DFT Studies on Metal-Controlled Regioselective Amination of N‑Acylpyrazoles with Azodicarboxylates

2019-09-13T12:33:21Z (GMT) by Shujuan Lin Zhenyang Lin
Density functional theory calculations were carried out to study the reaction mechanisms of Ag­(I)- and Zn­(II)-catalyzed amination of unsaturated N-acylpyrazoles with azodicarboxylates. Our theoretical investigation focused on the origin of the metal-controlled regioselectivity (γ- versus α-amination). Through our calculations, it was found that the amination reactions occur via metal-dienolate intermediates, in which the Ag­(I) center prefers to coordinate with the α-carbon or the pyrazolyl N-donor site of the dienolate ligand, while the Zn­(II) center prefers to coordinate with the O-donor of the dienolate ligand. The different site preferences for coordination with dienolate between the Ag­(I) and Zn­(II) metal centers play the key roles in the different regioselectivity observed experimentally.