Enantioselective synthesis of bio-relevant 3,5-diaryl pyrazolines

The straightforward asymmetric construction of bio-relevant Δ(2)-pyrazolines having either N-(thio)amide or N-acetyl functional groups and flanked by aryl substituents such as phenol at C3 and C5 has been achieved through an enantioselective phase transfer organocatalytic addition of N-Boc hydrazine to chalcones followed by a transprotection sequence allowing N-Boc transformation into N-CXNHR (X = S, O) or N-Ac functional groups. This approach was applied to a straightforward elaboration of chiral monoamine oxidase inhibitor derivatives.