pyridine. With readily available chloroisoxazoles and a nucleophile, 2-picoline can be used as an inexpensive base. When a high yield of the acylation product is important, the reagent 2-(trimethylsilyl)pyridine/ethyl chloroformate is more suitable for the acylation with 2H-azirine-2-carbonyl chlorides.
2H-azirine-2-
羧酸的酰胺、酸酐、酯和
硫酯在室温下通过快速程序制备,包括 FeCl2 催化的 5-chloroisoxazoles 异构化为 2H-azirine-2-carbonyl chlorides,然后与 N 反应-、O-或 S-亲核试剂由邻位取代的
吡啶介导。使用现成的
氯异恶唑和亲核试剂,2-
甲基吡啶可用作廉价的碱。当酰化产物的高产率很重要时,试剂 2-(trimethylsilyl)pyridine/ethyl chloroformate 更适合与 2H-azirine-2-carbonyl chlorides 进行酰化。