3-substituted-2-azetidinones has been prepared by the annelation of Schiff bases derived from cinnamaldehyde and D-threonine esters and their absolute configuration determined. When the β-hydroxyl group of threonine is unprotected, both enantiomeric forms of N-unsubstituted 3,4-disubstituted-2-azetidinones can be prepared from a single β-lactam-forming reaction. On the other hand, by converting the hydroxyl
通过使衍生自
肉桂醛和
D-苏氨酸酯的席夫
碱脱核,制备了各种旋光的3-取代的2-氮杂
环丁烷酮,并确定了它们的绝对构型。当苏
氨酸的β-羟基未被保护时,N-未取代的3,4-二取代-2-氮杂
环丁烷酮的两种对映体形式可以由单个β-内酰胺形成反应制备。另一方面,通过将
D-苏氨酸的羟基转化为大体积基团(例如,三苯基甲
硅烷基醚),可以诱导非常高的非对映选择性。这些β-内酰胺上的多个官能团可以轻松修饰,以产生适用于旋光糖,
生物碱以及单环和双环β-内酰胺抗生素的合成子。