A range of 1,2,4-oxadiazoles, having a carbamoyl group at the 3-position, were synthesized from 2-methyl-4-nitroisoxazolin-5(2H)-one via three steps. Ammonolysis of this nitroisoxazolone afforded 2-amino-2-hydroxyimino-N-methylacetamide in excellent yield. O-Acylation of this key amidoxime, followed by ring closure, proceeded smoothly to give 3-carbamoyl-1,2,4-oxadiazoles having a substituent at the 5-position which could be easily modified by changing the O-acylating agent. Since each step requires only simple manipulations, the synthetic utility of this procedure is concluded to be high.
通过三个步骤,从2-甲基-
4-硝基异恶唑啉-5(2H)-酮合成了1,2,4-噁二唑系列,该系列在3位具有
氨基甲酰基。 硝基
异恶唑酮的
氨解反应以极高的产率生成2-
氨基-2-羟基亚
氨基-N-甲基乙酰胺。 该关键酰胺
肟的O-酰化反应,以及随后的环合反应,进展顺利,生成3-
氨基甲酰基-1,2,4-噁二唑,其5位具有取代基,可通过改变O-酰化剂轻松进行修饰。 由于每个步骤只需要简单的操作,因此该方法的合成实用性很高。