structurally designed toward the thermal C2–C6/[2 + 2] cyclisation mode, were prepared and characterised, one of them even by X-ray crystallography. The mechanism of their transformation to formal [2 + 2] cycloadducts was interrogated by trapping experiments and DFT computations. The results support a stepwise mechanism that involves the reversible formation of the C2–C6 diradical intermediate.
Gold-Catalyzed Cascade Cyclizations of 1,6-Diynyl Carbonates to Benzo[b]fluorenes Involving Arylation of Oxocarbenium Ion Intermediates and Decarboxylative Etherification
作者:Yifeng Chen、Ming Chen、Yuanhong Liu
DOI:10.1002/anie.201201799
日期:2012.6.25
cycloisomerizations give access to highly substituted benzo[b]fluorenes under mild reaction conditions (see scheme). Experimental results indicate that the in situ formed oxocarbeniumionintermediates, derived from gold‐catalyzed 3,3‐rearrangement and 6‐endo‐dig cyclization, undergo intramolecular arylation and subsequent decarboxylativeetherification to furnish the final ether products.
重排:在温和的反应条件下,所描述的金催化的环异构化反应可得到高度取代的苯并[ b ]芴(参见方案)。实验结果表明,在原位形成oxocarbenium离子中间体,衍生自金催化3,3-重排和6-内-挖环化,分子内经历芳基化和随后的脱羧醚化,得到最终的醚产物。
Gold-catalyzed cyclization of 1,6-diynyl dithioacetals via 1,7-carbene transfer and aromatic C–H functionalization
作者:Wei Xu、Ming Chen、Ning Sun、Yuanhong Liu
DOI:10.1039/c6cc05302e
日期:——
A gold-catalyzed cyclization of 1,6-diynyl dithioacetals has been developed, which provides an attractive route to diverse-substituted benzo[a]fluorene derivatives. The reaction is initiated through 1,2-sulfur migration of propargyl dithioacetal moiety to...