Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes.
(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
Lebel
Hélène
H
Département de Chimie, Université de Montréal, PO Box 6128, Station Downtown, Montréal, Québec, Canada, H3C 3J7. helene.lebel@umontreal.ca
Davi
Michaël
M
Díez-Gonzalez
Silvia
S
Nolan
Steven P
SP