An I2-promoted, metal-free domino protocol for one-potsynthesis of 1,3,4-oxadiazoles has been developed via oxidative cleavage of C(sp2)–H or C(sp)–H bonds, followed by cyclization and deacylation. In this reaction, the use of K2CO3 as a base is found to be an essential factor in the cyclization and the C–C bond cleavage. This procedure proceeded smoothly in moderate to high yields with good functional
通过氧化裂解C(sp 2)–H或C(sp)–H键,然后环化,已开发出I 2促进的无金属多米诺协议,用于一锅合成1,3,4-恶二唑。和脱酰作用。在该反应中,发现使用K 2 CO 3作为碱是环化和C–C键断裂的必要因素。该过程以中等至高收率顺利进行,并具有良好的官能团相容性。
Direct Annulation of Hydrazides to 1,3,4-Oxadiazoles via Oxidative C(CO)–C(Methyl) Bond Cleavage of Methyl Ketones
strategy for the synthesis of 1,3,4-oxadiazoles was established through direct annulation of hydrazides with methylketones. It was found that the use of K2CO3 as a base achieves an unexpected and highly efficient C–C bondcleavage. This reaction is proposed to go through oxidativecleavage of Csp3–H bonds, followed by cyclization and deacylation.
通过将酰肼与甲基酮直接环合,建立了一种合成1,3,4-恶二唑的新策略。发现使用K 2 CO 3作为碱可以实现意想不到且高效的C–C键裂解。建议该反应通过C sp 3 -H键的氧化裂解,然后环化和脱酰基。
DMF as Methine Source: Copper‐Catalyzed Direct Annulation of Hydrazides to 1,3,4‐Oxadiazoles
作者:Shoucai Wang、Kai Wang、Xiangfei Kong、Shuhua Zhang、Guangbin Jiang、Fanghua Ji
DOI:10.1002/adsc.201900395
日期:2019.9.3
unprecedented Cu‐catalyzeddirectannulation of hydrazides with N,N‐dimethylformamide (DMF) was developed, providing an efficient synthesis of valuable 1,3,4‐oxadiazoles. This process features the short reaction time and can be safely conducted on gram scale. The reaction also facilitated the convenient synthesis of 1,3,4‐oxadiazole‐2(3H)‐ones. Moreover, the mechanistic studies suggest that the source of CH is