STEREOSELECTIVE MICHAEL ADDITION OF THE IMINES OF ALPHA-AMINO ESTERS IN THE PRESENCE OF LITHIUM BROMIDE 1,8-DIAZABICYCLO[5.4.0]UNDEC-7-ENE

In the presence of lithium bromide/1,8-diazabicyclo[5.4.0]undec-7-ene, methyl [(2,2-dimethylpropylidene)-amino] acetate and methyl 2-[(2,2-dimethylpropylidene)amino]propanoate undergo anti- and syn-selective Michael additions with E and Z isomers of a,β-unsaturated esters and ketones, respectively. The frontier-orbital- and chelation-controlled transition state is responsible for the observed high selectivity. Catalytic reaction effectively suppresses undesired epimerization at the 2-position. Hydrolytic cyclization of the resulting Michael adducts leads to 5-oxopyrrolidine-2-carboxylates and l-pyrroline-5-carboxylates. © 1990, American Chemical Society. All rights reserved.