众所周知,可见光驱动的光氧化还原催化是有机合成的强大工具。它的发生在很大程度上取决于光敏剂的两次放热单电子转移过程,而该过程受所涉及物质的氧化还原特性控制。因此,光敏剂固有的窄氧化还原电位范围不可避免地限制了它们的进一步可用性。最近发现敏化引发的电子转移可以有效克服这一重大挑战。然而,设计这种复杂催化系统的可行和实用策略相当稀缺。在此,我们报道了一个精心设计的双催化剂平台,其中双氰基吡嗪作为可见光增敏剂,并掺入吡嘘基的手性磷酸作为共增敏剂,我们证明了这种敏化引发的电子转移策略在不对称形式 de Mayo 型反应中的适用性。催化平台使热力学上不利的电子转移过程能够关闭氧化还原循环,并允许精确获得具有广泛底物范围的有价值的对映体富集 1,5-二酮。
A General Copper-Catalyzed Coupling of Azoles with Vinyl Bromides
作者:Qian Liao、Yuxing Wang、Liyun Zhang、Chanjuan Xi
DOI:10.1021/jo901105r
日期:2009.8.21
A copper-catalyzed methodology for the coupling of vinylbromides with azoles has been developed. This protocol uses a combination of 10 mol % of copper iodide and 20 mol % of ethylenediamine as catalyst. The reaction proceeds with various azoles and vinylbromides, and the double bond geometry of vinylbromides is retained under the reaction conditions.
Palladium-Catalyzed Stereocontrolled Vinylation of Azoles and Phenothiazine
作者:Artyom Y. Lebedev、Vyatcheslav V. Izmer、Denis N. Kazyul'kin、Irina P. Beletskaya、Alexander Z. Voskoboynikov
DOI:10.1021/ol0172370
日期:2002.2.1
with vinyl bromides catalyzed by palladium-phosphine complexes results in the respective N-vinylazoles in 30-99% yields. This reaction with cis- and trans-beta-bromostyrenes is stereospecific giving the respective products with full retention of configuration.
A protocol for the synthesis of terminal N-vinylazoles from aromatic aldehydes, DMSO, and azoles has been reported. In this strategy, DMSO was involved in the construction of the C=C bond as a terminal carbon synthon. Both aromatic aldehydes and azoles could be well tolerated and give the corresponding terminal N-vinylazoles in 52–91% yields. Based on preliminary experiments, a plausible mechanism
A new protocol for the synthesis of N-vinyl azoles using vinyl selenones and azoles in the presence of potassium hydroxide was developed. This reaction proceeded under mild and transition metal-free conditions through an addition/elimination cascade process. Both aromatic and aliphatic vinyl selenones and various mono-, bi- and tri-cyclic azoles can be tolerated and give terminal N-vinyl azoles in
Palladium-Catalyzed Oxidative Cross-Coupling of <i>N-</i>Tosylhydrazones with Indoles: Synthesis of <i>N-</i>Vinylindoles
作者:Xiaobao Zeng、Guolin Cheng、Jinhai Shen、Xiuling Cui
DOI:10.1021/ol401217h
日期:2013.6.21
A general and efficient palladium-catalyzed oxidative cross-coupling reaction of N-tosylhydrazones with indoles providing N-vinylindoles has been developed. The reaction proceeds smoothly with various indoles and N-tosylhydrazones in a stereocontrolled manner, and a wide variety of N-vinylindoles were obtained up to 99% yields for 26 examples.