The preparation of 3-azetidinones with different N-substituents and their transformation to 3-ethylideneazetidines has been studied in relation with a projected synthesis of 3-ethylideneazetidine-2-carboxylic acid (= polyoximic acid; 1). The stable crystalline 3-azetidinone hydrochloride (18), obtained by hydrogenolysis of the known 1-(diphenylmethyl)-3-azetidenone (4), is described for the first time, From this key intermediate, 3-oxoazetidine-derived amides, exemplified by benzamide 12,urethanes (e.g.17), and ureas (e.g.20) can be prepared in good yield (Scheme 3). The olefination of 3-azetidinones with alkylidene(triphenyl)phosphoranes is a perparatively useful process only for derivatives with a pyramidal N-atom, e.g. the diphenylmethyl derivative 4, and not for the amide 12 or the urethane 17 (Scheme 4). 3-Alkylidene-azetidines with an amide N-atom should, therefore, be prepared by exchange of the N-substituent after the introduction of the double bond.

中文翻译：

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3-氧代和3-乙炔氮杂环丁烷衍生物的制备^†

关于3-亚乙基氮杂环丁烷-2-羧酸（＝聚肟二酸；1）的预期合成，已经研究了具有不同N-取代基的3-氮杂环丁酮的制备及其向3-亚乙基氮杂环丁烷的转化。稳定的结晶3-氮杂环丁酮盐酸盐（18），通过已知的1-（二苯基甲基）的氢解得到-3- azetidenone（4），在第一次进行了说明，从该关键中间体，3-氧氮杂环丁烷衍生的酰胺，例示通过苯甲酰胺12，可以以高收率制备氨基甲酸酯（例如17）和尿素（例如20）（方案3）。3-氮杂环丁烷酮与亚烷基（三苯基）膦烷的烯烃化仅对具有金字塔形N原子的衍生物（例如二苯甲基衍生物4）有效，而对于酰胺12或氨基甲酸酯17而言则是可用于生产的方法（方案4）。因此，具有酰胺N原子的3-亚烷基-氮杂环丁烷应通过在引入双键后交换N-取代基来制备。