物 4。4 与硅烷化的 2,4-二羟基嘧啶 5 在三甲基硅烷化物作为催化剂的存在下发生反应,得到核苷 6 和 7。通过分馏结晶得到的纯δ-异构体在绝对乙醇中用 33% 的甲胺进行脱保护,得到相应的 L-3′-amin 核苷 8。在对 6c 进行分馏结晶后,从母液中得到纯的δ-异构体 7c,并进行脱保护处理,得到相应的 L-3′- 氨基核苷 9c。