A new catalytic method for the denitrogenative transannulation/cyclopropanation of in‐situ‐generated 2‐(diazomethyl)pyridines is described using a cobalt‐catalyzed radical‐activation mechanism. The method takes advantage of the inherent properties of a CoIII‐carbene radical intermediate and is the first report of denitrogenative transannulation/cyclopropanation by a radical‐activation mechanism, which
Copper-Catalyzed Ring Opening of [1.1.1]Propellane with Alkynes: Synthesis of Exocyclic Allenic Cyclobutanes
作者:Dániel Lasányi、Gergely L. Tolnai
DOI:10.1021/acs.orglett.9b03999
日期:2019.12.20
Despite the long history and interesting properties of propellanes, these compounds still have tremendous potential to be exploited in synthetic organic chemistry. Herein we disclose an experimentally simple procedure to achieve cyclobutane-containing allenes and alkynes through a copper-catalyzed ring opening of [1.1.1]propellane and subsequent reaction with ethynes.
The hydration of o-ethynylbenzoic acid derivatives, such as ethyl o-ethynylbenzoate, o-ethynylbenzonitrile, and o-ethynylbenzamide, in sulfuric acid in the presence of marcuric sulfate, afforded 3-substituted isocoumarins. The palladium-catalyzed reaction of o-halobenzoic acid derivatives with terminal acetylenes to obstain the starting materials for the cyclization is also described.
Pd/Cu-catalyzed one-pot reaction of 1-trimethylsilyl-2-arylalkynes with propargylic chlorides in the presence of TBAF is described. The present new procedure is applicable to a wide range of silylated arylalkynes with both electron-withdrawing and electron-donating substituents. Functionalized allenynes can thus be obtained in good yields without prior deprotection of the alkynes.
Fluoride-Catalyzed Cross-Coupling of Carbamoyl Fluorides and Alkynylsilanes
作者:Dusty Cadwallader、Dmytro Shevchuk、Tristan R. Tiburcio、Christine M. Le
DOI:10.1021/acs.orglett.3c02871
日期:2023.10.13
We report the synthesis of alkynamides via the cross-coupling of carbamoyl fluorides and alkynylsilanes catalyzed by tetrabutylammonium fluoride (TBAF). In contrast to previously reported transformations of carbamoyl fluorides, C–F bond cleavage is achieved under exceptionally mild conditions (room temperature, low catalyst loadings, and short reaction times) without the need for strongly nucleophilic