Enantioselective conjugate addition of hydrazines to α,β-unsaturated imides.: Synthesis of chiral pyrazolidinones

This manuscript describes a highly enantioselective conjugate hydrazine addition to alpha,beta-unsaturated imides. The achiral template used has a significant impact on product enantioselectivity. Reactions at lower temperatures provide a protocol to add substituted hydrazines with selectivity resulting in the formation of a single pyrazolidinone product (> 98:2 selectivity). A variety of chiral pyrazolidinones with potential as chiral auxiliaries and ligands are accessible through the new conjugate addition methodology.