Synthesis of 3-(2-Pyridyl)-2-pyrazoline Derivatives as Candidates for Heterocyclic Chiral Ligands of the Chirality Relay Types

Abstract

The synthetic work of 3-(2-pyridyl)-2-pyrazolines bearing a chiral center at the 5-position is presented. Three synthetic routes have been examined, including (1) intramolecular cyclization of the hydrazones of α,β-unsaturated ketones, (2) synthesis of N-unsubstituted pyrazolines followed by the optical resolution of diastereomers of sulfonamide derivatives, and (3) asymmetric pyrazoline synthesis between enones and arylhydrazines catalyzed by a chiral metal acetate complex catalyst.