A novel Rh(II)-catalyzed transannulation of 1-tosyl-1,2,3-triazoles with silyl or alkyl enolethers has been developed, which enables the facile synthesis of substituted pyrroles in a regiocontrollable manner. Moreover, the methodology could be extended to access 3-pyrrolin-2-one derivatives with silyl ketene acetals used as the reaction partner.
Revisiting the Influence of Silver in Cationic Gold Catalysis: A Practical Guide
作者:Zhichao Lu、Junbin Han、Gerald B. Hammond、Bo Xu
DOI:10.1021/acs.orglett.5b02224
日期:2015.9.18
salt to generate cationicgold from a gold catalyst precursor such as L–Au–Cl almost always has adverse effects on the reactivity of the cationicgold catalyst. A preformed L–Au+X– complex, generated by sonication followed by centrifugation, increases the reactivity in a gold catalyzed reaction. The adverse silver effect might be caused by the interaction of silver salts with gold intermediates.
过量的银盐会从金催化剂前体(例如L–Au–Cl)生成阳离子金,几乎总是对阳离子金催化剂的反应性产生不利影响。通过超声然后离心分离生成的预先形成的L–Au + X –络合物可提高金催化反应的反应性。银的不利影响可能是由银盐与金中间体的相互作用引起的。
Rhodium/Silver-Cocatalyzed Transannulation of <i>N</i>
-Sulfonyl-1,2,3-triazoles with Vinyl Azides: Divergent Synthesis of Pyrroles and 2 <i>H</i>
-Pyrazines
作者:Lin Zhang、Ge Sun、Xihe Bi
DOI:10.1002/asia.201601164
日期:2016.11.7
The first cyclization reaction between vinyl azides and N‐sulfonyl‐1,2,3‐triazoles is reported. A Rh/Ag binary metal catalyst system proved to be necessary for the successful cyclization. By varying the structure of vinyl azides, such reaction allows the divergent synthesis of pyrroles and 2H‐pyrazines. The cyclization reactions feature a broad substrate scope, good functional group tolerance, high
Synthesis of Pyrroles from Terminal Alkynes, <i>N</i>-Sulfonyl Azides, and Alkenyl Alkyl Ethers through 1-Sulfonyl-1,2,3-triazoles
作者:Cheol-Eui Kim、Sangjune Park、Dahan Eom、Boram Seo、Phil Ho Lee
DOI:10.1021/ol500718s
日期:2014.4.4
A method for synthesis of substituted pyrroles has been developed. 1-Sulfonyl-1,2,3-triazoles generated from terminal alkynes gave alpha-imino rhodium carbene complexes, which when reacted with alkenyl alkyl ethers afforded substituted pyrroles. The method can be efficiently applied to a one-pot sequential reaction starting from terminal alkynes.
Counterion Effects in a Gold-Catalyzed Synthesis of Pyrroles from Alkynyl Aziridines
作者:Paul W. Davies、Nicolas Martin
DOI:10.1021/ol900609f
日期:2009.6.4
Aryl-substituted N-tosyl alkynyl aziridines undergo a gold-catalyzed ring expansion to afford 2,5-substituted pyrrole products. Under certain conditions, a ring-expansion and rearrangement leads to 2,4-substituted pyrroles. The reaction pathway is determined by the counterion to the gold catalyst.