On the mechanism of the copper-catalyzed enantioselective 1,4-addition of grignard reagents to alpha,beta-unsaturated carbonyl compounds.
The mechanism of the enantioselective 1,4-addition of Grignard reagents to alpha,beta-unsaturated carbonyl compounds promoted by copper complexes of chiral ferrocenyl diphosphines is explored through kinetic, spectroscopic, and electrochemical analysis. On the basis of these studies, a structure of the active catalyst is proposed. The roles of the solvent, copper halide, and the Grignard reagent have been examined. Kinetic studies support a reductive elimination as the rate-limiting step in which the chiral catalyst, the substrate, and the Grignard reagent are involved. The thermodynamic activation parameters were determined from the temperature dependence of the reaction rate. The putative active species and the catalytic cycle of the reaction are discussed.
Harutyunyan
Syuzanna R
SR
Department of Organic Chemistry and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
López
Fernando
F
Browne
Wesley R
WR
Correa
Arkaitz
A
Peña
Diego
D
Badorrey
Ramon
R
Meetsma
Auke
A
Minnaard
Adriaan J
AJ
Feringa
Ben L
BL