A convenient, high-yielding procedure has been developed for the kilogram-scale synthesis of (±)-cis-3-acetoxy-4-phenylazetidin-2-one (3), a β-lactam that has been used in the semi-synthesis of Taxol®. The Staudinger reaction between hydrobenzamide (5) and acetoxyacetyl chloride in the presence of a base provided the α-benzylideneiminotoluene protected β-lactam 8. Without isolation of the intermediate β-lactam, the protecting group was removed under various reductive or hydrolytic conditions. The overall yields were about 80%. The synthesis of other (±)-cis-4-aryl- and 4-heteroarylazetidin-2-ones by this methodology has also been accomplished. These compounds are of value for the synthesis of 3′-Taxol® side-chain analogs and their preparation demonstrates the generality of this approach.
已经开发出一种方便、高产的程序,用于制备公斤级的(±)-顺式-3-乙酰氧基-4-苯基氮杂环戊二酮(3),这是一种β-内酰胺,已被用于紫杉醇®的半合成。在碱的存在下,羟基苯甲酰胺(5)和乙酰氧乙酰氯之间的Staudinger反应提供了α-苄基亚胺基甲苯保护的β-内酰胺8。在不分离中间体β-内酰胺的情况下,采用各种还原或水解条件去除保护基。总收率约为80%。通过这种方法还成功合成了其他(±)-顺式-4-芳基和4-杂环芳基氮杂环戊二酮。这些化合物对于合成3'-紫杉醇侧链类似物有价值,它们的制备展示了这种方法的普适性。