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DFT Studies on Metal-Controlled Regioselective Amination of N‑Acylpyrazoles with Azodicarboxylates
journal contribution
posted on 2019-09-13, 12:33 authored by Shujuan Lin, Zhenyang LinDensity
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.