first example of near-room-temperature α-arylation of benzo[b]thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd2(dba)3·CHCl3 in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C–H activation at the α-C–H position, which becomes the
Room-Temperature Direct Arylation of Polyfluorinated Arenes under Biphasic Conditions
作者:Olivier René、Keith Fagnou
DOI:10.1021/ol1006136
日期:2010.5.7
New biphasic conditions for the palladium-catalyzed direct arylation of electron-poor fluorinated arenes have been developed. Taking advantage of biphasic chemistry, the use of an immiscible mixture of water and an organic solvent allows complete solubilization of all components of the system, enabling the reaction to proceed at room temperature in yields up to 99%.
Cyclization of Homopropargyl Chalcogenides by Copper(II) Salts: Selective Synthesis of 2,3-Dihydroselenophenes, 3-Arylselenophenes, and 3-Haloselenophenes/thiophenes
作者:Ricardo F. Schumacher、Alisson R. Rosário、Marlon R. Leite、Gilson Zeni
DOI:10.1002/chem.201302129
日期:2013.9.23
Copper(II) halide mediated cyclization of homopropargyl chalcogenides gave three types of chalcogenophene derivatives. Selective product formation was achieved by controlling solvent, temperature, and atmosphere. By using CuBr2 and 1,2‐dichloroethane at room temperature under ambient atmosphere, 4‐bromo dihydroselenophene derivatives were obtained, whereas CuBr2 and 1,2‐dichloroethane at reflux gave