Brønsted acid cocatalysts in photocatalytic radical addition of α-amino C-H bonds across Michael acceptors.
Brønsted acid cocatalysts in photocatalytic radical addition of α-amino C-H bonds across Michael acceptors.
复制标题
DOI：
10.1021/jo400428m
复制
发表时间：
2013-04-19
期刊：
影响因子：
--
通讯作者：
Yoon TP
中科院分区：
文献类型：
--
作者：
Ruiz Espelt L;Wiensch EM;Yoon TP
与可用于邻近胺的亚甲基的氧化和亲核官能化的各种策略形成鲜明对比的是，报道了相对较少的用亲电反应伙伴修饰该位置的方法。在研究光生α-氨基自由基与亲电试剂的反应过程中，我们发现，在布朗斯台德酸助催化剂的存在下，N-芳基四氢异喹啉的自由基光氧化还原官能化效率显著提高。优化的条件提供了高产率和有效的转化为自由基加成产物的一系列结构修饰的四氢异喹啉和烯酮使用方便的家用光源和市售的Ru（bpy）3Cl 2作为光催化剂。我们对这种意想不到的加和效应的起源的研究表明，碳-碳键形成步骤被TFA加速，并且是自由基加成反应中布朗斯特酸催化的一个罕见例子。此外，从这些研究中得出的一个重要结论是，发现产品形成是由自由基链过程，而不是由光催化剂周转。总之，这些研究结果具有重要的意义，为未来的设计和光催化自由基过程的机制评估。
In marked contrast to the variety of strategies available for oxidation and nucleophilic functionalization of methylene groups adjacent to amines, relatively few approaches for modification of this position with electrophilic reaction partners have been reported. In the course of an investigation of the reactions of photogenerated α-amino radicals with electrophiles, we made the surprising observation that the efficiency of radical photoredox functionalization of N-aryl tetrahydroisoquinolines is dramatically increased in the presence of a Brønsted acid co-catalyst. Optimized conditions provide high yields and efficient conversion to radical addition products for a range of structurally modified tetrahydroisoquinolines and enones using convenient household light sources and commercially available Ru(bpy)3Cl2 as a photocatalyst. Our investigations into the origins of this unexpected additive effect have demonstrated that the carbon–carbon bond-forming step is accelerated by TFA and is a rare example of Brønsted acid catalysis in radical addition reactions. Moreover, a significant conclusion arising from these studies is the finding that product formation is dominated by radical chain processes and not by photocatalyst turnover. Together, these findings have important implications for the future design and mechanistic evaluation of photocatalytic radical processses.
登录
查看更多内容
影响因子：
15
作者：
LEWIS, FD;HO, TI
通讯作者：
HO, TI
影响因子：
3.6
作者：
CHIBA, T;TAKATA, Y
通讯作者：
TAKATA, Y
DOI：
10.1055/s-0032-1316592
发表时间：
2012-08
期刊：
Synlett : accounts and rapid communications in synthetic organic chemistry
影响因子：
--
作者：
Maity S;Zheng N
通讯作者：
Zheng N
影响因子：
1.8
作者：
Hoffmann, Norbert;Bertrand, Samuel;Pesch, Jens
通讯作者：
Pesch, Jens
影响因子：
--
作者：
Luo, Rong;Chen, Ying;Sen, Ayusman
通讯作者：
Sen, Ayusman