作者:Hajime Nitta、Ikuo Ueda、Minoru Hatanaka
DOI:10.1039/a700650k
日期:——
The azido lactone 8 was prepared in a highly stereoselective manner
by introduction of an azide function to the lactone 6 derived from
L-aspartic acid, and then was converted into
(2S,3S)-3-amino-2-azido-4-hydroxybutanoic acid 4.
Four-component condensation of the amino acid 4, p-nitrobenzyl
isocyanide and formaldehyde or 2,2-diethoxyacetaldehyde furnished the
corresponding 3,4-cis-azetidinone 16 or 26 in excellent yield.
3-Methoxy-2-isooxacephalosporin was prepared by the intramolecular
acylation of imidazolide 23 derived from compound 16. 3-Unsubstituted
2-isocephem and 2-isooxacephem analogues were prepared from the
azetidinone 26.
叠氮内酯 8 是以高度立体选择性的方式制备的,方法是在 L-天冬氨酸衍生的内酯 6 中引入叠氮功能,然后将其转化为 (2S,3S)-3-氨基-2-叠氮-4-羟基丁酸 4。
将氨基酸 4、对硝基苄基异氰酸酯和甲醛或 2,2-二乙氧基乙醛进行四组份缩合,可得到相应的 3,4-顺式氮杂环丁酮 16 或 26,收率极高。从氮杂环丁酮 26 中制备出了 3-未取代的 2-异头孢和 2-异头孢类似物。