Sythesis of 1,3-dioxin-4-ones and their use in synthesis. XVIII. Synthesis of azetidin-2-ones from 1,3-dioxin-4-ones via 3-hydroxycarboxamides.
作者:Jun-ichi SAKAKI、Satoshi KOBAYASHI、Masayuki SATO、Chikasra KANEKO
DOI:10.1248/cpb.37.2952
日期:——
A general method for the synthesis of azetidin-2-ones from 1, 3-dioxin-4-ones is described. The method consists of 1) the formatin of β-ketocarboxamides, 2) their reduction to 3-hydroxycarboxamides, 3) mesylationg, and 4) base-mediated cyclization of 3-mesyloxycarboxamides to the final azetidinones. Stereochemical demand in the cyclizatino step has been clarified by using 5, 6-tri- and -tetramethylene derivatives of 2, 2-dimethyl-1, 3-dioxin-4-one. Microbiological reduction of the acetoacetamides by baker's yeast gave (S)-3-hydroxybutanamides of ≥98% optical purity, whose cyclization afforded (R)-4-methylazetidin-2-ones.
描述了一种从1,3-二氧戊环-4-酮合成氮杂环丁-2-酮的一般方法。该方法包括:1)形成β-酮羧酰胺,2)将其还原为3-羟基羧酰胺,3)甲磺酰化,以及4)3-甲磺酰氧基羧酰胺在碱介导下环化,得到最终的氮杂环丁酮。通过使用2,2-二甲基-1,3-二氧戊环-4-酮的5,6-三甲基和四甲基衍生物,阐明了环化步骤中的立体化学需求。利用面包酵母对乙酰乙酰胺进行微生物还原,得到了光学纯度≥98%的(S)-3-羟基丁酰胺,其环化产物为(R)-4-甲基氮杂环丁-2-酮。