Premium
Mechanistic Insights into Copper‐Catalyzed Michael Reactions
Author(s) -
Pérez Elisabet,
MorenoMañas Marcial,
Sebastián Rosa María,
Vallribera Adelina,
Jutand Anny
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900985
Subject(s) - chemistry , cyclopentanone , catalysis , reaction rate constant , ketone , cyclic voltammetry , methyl vinyl ketone , deprotonation , medicinal chemistry , copper , dissociation (chemistry) , michael reaction , organometallic chemistry , toluene , reaction mechanism , order of reaction , kinetics , polymer chemistry , organic chemistry , electrochemistry , electrode , ion , physics , quantum mechanics
Abstract The mechanism of the Michael reaction between 2‐(ethoxycarbonyl)cyclopentanone ( 2 ) and methyl vinyl ketone ( 3 ) catalyzed by the copper(II) salt [Cu(5‐ t Bu‐Sal) 2 ] ( 1 ) has been investigated in toluene. The kinetics of the reaction of the catalyst 1 with the oxo ester 2 has been investigated by UV/Vis spectroscopy. It has been established that [Cu(5‐ t Bu‐Sal) 2 ] ( 1 ) reacts with 2 in a first‐order reaction, which is retarded by 5‐ t Bu‐Sal‐H ( 6 ), formed in the reaction after the reversible dissociation of [Cu(5‐ t Bu‐Sal) 2 ] to [Cu(5‐ t Bu‐Sal)] + and 5‐ t Bu‐Sal – and the subsequent reversible deprotonation of 2 by 5‐ t Bu‐Sal – . The formation of the mixed complex [Cu(5‐ t Bu‐Sal)(enolate‐ 2 )] ( 5 ) is proposed and has been characterized by cyclic voltammetry. The rate constant for the overall reaction leading to [Cu(5‐ t Bu‐Sal)(enolate‐ 2 )] ( 5 ) has been determined. The reaction of the mixed complex 5 with methylvinyl ketone ( 3 ), investigated by cyclic voltammetry, is proposed as the rate‐determining step.