College of Chemistry and Chemical Engineering, Shanxi Datong University, Datong, People's Republic of China.
Curr Org Synth. 2023;20(6):589-594. doi: 10.2174/1570179420666221006113032.
Two efficient, scalable routes to bis-1,2,4-oxadiazole have been developed by tandem Staudinger/aza-Wittig reaction from the same starting material diaziglyoxime, isocyanates and triphenylphosphonium in good yields.
Two convenient and efficient routes for synthesizing diamino derivatives of bis-1,2,4- oxadiazoles were described.
This study provides a simple protocol for the synthesis of bis-1,2,4-oxadiazoles.
The two procedures were based on a tandem Staudinger/aza-Wittig reaction from the same starting material of diaziglyoxime, isocyanates and triphenylphosphonium.
In synthesis method I, diaziglyoxime 1 was treated with various aromatic or aliphatic isocyanates to give diazioxalimides 2 a high yield. Diazioxalimides 2 reacted with Ph3P to produce the iminophosphoranes 4; the reaction was directly heated from room temperature to 115 ℃ to get the desired diamino derivatives of bis-1,2,4-oxadiazole 4 in 72-92% yields. In synthesis method II, the same target compounds 4 were synthesized in a one-pot reaction by Ph3P and aromatic or aliphatic isocyanates in toluene for 10 h under 115 ℃ in 53-71% yields.
The two procedures provide proficient methods of making nitrogen-containing heterocyclic rings. The structures of target compounds 4 were identified by IR, 1HNMR, 13CNMR and HRMS.
通过串联 Staudinger/aza-Wittig 反应，从同一起始原料二氮烯基甘氨酸酯、异氰酸酯和三苯基膦出发，开发了两种高效、可扩展的双-1,2,4-噁二唑合成路线，产率良好。
描述了两种合成双-1,2,4-噁二唑二氨基衍生物的方便、高效路线。
本研究提供了一种合成双-1,2,4-噁二唑的简单方法。
这两种方法都是基于同一起始原料二氮烯基甘氨酸酯、异氰酸酯和三苯基膦的串联 Staudinger/aza-Wittig 反应。
在合成方法 I 中，二氮烯基甘氨酸酯 1 与各种芳香族或脂肪族异氰酸酯反应生成二噁唑啉 2，产率高。二噁唑啉 2 与 Ph3P 反应生成亚磷酰胺 4；反应直接从室温加热至 115℃，以 72-92%的收率得到所需的双-1,2,4-噁二唑二氨基衍生物 4。在合成方法 II 中，在 115℃下，相同的目标化合物 4 在一锅反应中由 Ph3P 和芳香族或脂肪族异氰酸酯在甲苯中反应 10 小时制得，产率为 53-71%。
这两种方法提供了制备含氮杂环的有效方法。目标化合物 4 的结构通过 IR、1HNMR、13CNMR 和 HRMS 进行了鉴定。
