An unexpected elimination product leads to 4-alkyl-4-deoxy-4-<i>epi</i>-sialic acid derivatives
作者:Ivan Hemeon、Andrew J Bennet
DOI:10.1139/v08-006
日期:2008.3.1
subjected to the same conditions, enone 5 was a minor product (18%) while the major product did not eliminate HNO2 but instead cyclized to form a five-membered ring containing a hemiaminal linkage between C-2 and the amide nitrogen on C-5 (9, 70%). Conjugate addition to enone 5 opens up the potential to generate 4-substituted sialic acid derivatives, a general route to such compounds that has not been
一种有用的、意想不到的 β,γ-不饱和-α-酮酯((E)-5-acetamido-3,4,5-trideoxy-6,7:8,9-di-O-isopropylidene-D-manno-非 3-en-2-ulosonate 5) 在臭氧分解和色谱纯化其烯酸酯前体 5-acetamido-2,3,4,5-tetradeoxy-6,7:8,9- 后以 91% 的产率分离二-O-异亚丙基-2-亚甲基-4-硝基-D-甘油-D-半乳糖壬酸酯(6)。当 4R 烯酸酯(5-乙酰氨基-2,3,4,5-四脱氧-6,7:8,9-di-O-isopropylidene-2-methylene-4-nitro-D-glycero-D-talo -壬酸酯,7) 经受相同的条件,烯酮 5 是次要产物 (18%) 而主要产物没有消除 HNO2 而是环化形成一个五元环,在 C-2 和C-5 上的酰胺氮 (9, 70%)。与烯酮