The applicability of easily available ammonium salts to access aziridines via an ammonium ylide pathway was carefully investigated and compared with classical aza-Darzens approaches using α-bromo carbonyl nucleophiles. Whereas amide-stabilised ammonium ylides could be successfully reacted with aromatic aldimines to obtain the corresponding trans-aziridines in good yields and with high diastereoselectivities, α-bromo amides failed. In sharp contrast, acetophenone-based ylides did not give any aziridines while in this specific case α-bromo acetophenone derivatives gave the corresponding cis-aziridines in high yields and with excellent diastereoselectivities under optimised conditions.
我们仔细研究了易于获得的
铵盐通过醯化
铵途径获得
氮丙啶的适用性,并将其与使用δ-
溴羰基亲核体的经典氮杂-达臻方法进行了比较。酰胺稳定的醯化
铵可成功地与
芳香族醛亚胺反应,以良好的产率和高非对映选择性获得相应的反式
氮丙啶,而δ-
溴酰胺则失败了。与此形成鲜明对比的是,
苯乙酮基酰化物没有得到任何
氮丙啶,而在这种特定情况下,δ-
溴苯乙酮衍
生物在优化条件下以高产率和极好的非对映选择性得到了相应的顺式
氮丙啶。