DBU-catalyzed Michael additions of bulky glycine imine to β-arylfuryl substituted α,β-unsaturated esters

DBU-catalyzed Michael reactions between tert-butyl 2-((diphenylmethylene) amino)acetate and simple β-substituted α,β-unsaturated esters have been achieved in high yields (up to 95% yield) and diastereoselectivties (up to 99:1 dr) in the presence of 1.0 eq. of LiBr in acetonitrile under room temperature. The Michael adduct can be easily converted into trans-3-substituted pyroglutamic acid ester through in-situ acidic hydrolysis following lactamation.