cobalt-catalyzed hetero-biaryl couplingreaction between aryl chlorides and arylmagnesium halides with unprecedented selectivity has been developed. The protocol utilizes 1 mol% of cheap Co(acac)3 as pre-catalyst and effects clean reactions of deactivated chlorostyrenes with only 1.1 equiv. of the Grignard reagent under mild conditions (30 °C, 5–30 min). Highly chemoselective reactions were realized even in
Two‐Step Procedure for the Synthesis of 1,2,3,4‐Tetrahydro‐quinolines
作者:Michael Warsitz、Sven Doye
DOI:10.1002/ejoc.202001337
日期:2020.12.7
addition products with high regioselectivity. A combination of this reaction with a subsequent intramolecular Buchwald–Hartwig amination creates a new and simple two‐stepprocedure that gives direct access to pharmacologically important 1,2,3,4‐tetrahydroquinolines.
Olefin-Assisted Iron-Catalyzed Alkylation of Aryl Chlorides
作者:Samet Gülak、Tim N. Gieshoff、Axel Jacobi von Wangelin
DOI:10.1002/adsc.201300095
日期:2013.8.12
AbstractA selective and operationally simple iron‐catalyzed cross‐coupling of aryl chlorides with alkylmagnesium halides has been developed. The reaction tolerates various functional groups and exhibits high chemoselectivity even in the presence of aryl bromides. Mechanistic studies indicate the essential role of the olefin substituent for substrate activation. Competing polymerization and reduction are effectively suppressed.magnified image
Development of N-Heterocyclic Carbene–Copper Complexes for 1,3-Halogen Migration
作者:Steven C. Schmid、Ryan Van Hoveln、Jared W. Rigoli、Jennifer M. Schomaker
DOI:10.1021/acs.organomet.5b00629
日期:2015.8.24
A series of NHC-copper complexes was synthesized and their potential to catalyze 1,3-halogen migration explored. Increasing the steric bulk around the metal drastically improves the lifetime of NHC-CuH species and promotes 1,3-halogen migration of both 2-bromo- and 2-chlorostyrenes through transfer of an aryl halogen to a benzylic carbon with concomitant arene borylation. The NHC-based system displays a broad substrate scope with notable advantages over previously reported phosphine-based catalysts, including complete selectivity for migration versus competing benzylic borylation, increased steric tolerance, efficient aryl chloride migration, and facile formation and characterization of organocopper catalytic intermediates. Experimental evidence and DFT calculations support a mechanism proceeding through dearomatization of a benzyl copper species, followed by a 1,4-halogen shift and borylation of the resulting ArCu(I) intermediate.