Coupling reactions of alpha-(N-carbamoyl)alkylcuprates with enol triflates derived from cyclic beta-keto esters: A facile approach to gamma-carbamoyl-alpha,beta-enoates.
alpha-(N-Carbamoylalkyl)cuprates couple with enol triflates derived from carbocyclic and heterocyclic (i.e., piperidinones) beta-keto esters. Product yields are higher with the alkyl(cyano)cuprates [i.e., RCu(CN)Li, 56-93%] than with the dialkylcuprate reagents (i.e., R(2)CuLi.LiCN). An enol nonaflate works as well as the corresponding enol triflate. A facile synthetic route to gamma-amino alpha,beta-enoates not readily prepared from gamma-keto-alpha,beta-enoates is thus established. The gamma-amino-alpha,beta-enoates, available via N-Boc deprotection, can be cyclized to annulated pyrrolin-2-ones.
Li
ShengJian
S
Howard L. Hunter Chemistry Laboratory, Clemson University, Clemson, South Carolina 29634-0973, USA.
Dieter
R Karl
RK