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Copper‐Catalyzed Coupling of ( E )‐Bromostilbene with Phenols/Azole: ESI‐MS Detection of Intermediates by Using an Ionically‐Tagged Ligand
Author(s) -
Limberger Jones,
Leal Bárbara C.,
Back Davi F.,
Dupont Jairton,
Monteiro Adriano L.
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201100925
Subject(s) - chemistry , halide , yield (engineering) , copper , phenols , phenol , ligand (biochemistry) , catalysis , scavenger , coupling reaction , derivative (finance) , radical , pyrazole , photochemistry , medicinal chemistry , inorganic chemistry , organic chemistry , materials science , receptor , economics , financial economics , metallurgy , biochemistry
A system based on copper/1,10‐phenanthroline efficiently promotes the coupling between phenols or pyrazole with ( E )‐bromostilbene. ( E )‐1‐Aryloxy‐1,2‐diphenylethenes were obtained from the coupling with phenols in good to excellent yields (69–90%). The exception was the reaction involving a phenol containing an electron‐withdrawing cyano group that required a longer reaction time and gave only 49% yield. Kinetic studies indicated the participation of the vinyl halide in the rate‐determining step. Under the conditions employed, the activation of the vinyl halide via a radical pathway was discarded using a radical scavenger test. By using an ionically‐tagged 1,10‐phenanthroline derivative as the ligand, various copper‐based ions were detected through ESI(+)‐MS. These ions suggested that formation of the active species [phenCuOAr(HOAr) 2 ] precedes the vinyl halide activation.