Impact of solvent polarity on N-heterocyclic carbene-catalyzed beta-protonations of homoenolate equivalents.
N-Heterocyclic carbenes have been demonstrated to react through divergent pathways under the same conditions. Experimental and computational evidence demonstrates that the ability to favor generation of homoenolate equivalents from alpha,beta-unsaturated aldehydes versus the oxidation of aldehydes to esters is highly dependent upon the choice of solvent. The solvation environment plays an important role due to the mechanistic differences in these processes, with polar protic solvent favoring the oxidation process due to solvation of intermediates with greater charge separation.
Maki
Brooks E
BE
Department of Chemistry, Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, USA.
Patterson
Eric V
EV
Cramer
Christopher J
CJ
Scheidt
Karl A
KA
D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012997:Solvents / Q000737:chemistry
D006571:Heterocyclic Compounds; D012997:Solvents; C030011:carbene; D008697:Methane