Two new types of cyclic pyridinium ylides were designed and further used in reactions with azoalkenes to access structurally diverse spirocyclic compounds. A range of spiropyrazoline oxindoles could be smoothly obtained in up to 99% yield via a [4 + 1] annulation process with oxindole 3-pyridinium ylides as C1 synthons. Similarly, a series of spiropyrazoline indanones could be prepared with indanone
Synthesis of 1,4,5,6-tetrahydropyridazines and pyridazines <i>via</i> transition-metal-free (4 + 2) cycloaddition of alkoxyallenes with 1,2-diaza-1,3-dienes
作者:Qi Wu、Pan-Lin Shao、Yun He
DOI:10.1039/c9ra02712b
日期:——
We developed an economical and practical protocol for the synthesis of 1,4,5,6-tetrahydropyridazines. A diverse range of alkoxyallenes and 1,2-diaza-1,3-dienes undergo (4 + 2) cycloaddition to generate the desired products in excellent yields. The high efficiency, wide substrate scope and good functional group tolerance of this process, coupled with operational simplicity, render the method synthetically
An unprecedented [4+3] cycloaddition of in situ generated azoalkenes with C,N-cyclicazomethineimines has been developed without the use of any catalyst, providing an efficient and mild approach to synthesise highly functionalized 1,2,4,5-tetrazepine derivatives in high yields (76-92%).
Construction of 2,3,4,5-tetrahydro-1,2,4-triazines via [4 + 2] cycloaddition of α-halogeno hydrazones to imines
作者:Hong-Wu Zhao、Hai-Liang Pang、Yu-Di Zhao、Yue-Yang Liu、Li-Jiao Zhao、Xiao-Qin Chen、Xiu-Qing Song、Ning-Ning Feng、Juan Du
DOI:10.1039/c6ra27767e
日期:——
In the presence of sodium carbonate, the [4 + 2] cycloaddition of α-halogeno hydrazones to imines proceeded readily, and furnished 2,3,4,5-tetrahydro-1,2,4-triazines in moderate to high chemical yields.
Copper(I)-Catalyzed Asymmetric 1,3-Dipolar [3+4] Cycloaddition of Nitrones with Azoalkenes
作者:Liang Wei、Lu Yao、Zuo-Fei Wang、Hua Li、Hai-Yan Tao、Chun-Jiang Wang
DOI:10.1002/adsc.201600457
日期:2016.12.7
The first copper(I)‐catalyzed asymmetric1,3‐dipolar [3+4] cycloaddition of nitrones with azoalkenes has been developed, affording a variety of biologically important 1,2,4,5‐oxatriazepane derivatives in good yields with exclusive regioselectivities and excellent enantioselectivities.