DBU-catalyzed Michael addition of bulky glycine imine to α,β-unsaturated isoxazoles and pyrazolamides

Abstract

A DBU-catalyzed Michael additions of several pronucleophiles with high pK a values including bulky glycine imines, α-tetra-lone, 1-methyl-2-indolone and nitroalkanes to α,β-unsaturated isoxazoles and pyrazolamides have been realized in THF with 1.0 eq. LiBr as a additive at room temperature within 3 h to provide Michael adducts in excellent yields (up to 97%) and diastereoselectivities (> 20:1).