A simple and efficient synthesis of cyclopentadienones via palladium-catalyzed cyclocarbonylation of alkynes under atmosphericpressure of carbonmonoxide has been developed. The transformation was carried out under mild and ligand-free conditions, a wide range of substrates and exceptional functional group tolerance.
The ruthenium-catalyzed hydrocarbamoylative cyclization of 1,6-diynes with formamides afforded exocyclic-diene-type α,β,γ,δ-unsaturated amides with 100% stereoselectivity. A plausible mechanism involving ruthenium hydride species is proposed to explain the experimental results. Some control experiments, performed using DMF-d7 and/or D2O, corroborate the proposed mechanism.
Metal-Free Transfer Hydroiodination of C–C Multiple Bonds
作者:Weiqiang Chen、Johannes C. L. Walker、Martin Oestreich
DOI:10.1021/jacs.8b12318
日期:2019.1.16
The design and a gram-scalesynthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Brønsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove
描述了基于环己-1,4-二烯的气态碘化氢替代品的设计和克级合成。通过用中等强度的布朗斯台德酸引发,碘化氢从替代物转移到 CC 多重键上,例如炔烃和丙二烯,而没有游离碘化氢的参与。代用品碎片化为甲苯和乙烯,易挥发废物。这种氢碘化反应避免了对碘化氢或氢碘酸的不稳定处理。通过这种方式,可以以立体控制的方式访问范围广泛的以前未知或难以制备的乙烯基碘。
O-Dihaloarenes as aryne precursors for nickel-catalyzed [2 + 2 + 2] cycloaddition with alkynes and nitriles
作者:Jen-Chieh Hsieh、Chien-Hong Cheng
DOI:10.1039/b801870g
日期:——
o-Dihaloarenes acting as aryne precursors react with acetylenes and nitriles catalyzed by the NiBr(2)(dppe)/dppe/Zn system to give substituted naphthalene, phenanthridine or triphenylene derivatives depending on the reaction conditions in moderate to excellent yields with good tolerance of functional groups.